MacLochlainns Weblog

Michael McLaughlin's Technical Blog

Site Admin

Archive for the ‘Java’ Category

Eclipse, Java, MySQL

without comments

While I previously blogged about installing Netbeans 8, some of my students would prefer to use the Eclipse IDE. This post shows how to install and configure Eclipse IDE, include the mysql-connector-java.jar, and write Java to access the MySQL.

You can download Eclipse IDE and then open it in Fedora’s Archive Manager. You can use the Archive Manager to Extract the Eclipse IDE to a directory of your choice. I opted to extract it into my student user’s home directory, which is /home/student.

After extracting the Eclipse IDE, you can check the contents of the eclipse directory with the following command:

ls -al eclipse

You should see the following:

drwxrwxr-x.  8 student student   4096 May  8 22:16 .
drwx------. 33 student student   4096 May  8 21:57 ..
-rw-rw-r--.  1 student student 119194 Mar 20 07:10 artifacts.xml
drwxrwxr-x. 11 student student   4096 May  8 22:16 configuration
drwxrwxr-x.  2 student student   4096 Mar 20 07:10 dropins
-rwxr-xr-x.  1 student student  78782 Mar 20 07:08 eclipse
-rw-rw-r--.  1 student student    315 Mar 20 07:10 eclipse.ini
-rw-rw-r--.  1 student student     60 Mar 17 15:11 .eclipseproduct
drwxrwxr-x. 41 student student   4096 Mar 20 07:10 features
-rwxr-xr-x.  1 student student 140566 Mar 20 07:08 icon.xpm
drwxrwxr-x.  4 student student   4096 Mar 20 07:09 p2
drwxrwxr-x. 12 student student  40960 Mar 20 07:10 plugins
drwxrwxr-x.  2 student student   4096 Mar 20 07:10 readme

You can launch the Eclipse IDE with the following command-line from the eclipse directory:

./eclipse &

While you can run this from the /home/student/eclipse directory, it’s best to create an alias for the Eclipse IDE in the student user’s .bashrc file:

# Set alias for Eclipse IDE tool.
alias eclipse="/home/student/eclipse/eclipse"

The next time you start the student user account, you can launch the Eclipse IDE by entering eclipse in the search box opened by clicking on the Activities menu.

The following steps take you through installing Eclipse on Fedora Linux, which is more or less the same as any Linux distribution. It’s very similar on Windows platforms too.

Eclipse Installation

EclipseInstall_01

  1. Navigate to eclipse.org/downloads web page to download the current version of the Eclipse software. Click the Linux 32 Bit or Linux 64 Bit link, as required for your operating system.

  1. Click the Green Arrow to download the Eclipse software.

  1. The next dialog gives you an option to open or save the software. Click the Open with radio button to open the archive file.

  1. This the Linux Archive Manager. Click the Extract button from the menu tab to open the archive file.

  1. This extract button on file chooser dialog to install Eclipse into the /home/student/eclipse directory. Click the Extract button to let the Archive Manager create a copy of those files.

  1. The Archive Manager presents a completion dialog. Click the Close button to close the Archive Manager.

After installing the Eclipse software, you can configure Eclipse. There are sixteen steps to setup the Eclipse product. You can launch the product with the

Eclipse Setup

You need to launch the Eclipse application to perform the following steps. The syntax is the following when you did create the alias mentioned earlier in the blog post:

eclipse &

The following steps cover setting up your workspace, project, and adding the MySQL JDBC Java archive.

  1. The branding dialog may display for 30 or more seconds before the Eclipse software application launches.

  1. The Workspace Launcher opens first on a new installation. You need to designate a starting folder. I’m using /home/student/workspace as my Workspace. Click the OK button when you enter a confirmed workspace.

  1. After setting the Workspace Launcher, you open to the Eclipse Welcome page. Click second of the two icons on the left to open a working Eclipse environment. Alternatively, you can connect to Tutorials on the same page.

  1. From the developer view, click on the File menu option, the New option on the list, and the Java Project option on the floating menu. Eclipse will now create a new Java project.

  1. The New Java Project dialog lets you enter a project name and it also gives you the ability to set some basic configuration details. As a rule, you simply enter the Project Name and accept the defaults before clicking the Finish button.

  1. After creating the new Java project, Eclipse returns you to the Welcome page. Click second of the two icons on the left to open a working Eclipse environment.

  1. Now you should see the working environment. Sometimes it takes the full screen but initially it doesn’t. Navigate to the lower right hand side, and expand the window to full size.

  1. Now you should see the full screen view of the Eclipse working environment.

  1. Now you create a new Java class by navigating to the File menu options, then the New menu option, and finally choosing the Class floating menu.

  1. The New Java Class dialog requires you to provide some information about the Java object you’re creating. The most important thing is the Java class name.

  1. The only difference in this copy of the New Java Class dialog is that I’ve entered HelloWorld as the Java Class’s name. Click the Finish button when you’re done.

  1. Eclipse should show you the following HelloWorld.java file. It’s missing a main() method. Add a static main() method to the HelloWorld.java class source file.

  1. This form shows the changes to the HelloWorld.java file. Specifically, it adds the It’s missing a main() method. Add a static main() method to the HelloWorld.java class source file.

  1. You can click the green arrow from the tool panel or you can click the Run menu option and Run submenu choice to test your program.

    1
    2
    3
    4
    
    // Class definition.
    public class HelloWorld {
      public static void main(String args[]) {
        System.out.println("Hello World."); }}

  1. The Save and Launch dialog tells you that you’re ready to test creating a copy of the Java class file. Click the OK button to continue.

  1. The results from your program are written to the Console portion of the Eclipse IDE. This concludes the setup of a workspace, project, and deployment of actual Java classes.

    Hello World.

Add MySQL JDBC Library

The following instructions add the MySQL Library and demonstrate how to write Java programs that connect to the MySQL database. They also use the mysql project.

EclipseMySQLLib_01

  1. Navigate to the Project menu and choose the Properties menu option.

EclipseMySQLLib_02

  1. The Properties menu option opens the Properties for the mysql project on the Order and Export tab. Click the Libraries tab to add an external library.

EclipseMySQLLib_03

  1. In the Libraries tab click the Add Library… button on the right to add an external library.

EclipseMySQLLib_04

  1. In the JAR Selection dialog, click on Computer in the Places list, then click on usr, click on share, and click on java. The Name list should now include mysql-connector-java.jar file, and you should click on it before clicking on the OK button.

EclipseMySQLLib_05

  1. You create new Java class file by clicking on the File menu. Then, you choose the New menu option and the Class menu option from the floating menu.

EclipseMySQLLib_06

  1. Enter MysqlConnector as the name of the new Java class file and click the Finish button to continue.

EclipseMySQLLib_07

  1. Eclipse generates the shell of the MysqlConnector class as shown in the illustration to the left.

EclipseMySQLLib_08

  1. You should replace the MysqlConnector class shell with the code below. Then, click the green arrow or the Run menu and Run menu option to compile and run the new MysqlConnector Java class file.

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.SQLException;
     
    public class MysqlConnector extends Object {
      public static void main(String[] args) {
        try {
          /* The newInstance() call is a work around for some
             broken Java implementations. */
          Class.forName("com.mysql.jdbc.Driver").newInstance();
     
          /* Verify the Java class path. */
          System.out.println("====================");
          System.out.println("CLASSPATH [" + System.getProperty("java.class.path") + "]");
          System.out.println("====================");
     
        } catch (Exception e) {}
        finally {
          /* Verify the Java class path. */
          System.out.println("====================");
          System.out.println("CLASSPATH [" + System.getProperty("java.class.path") + "]");
          System.out.println("====================");
        }
      }
    }

EclipseMySQLLib_09

  1. The Save and Launch dialog informs you are saving a MysqlConnector.java file to your mysql project. Click the OK button to continue.

EclipseMySQLLib_10

  1. The next screen shows that the program successfully connected to the MySQL database by printing the following information to the Console output tab.

    ====================
    CLASSPATH [/home/student/Code/workspace/MySQL/bin:/usr/share/java/mysql-connector-java.jar]
    ====================
    ====================
    CLASSPATH [/home/student/Code/workspace/MySQL/bin:/usr/share/java/mysql-connector-java.jar]
    ====================

EclipseMySQLLib_11

  1. Instead of repeating steps #5 through #10, the image displays the testing of the MysqlResults class file. The code follows below:

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    
    /* Import the java.sql.* package. */
    import java.sql.*;
     
    /* You can't include the following on Linux without raising an exception. */
    // import com.mysql.jdbc.Driver;
     
    public class MySQLResult {
      public MySQLResult() {
        /* Declare variables that require explicit assignments because
           they're addressed in the finally block. */
        Connection conn = null;
        Statement stmt = null;
        ResultSet rset = null;
     
        /* Declare other variables. */
        String url;
        String username = "student";
        String password = "student";
        String database = "studentdb";
        String hostname = "localhost";
        String port = "3306";
        String sql;
     
        /* Attempt a connection. */
        try {
          // Set URL.
          url = "jdbc:mysql://" + hostname + ":" + port + "/" + database;
     
          // Create instance of MySQL.
          Class.forName ("com.mysql.jdbc.Driver").newInstance();
          conn = DriverManager.getConnection (url, username, password);
     
          // Query the version of the database, relies on *_ri2.sql scripts.
          sql = "SELECT i.item_title, ra.rating FROM item i INNER JOIN rating_agency ra ON i.item_rating_id = ra.rating_agency_id";
          stmt = conn.createStatement();
          rset = stmt.executeQuery(sql);
     
          System.out.println ("Database connection established");
     
          // Read row returns for one column.
          while (rset.next()) {
            System.out.println(rset.getString(1) + ", " + rset.getString(2)); }
     
        }
        catch (SQLException e) {
          System.err.println ("Cannot connect to database server (SQLException):");
          System.out.println(e.getMessage());
        }
        catch (ClassNotFoundException e) {
          System.err.println ("Cannot connect to database server (ClassNotFoundException)");
          System.out.println(e.getMessage());
        }
        catch (InstantiationException e) {
          System.err.println ("Cannot connect to database server (InstantiationException)");
          System.out.println(e.getMessage());
        }
        catch (IllegalAccessException e) {
          System.err.println ("Cannot connect to database server (IllegalAccesException)");
          System.out.println(e.getMessage());
        }
        finally {
          if (conn != null) {
            try {
              rset.close();
              stmt.close();
              conn.close();
              System.out.println ("Database connection terminated");
            }
            catch (Exception e) { /* ignore close errors */ }
          }
        }
      }
      /* Unit test. */
      public static void main(String args[]) {
        new MySQLResult(); }
    }

    After you click the green arrow or the Run menu and Run menu option to compile and run the program, you should see the following output. That is if you’re using my create_mysql_store_ri2.sql and seed_mysql_store_ri2.sql files.

    Database connection established
    I Remember Mama, NR
    Tora! Tora! Tora!, G
    A Man for All Seasons, G
    Around the World in 80 Days, G
    Camelot, G
    Christmas Carol, G
    I Remember Mama, G
    The Hunt for Red October, PG
    Star Wars I, PG
    Star Wars II, PG
    Star Wars II, PG
    The Chronicles of Narnia, PG
    Beau Geste, PG
    Hook, PG
    Harry Potter and the Sorcerer's Stone, PG
    Scrooge, PG
    Harry Potter and the Sorcer's Stone, PG
    Harry Potter and the Sorcer's Stone, PG
    Harry Potter and the Chamber of Secrets, PG
    Harry Potter and the Chamber of Secrets, PG
    Harry Potter and the Prisoner of Azkaban, PG
    Harry Potter and the Prisoner of Azkaban, PG
    Harry Potter and the Half Blood Prince, PG
    Star Wars III, PG-13
    Casino Royale, PG-13
    Casino Royale, PG-13
    Die Another Day, PG-13
    Die Another Day, PG-13
    Die Another Day, PG-13
    Golden Eye, PG-13
    Golden Eye, PG-13
    Tomorrow Never Dies, PG-13
    Tomorrow Never Dies, PG-13
    The World Is Not Enough, PG-13
    Clear and Present Danger, PG-13
    Clear and Present Danger, PG-13
    Harry Potter and the Goblet of Fire, PG-13
    Harry Potter and the Goblet of Fire, PG-13
    Harry Potter and the Goblet of Fire, PG-13
    Harry Potter and the Order of the Phoenix, PG-13
    Harry Potter and the Deathly Hallows, Part 1, PG-13
    Harry Potter and the Deathly Hallows, Part 2, PG-13
    Brave Heart, R
    The Chronicles of Narnia, E
    MarioKart, E
    Need for Speed, E
    Cars, E
    RoboCop, M
    Pirates of the Caribbean, T
    Splinter Cell, T
    The DaVinci Code, T
    Database connection terminated

As always, I hope the note helps those trying to work with the Eclipse product.

Written by maclochlainn

May 10th, 2015 at 2:09 am

Netbeans 8 – Fedora

with 3 comments

Some of my students want to use the Fedora image that I built for my database classes in my Java software development life cycle course. As a result, they wanted a Java development environment installed. I examined JDeveloper 11g (11.1.1.7.0) and 12c (12.1.3) but resolved on the more generic Netbeans 8 (8.0.2) IDE.

JDK 7 with Netbeans 8 Download

You can download the generic Netbeans 8 IDE, the JDK 7 with Netbeans, or the JDK 8 with Netbeans for the Linux installation. After you download the executable program, you should follow these instructions to install the Netbeans 8 IDE on Fedora.

As the student user, you can download the file to your ~student/Downloads directory and then run these two commands:

chmod +x ./jdk-7u80-nb-8_0_2-linux-x64.sh
sudo ./jdk-7u80-nb-8_0_2-linux-x64.sh

It produces the following output log:

Configuring the installer...
Searching for JVM on the system...
Preparing bundled JVM ...
Extracting installation data...
Running the installer wizard...

Then, it launches the installer. These screens show you how to install and create your first Java project.

JDK 7 with Netbeans 8 Installation

JDK7Netbeans8_01

  1. The first installation dialog welcomes you to the JDK 7 Update and NetBeans 8 Installer. Click the Next button to proceed.

JDK7Netbeans8_02

  1. The second installation dialog asks you to accept the terms in the license agreement. Click the Next button to proceed.

JDK7Netbeans8_03

  1. The third installation dialog asks you to install Netbeans 8. Click the Browse button if you would like to install it in a different area. Click the Next button to proceed.

JDK7Netbeans8_04

  1. The fourth installation dialog asks you to install another Java JDK 7 that supports the current release of Netbeans 8. Click the Browse button if you would like to install it in a different area. Click the Next button to proceed.

JDK7Netbeans8_05

  1. The fifth installation dialog shows you the progress bar for installing Java JDK 7 that supports the current release of Netbeans 8. You may not need to click the Next button to proceed because it should progress to the Netbeans progress dialog. Click the Next button to proceed when it doesn’t do it automatically.

JDK7Netbeans8_06

  1. The sixth installation dialog shows you the progress bar for installing Netbeans 8. Click the Next button to proceed when it doesn’t do it automatically.

JDK7Netbeans8_08

  1. The next screen is the final screen of the Java SE Development Kit and NetBeans IDE Installer. Click the Finish button to complete the installation.

After the installation, you need to check if the netbeans program can be found by users. It shouldn’t be found at this point because it isn’t in the default $PATH environment variable.

Configuring the student user

You can set the $PATH variable dynamically like this:

export PATH=$PATH:/usr/local/netbeans-8.0.2/bin

The netbeans program location was set in Step #4 of the Netbeans installation. After setting the $PATH environment variable, you can run netbeans with this syntax:

./netbeans &

However, the better approach is to put the following lines in your .bashrc file. This change ensures that you can access the netbeans program anytime you launch a Terminal session.

# Add netbeans to the user's PATH variable.
export PATH=$PATH:/usr/local/netbeans-8.0.2/bin

After you have configured the student user’s .bashrc file, you can now use Netbeans to create a Java project.

Create a new Netbeans project

JDK7Netbeans8_07

  1. The next screen is the Netbeans 8 Start Page. This is where you can create your first Java development project.

JDK7Netbeans8_09

  1. You click the File menu and then the New Project menu option to open a new project.

JDK7Netbeans8_10

  1. It launches the New Project dialog at Step #1 – Choose Project, where you choose Java from your Categories list and Java Application from the Projects list. You click the Next button to continue.

JDK7Netbeans8_11

  1. It launches the New Project dialog at Step #2 – Name and Location, where you enter a Project Name. The example uses MySQLJava as the project name. You click the Next button to continue.

JDK7Netbeans8_12

  1. It launches the MySQLJava.java tab in the Netbeans 8 application. This is where you can enter your code.

After you successfully download the Java 7 SE and Netbeans 8, you should download JDK 8 with Netbeans 8 because Java 7 EOL (End-of-Life) is April 30th, 2015. You may think that you need to uninstall the JDK 7 with Netbeans 8 before you install the JDK 8 with Netbeans 8, but you don’t have to do so. When you install JDK 8 with Netbeans 8 into an environment with a preinstalled JDK 7 with Netbeans 8, the installer only adds the JDK 8.

The following segments of the post show you how to download and install JDK 8 with Netbeans 8, and how to configure Netbeans to work with the JDK 7 and JDK 8 as interchangeable libraries.

JDK 8 with Netbeans 8 Download

You can now download the JDK 8 with Netbeans for the Linux installation. After you download the executable program, you should follow these instructions to install it on Fedora.

As the student user, you can download the file to your ~student/Downloads directory and then run these two commands:

chmod +x ./jdk-8u45-nb-8_0_2-linux-x64.sh
sudo ./jdk-8u45-nb-8_0_2-linux-x64.sh

It produces the following output log:

Configuring the installer...
Searching for JVM on the system...
Preparing bundled JVM ...
Extracting installation data...
Running the installer wizard...

Then, it launches the installer, which will be very similar to the steps you went through earlier. There are differences. There are only five screens that you navigate as opposed to the seven from the earlier JDK 7 with Netbeans 8 installation, as you’ll see below.

JDK 8 with Netbeans 8 Installation

JDK8Netbeans_01

  1. The first installation dialog welcomes you to the JDK 8 Update and NetBeans 8 Installer. Click the Next button to proceed.

JDK8Netbeans_02

  1. The second installation dialog installs the JDK 8. Click the Next button to proceed.

JDK8Netbeans_03

  1. The third installation dialog is a summary of what you’ll install. Click the Install button to proceed.

JDK8Netbeans_04

  1. The fourth installation dialog shows you a progress bar. You don’t need to do anything but watch the progress.

JDK8Netbeans_05

  1. The fifth installation dialog shows you the installation is complete. Click the Finish button to proceed when it doesn’t do it automatically.

After you have installed the JDK 8 SE, you can use Netbeans to add the JDK 8 platform.

Add the JDK 8 Platform to Netbeans 8

JDK8Platform_01

  1. After you open Netbeans 8, you choose the Tools menu choice. Then, you select the Java Platforms menu option.

JDK8Platform_02

  1. It launches the Java Platform Manager dialog. You click the Add Platform button to add the JDK 8 platform.

JDK8Platform_03

  1. It launches the Add Java Platform dialog. Leave the Java Standard Edition radio button checked. You click the Next button to proceed.

JDK8Platform_04

  1. It launches the Add Java Platform file chooser dialog. Here you navigate to find the JDK 8 software, which is located in /usr/local/jdk1.8.0_45 directory.

JDK8Platform_05

  1. After selecting the /usr/local/jdk1.8.0_45 directory as the platform folder, click the Next button to proceed.

JDK8Platform_06

  1. After setting the directory, you’re asked to verify the Java Platform information. If it’s correct, click the Finish button to proceed.

JDK8Platform_07

  1. After finishing the installation, you’ll see that you have two installed Java Platforms. Unfortunately, the first one installed is the default unless you modify the netbeans.conf file. You click the Close button to complete the process.

Set JDK 8 Platform as the Default Java Platform for Netbeans 8

After adding the JDK 8 Java Platform, you can change the default setting my manually editing the /usr/local/netbeans-8.0.2/etc/netbeans.conf file. You simply remark out the line for JDK 7 and replace it with one for JDK 8, as shown below. The next time you boot the Netbeans application it uses Java 1.8.

# netbeans_jdkhome="/usr/local/jdk1.7.0_80"
netbeans_jdkhome="/usr/local/jdk1.8.0_45"

The next time you launch Netbeans 8, it will use JDK 8 because you set that as the default Java Platform

As always, I hope this helps those looking for information like this.

Written by maclochlainn

April 29th, 2015 at 1:32 am

Java-MySQL Program

with one comment

It turns out that configuring Perl wasn’t the last step for my student instance. It appears that I neglected to configure my student instance to support Java connectivity to MySQL. This post reviews the configuration of Java to run programs against MySQL. It also covers the new syntax on how you register a DriverManager, and avoid Java compilation errors with the older syntax.

In prior posts, I’ve shown how to use Perl , PHP, Python, and Ruby languages to query a MySQL database on Linux.

You need to install the Open JDK libraries with the yum utility command:

yum install -y java-1.7.0-openjdk*

It should generate the following log output:

Loaded plugins: langpacks, refresh-packagekit
Package 1:java-1.7.0-openjdk-1.7.0.75-2.5.4.2.fc20.x86_64 already installed and latest version
Package 1:java-1.7.0-openjdk-headless-1.7.0.75-2.5.4.2.fc20.x86_64 already installed and latest version
Resolving Dependencies
--> Running transaction check
---> Package java-1.7.0-openjdk-accessibility.x86_64 1:1.7.0.75-2.5.4.2.fc20 will be installed
--> Processing Dependency: java-atk-wrapper for package: 1:java-1.7.0-openjdk-accessibility-1.7.0.75-2.5.4.2.fc20.x86_64
---> Package java-1.7.0-openjdk-demo.x86_64 1:1.7.0.75-2.5.4.2.fc20 will be installed
---> Package java-1.7.0-openjdk-devel.x86_64 1:1.7.0.75-2.5.4.2.fc20 will be installed
---> Package java-1.7.0-openjdk-javadoc.noarch 1:1.7.0.75-2.5.4.2.fc20 will be installed
---> Package java-1.7.0-openjdk-src.x86_64 1:1.7.0.75-2.5.4.2.fc20 will be installed
--> Running transaction check
---> Package java-atk-wrapper.x86_64 0:0.30.4-4.fc20 will be installed
--> Finished Dependency Resolution
 
Dependencies Resolved
 
================================================================================
 Package                          Arch   Version                  Repository
                                                                           Size
================================================================================
Installing:
 java-1.7.0-openjdk-accessibility x86_64 1:1.7.0.75-2.5.4.2.fc20  updates  32 k
 java-1.7.0-openjdk-demo          x86_64 1:1.7.0.75-2.5.4.2.fc20  updates 1.9 M
 java-1.7.0-openjdk-devel         x86_64 1:1.7.0.75-2.5.4.2.fc20  updates 9.2 M
 java-1.7.0-openjdk-javadoc       noarch 1:1.7.0.75-2.5.4.2.fc20  updates  14 M
 java-1.7.0-openjdk-src           x86_64 1:1.7.0.75-2.5.4.2.fc20  updates  39 M
Installing for dependencies:
 java-atk-wrapper                 x86_64 0.30.4-4.fc20            fedora   71 k
 
Transaction Summary
================================================================================
Install  12 Packages (+1 Dependent package)
 
Total download size: 163 M
Installed size: 765 M
Downloading packages:
(1/6): java-1.7.0-openjdk-accessibility-1.7.0.75-2.5.4.2.f |  32 kB  00:00     
(2/6): java-1.7.0-openjdk-demo-1.7.0.75-2.5.4.2.fc20.x86_6 | 1.9 MB  00:02     
(3/6): java-1.7.0-openjdk-devel-1.7.0.75-2.5.4.2.fc20.x86_ | 9.2 MB  00:05     
(4/6): java-1.7.0-openjdk-javadoc-1.7.0.75-2.5.4.2.fc20.no |  14 MB  00:04     
(5/6): java-atk-wrapper-0.30.4-4.fc20.x86_64.rpm           |  71 kB  00:00     
(6/6): java-1.7.0-openjdk-src-1.7.0.75-2.5.4.2.fc20.x86_6  |  39 MB  00:23     
--------------------------------------------------------------------------------
Total                                             4.5 MB/s | 163 MB  00:36     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction (shutdown inhibited)
  Installing : java-atk-wrapper-0.30.4-4.fc20.x86_64                       3/13 
  Installing : 1:java-1.7.0-openjdk-accessibility-1.7.0.75-2.5.4.2.fc20    4/13 
  Installing : 1:java-1.7.0-openjdk-devel-1.7.0.75-2.5.4.2.fc20.x86_64     9/13 
  Installing : 1:java-1.7.0-openjdk-src-1.7.0.75-2.5.4.2.fc20.x86_64      10/13 
  Installing : 1:java-1.7.0-openjdk-javadoc-1.7.0.75-2.5.4.2.fc20.noarc   12/13 
  Installing : 1:java-1.7.0-openjdk-demo-1.7.0.75-2.5.4.2.fc20.x86_64     13/13 
  Verifying  : 1:java-1.7.0-openjdk-demo-1.7.0.75-2.5.4.2.fc20.x86_64      2/13 
  Verifying  : 1:java-1.7.0-openjdk-javadoc-1.7.0.75-2.5.4.2.fc20.noarc    3/13 
  Verifying  : java-atk-wrapper-0.30.4-4.fc20.x86_64                       5/13 
  Verifying  : 1:java-1.7.0-openjdk-accessibility-1.7.0.75-2.5.4.2.fc20    6/13 
  Verifying  : 1:java-1.7.0-openjdk-devel-1.7.0.75-2.5.4.2.fc20.x86_64     8/13 
  Verifying  : 1:java-1.7.0-openjdk-src-1.7.0.75-2.5.4.2.fc20.x86_64      12/13 
 
Installed:
  java-1.7.0-openjdk-accessibility.x86_64 1:1.7.0.75-2.5.4.2.fc20               
  java-1.7.0-openjdk-demo.x86_64 1:1.7.0.75-2.5.4.2.fc20                        
  java-1.7.0-openjdk-devel.x86_64 1:1.7.0.75-2.5.4.2.fc20                       
  java-1.7.0-openjdk-javadoc.noarch 1:1.7.0.75-2.5.4.2.fc20                     
  java-1.7.0-openjdk-src.x86_64 1:1.7.0.75-2.5.4.2.fc20                         
 
Dependency Installed:
  java-atk-wrapper.x86_64 0:0.30.4-4.fc20                                       
 
Complete!

You can find the Java compiler’s version with the following command:

javac -version

It should show you the following Java version:

javac 1.7.0_75

Next, you need to install the mysql-connector-java library with yum like this:

yum install -y mysql-connector-java

It should generate the following installation output:

Loaded plugins: langpacks, refresh-packagekit
mysql-connectors-community                                  | 2.5 kB  00:00     
mysql-tools-community                                       | 2.5 kB  00:00     
mysql56-community                                           | 2.5 kB  00:00     
pgdg93                                                      | 3.6 kB  00:00     
updates/20/x86_64/metalink                                  |  15 kB  00:00     
Resolving Dependencies
--> Running transaction check
---> Package mysql-connector-java.noarch 1:5.1.28-1.fc20 will be installed
--> Processing Dependency: jta >= 1.0 for package: 1:mysql-connector-java-5.1.28-1.fc20.noarch
--> Processing Dependency: slf4j for package: 1:mysql-connector-java-5.1.28-1.fc20.noarch
--> Running transaction check
---> Package geronimo-jta.noarch 0:1.1.1-15.fc20 will be installed
---> Package slf4j.noarch 0:1.7.5-3.fc20 will be installed
--> Processing Dependency: mvn(log4j:log4j) for package: slf4j-1.7.5-3.fc20.noarch
--> Processing Dependency: mvn(javassist:javassist) for package: slf4j-1.7.5-3.fc20.noarch
--> Processing Dependency: mvn(commons-logging:commons-logging) for package: slf4j-1.7.5-3.fc20.noarch
--> Processing Dependency: mvn(commons-lang:commons-lang) for package: slf4j-1.7.5-3.fc20.noarch
--> Processing Dependency: mvn(ch.qos.cal10n:cal10n-api) for package: slf4j-1.7.5-3.fc20.noarch
--> Running transaction check
---> Package apache-commons-lang.noarch 0:2.6-13.fc20 will be installed
---> Package apache-commons-logging.noarch 0:1.1.3-8.fc20 will be installed
--> Processing Dependency: mvn(logkit:logkit) for package: apache-commons-logging-1.1.3-8.fc20.noarch
--> Processing Dependency: mvn(avalon-framework:avalon-framework-api) for package: apache-commons-logging-1.1.3-8.fc20.noarch
---> Package cal10n.noarch 0:0.7.7-3.fc20 will be installed
---> Package javassist.noarch 0:3.16.1-6.fc20 will be installed
---> Package log4j.noarch 0:1.2.17-14.fc20 will be installed
--> Processing Dependency: mvn(org.apache.geronimo.specs:geronimo-jms_1.1_spec) for package: log4j-1.2.17-14.fc20.noarch
--> Processing Dependency: mvn(javax.mail:mail) for package: log4j-1.2.17-14.fc20.noarch
--> Running transaction check
---> Package avalon-framework.noarch 0:4.3-9.fc20 will be installed
--> Processing Dependency: xalan-j2 for package: avalon-framework-4.3-9.fc20.noarch
---> Package avalon-logkit.noarch 0:2.1-13.fc20 will be installed
--> Processing Dependency: tomcat-servlet-3.0-api for package: avalon-logkit-2.1-13.fc20.noarch
---> Package geronimo-jms.noarch 0:1.1.1-17.fc20 will be installed
---> Package javamail.noarch 0:1.5.0-6.fc20 will be installed
--> Running transaction check
---> Package tomcat-servlet-3.0-api.noarch 0:7.0.52-2.fc20 will be installed
---> Package xalan-j2.noarch 0:2.7.1-22.fc20 will be installed
--> Processing Dependency: xerces-j2 for package: xalan-j2-2.7.1-22.fc20.noarch
--> Processing Dependency: osgi(org.apache.xerces) for package: xalan-j2-2.7.1-22.fc20.noarch
--> Running transaction check
---> Package xerces-j2.noarch 0:2.11.0-17.fc20 will be installed
--> Processing Dependency: xml-commons-resolver >= 1.2 for package: xerces-j2-2.11.0-17.fc20.noarch
--> Processing Dependency: xml-commons-apis >= 1.4.01 for package: xerces-j2-2.11.0-17.fc20.noarch
--> Processing Dependency: osgi(org.apache.xml.resolver) for package: xerces-j2-2.11.0-17.fc20.noarch
--> Processing Dependency: osgi(javax.xml) for package: xerces-j2-2.11.0-17.fc20.noarch
--> Running transaction check
---> Package xml-commons-apis.noarch 0:1.4.01-14.fc20 will be installed
---> Package xml-commons-resolver.noarch 0:1.2-14.fc20 will be installed
--> Finished Dependency Resolution
 
Dependencies Resolved
 
================================================================================
 Package                    Arch       Version                Repository   Size
================================================================================
Installing:
 mysql-connector-java       noarch     1:5.1.28-1.fc20        updates     1.3 M
Installing for dependencies:
 apache-commons-lang        noarch     2.6-13.fc20            fedora      281 k
 apache-commons-logging     noarch     1.1.3-8.fc20           updates      78 k
 avalon-framework           noarch     4.3-9.fc20             fedora       87 k
 avalon-logkit              noarch     2.1-13.fc20            fedora       87 k
 cal10n                     noarch     0.7.7-3.fc20           fedora       37 k
 geronimo-jms               noarch     1.1.1-17.fc20          fedora       32 k
 geronimo-jta               noarch     1.1.1-15.fc20          fedora       21 k
 javamail                   noarch     1.5.0-6.fc20           fedora      606 k
 javassist                  noarch     3.16.1-6.fc20          fedora      626 k
 log4j                      noarch     1.2.17-14.fc20         fedora      449 k
 slf4j                      noarch     1.7.5-3.fc20           fedora      173 k
 tomcat-servlet-3.0-api     noarch     7.0.52-2.fc20          updates     207 k
 xalan-j2                   noarch     2.7.1-22.fc20          updates     1.9 M
 xerces-j2                  noarch     2.11.0-17.fc20         updates     1.1 M
 xml-commons-apis           noarch     1.4.01-14.fc20         fedora      227 k
 xml-commons-resolver       noarch     1.2-14.fc20            fedora      108 k
 
Transaction Summary
================================================================================
Install  1 Package (+16 Dependent packages)
 
Total download size: 7.3 M
Installed size: 10 M
Downloading packages:
(1/17): apache-commons-logging-1.1.3-8.fc20.noarch.rpm      |  78 kB  00:00     
(2/17): apache-commons-lang-2.6-13.fc20.noarch.rpm          | 281 kB  00:00     
(3/17): avalon-framework-4.3-9.fc20.noarch.rpm              |  87 kB  00:00     
(4/17): avalon-logkit-2.1-13.fc20.noarch.rpm                |  87 kB  00:00     
(5/17): cal10n-0.7.7-3.fc20.noarch.rpm                      |  37 kB  00:00     
(6/17): geronimo-jms-1.1.1-17.fc20.noarch.rpm               |  32 kB  00:00     
(7/17): geronimo-jta-1.1.1-15.fc20.noarch.rpm               |  21 kB  00:00     
(8/17): javamail-1.5.0-6.fc20.noarch.rpm                    | 606 kB  00:00     
(9/17): javassist-3.16.1-6.fc20.noarch.rpm                  | 626 kB  00:00     
(10/17): log4j-1.2.17-14.fc20.noarch.rpm                    | 449 kB  00:00     
(11/17): slf4j-1.7.5-3.fc20.noarch.rpm                      | 173 kB  00:00     
(12/17): mysql-connector-java-5.1.28-1.fc20.noarch.rpm      | 1.3 MB  00:01     
(13/17): tomcat-servlet-3.0-api-7.0.52-2.fc20.noarch.rpm    | 207 kB  00:00     
(14/17): xalan-j2-2.7.1-22.fc20.noarch.rpm                  | 1.9 MB  00:00     
(15/17): xerces-j2-2.11.0-17.fc20.noarch.rpm                | 1.1 MB  00:00     
(16/17): xml-commons-apis-1.4.01-14.fc20.noarch.rpm         | 227 kB  00:00     
(17/17): xml-commons-resolver-1.2-14.fc20.noarch.rpm        | 108 kB  00:00     
--------------------------------------------------------------------------------
Total                                              1.3 MB/s | 7.3 MB  00:05     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction (shutdown inhibited)
  Installing : xml-commons-apis-1.4.01-14.fc20.noarch                      1/17 
  Installing : geronimo-jms-1.1.1-17.fc20.noarch                           2/17 
  Installing : xml-commons-resolver-1.2-14.fc20.noarch                     3/17 
  Installing : xerces-j2-2.11.0-17.fc20.noarch                             4/17 
  Installing : xalan-j2-2.7.1-22.fc20.noarch                               5/17 
  Installing : javamail-1.5.0-6.fc20.noarch                                6/17 
  Installing : log4j-1.2.17-14.fc20.noarch                                 7/17 
  Installing : tomcat-servlet-3.0-api-7.0.52-2.fc20.noarch                 8/17 
  Installing : avalon-framework-4.3-9.fc20.noarch                          9/17 
  Installing : avalon-logkit-2.1-13.fc20.noarch                           10/17 
  Installing : apache-commons-logging-1.1.3-8.fc20.noarch                 11/17 
  Installing : javassist-3.16.1-6.fc20.noarch                             12/17 
  Installing : cal10n-0.7.7-3.fc20.noarch                                 13/17 
  Installing : apache-commons-lang-2.6-13.fc20.noarch                     14/17 
  Installing : slf4j-1.7.5-3.fc20.noarch                                  15/17 
  Installing : geronimo-jta-1.1.1-15.fc20.noarch                          16/17 
  Installing : 1:mysql-connector-java-5.1.28-1.fc20.noarch                17/17 
  Verifying  : geronimo-jta-1.1.1-15.fc20.noarch                           1/17 
  Verifying  : geronimo-jms-1.1.1-17.fc20.noarch                           2/17 
  Verifying  : xalan-j2-2.7.1-22.fc20.noarch                               3/17 
  Verifying  : apache-commons-lang-2.6-13.fc20.noarch                      4/17 
  Verifying  : slf4j-1.7.5-3.fc20.noarch                                   5/17 
  Verifying  : log4j-1.2.17-14.fc20.noarch                                 6/17 
  Verifying  : avalon-framework-4.3-9.fc20.noarch                          7/17 
  Verifying  : xerces-j2-2.11.0-17.fc20.noarch                             8/17 
  Verifying  : cal10n-0.7.7-3.fc20.noarch                                  9/17 
  Verifying  : avalon-logkit-2.1-13.fc20.noarch                           10/17 
  Verifying  : 1:mysql-connector-java-5.1.28-1.fc20.noarch                11/17 
  Verifying  : xml-commons-resolver-1.2-14.fc20.noarch                    12/17 
  Verifying  : xml-commons-apis-1.4.01-14.fc20.noarch                     13/17 
  Verifying  : javassist-3.16.1-6.fc20.noarch                             14/17 
  Verifying  : tomcat-servlet-3.0-api-7.0.52-2.fc20.noarch                15/17 
  Verifying  : javamail-1.5.0-6.fc20.noarch                               16/17 
  Verifying  : apache-commons-logging-1.1.3-8.fc20.noarch                 17/17 
 
Installed:
  mysql-connector-java.noarch 1:5.1.28-1.fc20                                   
 
Dependency Installed:
  apache-commons-lang.noarch 0:2.6-13.fc20                                      
  apache-commons-logging.noarch 0:1.1.3-8.fc20                                  
  avalon-framework.noarch 0:4.3-9.fc20                                          
  avalon-logkit.noarch 0:2.1-13.fc20                                            
  cal10n.noarch 0:0.7.7-3.fc20                                                  
  geronimo-jms.noarch 0:1.1.1-17.fc20                                           
  geronimo-jta.noarch 0:1.1.1-15.fc20                                           
  javamail.noarch 0:1.5.0-6.fc20                                                
  javassist.noarch 0:3.16.1-6.fc20                                              
  log4j.noarch 0:1.2.17-14.fc20                                                 
  slf4j.noarch 0:1.7.5-3.fc20                                                   
  tomcat-servlet-3.0-api.noarch 0:7.0.52-2.fc20                                 
  xalan-j2.noarch 0:2.7.1-22.fc20                                               
  xerces-j2.noarch 0:2.11.0-17.fc20                                             
  xml-commons-apis.noarch 0:1.4.01-14.fc20                                      
  xml-commons-resolver.noarch 0:1.2-14.fc20                                     
 
Complete!

I must write too much Java code for the Windows platform because I didn’t notice the change in how the DriverManager should be instantiated. Initially, I wrote the program using the following declaration for the DriverManager class:

30
      DriverManager.registerDriver(new com.mysql.jdbc.Driver());

While it worked on Windows, the same syntax in the MySQL.java program raised two errors on the Linux server. One for the declaration of the com.mysql.jdbc.Driver class and another trying to declare an instance of Driver class.

These are the two errors:

MySQL.java:5: error: package com.mysql.jdbc does not exist
import com.mysql.jdbc.Driver;
                     ^
MySQL.java:31: error: package com.mysql.jdbc does not exist
      DriverManager.registerDriver(new com.mysql.jdbc.Driver());
                                                     ^

I rewrote the MySQL.java program as follows, and it works on both implementations:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
// Import classes.
import java.sql.*;
 
/* You can't include the following on Linux without raising an exception. */
// import com.mysql.jdbc.Driver;
 
public class MySQL {
  public MySQL() {
    /* Declare variables that require explicit assignments because
       they're addressed in the finally block. */
    Connection conn = null;
    Statement stmt = null;
    ResultSet rset = null;
 
    /* Declare other variables. */
    String url;
    String username = "student";
    String password = "student";
    String database = "studentdb";
    String hostname = "localhost";
    String port = "3306";
    String sql;
 
    /* Attempt a connection. */
    try {
      // Set URL.
      url = "jdbc:mysql://" + hostname + ":" + port + "/" + database;
 
      // Create instance of MySQL.
      Class.forName ("com.mysql.jdbc.Driver").newInstance();
      conn = DriverManager.getConnection (url, username, password);
 
      // Query the version of the database.
      sql = "SELECT version()";
      stmt = conn.createStatement();
      rset = stmt.executeQuery(sql);
 
      System.out.println ("Database connection established");
 
      // Read row returns for one column.
      while (rset.next()) {
        System.out.println("MySQL Version [" + rset.getString(1) + "]"); }
 
    }
    catch (SQLException e) {
      System.err.println ("Cannot connect to database server:");
      System.out.println(e.getMessage());
    }
    catch (ClassNotFoundException e) {
      System.err.println ("Cannot connect to database server:");
      System.out.println(e.getMessage());
    }
    catch (InstantiationException e) {
      System.err.println ("Cannot connect to database server:");
      System.out.println(e.getMessage());
    }
    catch (IllegalAccessException e) {
      System.err.println ("Cannot connect to database server:");
      System.out.println(e.getMessage());
    }
    finally {
      if (conn != null) {
        try {
          rset.close();
          stmt.close();
          conn.close();
          System.out.println ("Database connection terminated");
        }
        catch (Exception e) { /* ignore close errors */ }
      }
    }
  }
  /* Unit test. */
  public static void main(String args[]) {
    new MySQL();
  }
}

The old approach to the DriverManager and Driver classes disallows the use of three of the exceptions in the sample code: ClassNotFoundException, InstantiationException, and IllegalAccessException classes. The new syntax works on Linux, Mac OS X, and Windows. If you’re running on Mac OS X, you need to import the following additional library in the MySQL.java program:

import com.apple.eawt.*;

Before you compile the MySQL.java program, you need to put the mysql-connector-java.jar and your present working directory into your environment’s $CLASSPATH variable. You can set the $CLASSPATH variable at the command-line or embed the following in your .bashrc file:

export CLASSPATH=/usr/share/java/mysql-connector-java.jar:.

If you embedded it in the .bashrc file, you need to source that file or restart your terminal session, which resources the .bashrc for you. You can source your .bashrc file from an active Terminal session in your home directory with this syntax:

. ./.bashrc

If you’re new to Java and the MySQL Connector/J, you compile the MySQL.java program with the following syntax. At least, it works when you have the MySQL.java source file in the present working directory and want to create the class file in the same directory. You can find more about the javac command-line at the www.tutorialpoint.com web site>

javac -verbose -cp . MySQL.java

Then, you can run it with the class file with this syntax:

java MySQL

It should return the following:

Database connection established
MySQL Version [5.6.24]
Database connection terminated

If you’d prefer to return data, you can replace line 34 in the MySQL.java program with a query against a table, like:

34
      sql = "SELECT item_title, item_rating FROM item";

Then, change line 42 in the MySQL.java program with syntax to manage the output, like:

42
        System.out.println(rset.getString(1) + ", " + rset.getString(2)); }

Recompile it, and rerun the MySQL class file with this syntax:

java MySQL

It should return the following:

Database connection established
The Hunt for Red October, PG
Star Wars I, PG
Star Wars II, PG
Star Wars II, PG
Star Wars III, PG13
The Chronicles of Narnia, PG
RoboCop, Mature
Pirates of the Caribbean, Teen
The Chronicles of Narnia, Everyone
MarioKart, Everyone
Splinter Cell, Teen
Need for Speed, Everyone
The DaVinci Code, Teen
Cars, Everyone
Beau Geste, PG
I Remember Mama, NR
Tora! Tora! Tora!, G
A Man for All Seasons, G
Hook, PG
Around the World in 80 Days, G
Harry Potter and the Chamber of Secrets, PG
Camelot, G
Database connection terminated

As always, I hope this helps those looking for a solution.

Written by maclochlainn

April 17th, 2015 at 5:16 pm

Popular Programming Languages

with 6 comments

First of all, Happy New Year!

IEEE Spectrum published a ranking of the most popular programming languages. Computational journalist Nick Diakopoulos wrote the article. While it may surprise some, I wasn’t surprised to find SQL in the top ten.

07dataflow-1403643424680Nick weighted and combined 12 metrics from 10 sources (including IEEE Xplore, Google, and GitHub) to rank the most popular programming languages.

  • Compiled programming languages (Java [#1], C [#2], C++ [#3], C# [#4], Objective-C [#16])
  • Interpreted programming languages (Python [#5], JavaScript [#6], PHP [#7], Ruby [#8], Perl [#11], HTML [#12])
  • Data languages (SQL [#9], MATLAB [#10], R [#13])

I couldn’t resist including Objective-C because it shows how the iPhone, iPad, and Mac OS impact our daily lives. At the same time, Assembly [#15] is actually more popular than Objective-C. Shell [#17] follows Objective-C. While the Visual Basic [#14] programming language still remains very popular.

There are many “why” questions raised by this list of popular programming languages. The “why” from my perspective deals with what are the market drivers for their popularity. The money drivers I see are as follows:

Business Intelligence (BI) software manages most high-level data analysis tools and they’ll continue to get better over time. However, if SQL has shown us anything over 30 years it’s that ultimately we revert to it to solve problems. The conclusion from the reality of BI probably means the programming languages that develop those tools will continue to rise and so will the underlying data languages.

It’s also interesting to note that nine out of ten of the popular programming languages work with databases, like Oracle, MySQL, PostgreSQL, or SQL Server. While JavaScript doesn’t access the database typically, it’s JSON (JavaScript Object Notation) is supported in all the databases.

Written by maclochlainn

January 1st, 2015 at 9:46 pm

Hiding a Java Source

with one comment

The ability to deploy Java inside the Oracle database led somebody to conclude that the source isn’t visible in the data catalog. Then, that person found that they were wrong because the Java source is visible when you use a DDL command to CREATE, REPLACE, and COMPILE the Java source. This post discloses how to find the Java source and how to prevent it from being stored in the data catalog.

You can verify that the Java class and source files exist with the following query:

1
2
3
4
5
6
7
8
COLUMN object_name FORMAT A20 HEADING "Object Name"
COLUMN object_type FORMAT A12 HEADING "Object Type"
COLUMN status      FORMAT A14 HEADING "Object Status"
SELECT   object_name
,        object_type
,        status
FROM     user_objects
WHERE    object_name = 'ReadFile';

It displays:

Object Name          Object Type  Object Status
-------------------- ------------ --------------
ReadFile             JAVA SOURCE  VALID
ReadFile             JAVA CLASS   VALID
 
2 rows selected.

Then, you can use the following query to discovery a Java library created by a SQL command:

1
2
3
4
5
6
COLUMN line FORMAT 9999 HEADING "Line|#"
COLUMN text FORMAT A66  HEADING "Text"
SELECT   line
,        text
FROM     user_source
WHERE    name = 'ReadFile';

It displays the following:

 Line # Text
------- ------------------------------------------------------------------
    1   // Java library imports.
    2   import java.io.File;
    3   import java.io.BufferedReader;
    4   import java.io.FileNotFoundException;
    5   import java.io.IOException;
    6   import java.io.FileReader;
    7   import java.security.AccessControlException;
    8
    9   // Class definition.
   10   public class ReadFile {
   11     // Define class variables.
   12     private static File file;
   13     private static FileReader inTextFile;
   14     private static BufferedReader inTextReader;
   15     private static StringBuffer output = new StringBuffer();
   16     private static String outLine, outText;
   17
   18     // Define readText() method.
   19     public static String readText(String fromFile)
   20       throws AccessControlException, IOException {
   21       // Read file.
   22       try {
   23         // Initialize File.
   24         file = new File(fromFile);
   25
   26         // Check for valid file.
   27         if (file.exists()) {
   28
   29           // Assign file to a stream.
   30           inTextFile = new FileReader(file);
   31           inTextReader = new BufferedReader(inTextFile);
   32
   33           // Read character-by-character.
   34           while ((outLine = inTextReader.readLine()) != null) {
   35             output.append(outLine + "\n"); }
   36
   37           // Assing the StringBuffer to a String.
   38           outText = Integer.toString(output.toString().length());
   39
   40           // Close File.
   41           inTextFile.close(); }
   42         else {
   43           outText = new String("Empty"); }}
   44       catch (IOException e) {
   45         outText = new String("");
   46         return outText; }
   47     return outText; }}
 
47 rows selected.

You can eliminate the source by compiling the Java library outside the database. Then, you use the loadjava utility to load the only the class file into the data catalog. The syntax would be the following command for an importer user in a video Pluggable Database (PDB):

loadjava -r -f -o -user importer/importer@video ReadFile.class

You should know that this syntax is disallowed by the loadjava utility, notwithstanding it’s found in the Oracle Database 12c documentation:

loadjava -r -f -o -user importer@video/importer ReadFile.class

You can verify that only the Java class file exists with the following query:

1
2
3
4
5
6
7
8
COLUMN object_name FORMAT A20 HEADING "Object Name"
COLUMN object_type FORMAT A12 HEADING "Object Type"
COLUMN status      FORMAT A14 HEADING "Object Status"
SELECT   object_name
,        object_type
,        status
FROM     user_objects
WHERE    object_name = 'ReadFile';

It displays:

Object Name          Object Type  Object Status
-------------------- ------------ --------------
ReadFile             JAVA CLASS   VALID
 
1 row selected.

Hope this helps those who want to hide the Java source files.

Written by maclochlainn

July 22nd, 2014 at 10:23 pm

Java File IO & NIO2

without comments

Java 6, or the java.io.* package which has been around a long time has known limits. There are some noted issues with the Java 6 java.io.* package, and why I wrote the FileIO.java file back in 2002. The FileIO.java class creates a series of static methods that let you read, write, copy, and move files both locally and across the network.

  • Many methods fail to throw exceptions
  • A number of simple methods are missing, like the copy and move methods
  • There isn’t any support for symbolic links
  • Many methods fail to scale with large files

The Java 7 introduces the java.nio.file.* package, and it does the following:

  • Works more consistently across platforms
  • Provides improved access to more file attributes
  • Provides improved exception handling
  • Supports non-native file systems

A student asked me to post the FileIO.java file. So, I posted it on the github.com site. I hope it helps simplifies the use of File IO operations. Admittedly, it’s easier to read and write a file with Java 7. The following provides a complete example class:

import java.awt.Dimension;
import java.awt.Font;
import java.io.*;
import java.nio.file.*;
import java.nio.charset.Charset;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
 
public class ReadWriteFile {
 
    // Constructor for objects of class ReadFile
    public ReadWriteFile() {}
 
  // Write a file.
  public static void writeFile(String fileName, String fileText) {
    // Declare a file path.
    Path p = Paths.get(fileName);
 
    // Write a file.
    try {
      BufferedWriter bw =
        Files.newBufferedWriter( p, Charset.forName("ISO-8859-1")
                                  , StandardOpenOption.CREATE, StandardOpenOption.APPEND );
      bw.write(fileText, 0, fileText.length());
      bw.close(); }
    catch(IOException ioe) {
      System.out.println("Error writing a file."); 
      System.exit(0); }}
 
  // Read a file.
  public static String readFile(String fileName) {
    // Declare a String to hold the file.
    String text = "", line = "";
 
    // Declare a file path.
    Path p = Paths.get(fileName);
 
    // Write a file.
    try {
      // Read the file.
      BufferedReader fileInput =
        Files.newBufferedReader(p,Charset.forName("ISO-8859-1"));
 
      // Read and process first line.
      line = fileInput.readLine();
      text = line + "\n";
 
      // Read and process second thru last lines.
      while (line != null) {
        line = fileInput.readLine();
        if (line != null)
          text += line + "\n"; }
 
      // Close the file input.
      fileInput.close(); }
    catch(EOFException eofe) {
        System.out.println("No more lines to read.");
        System.exit(0); }
    catch(IOException ioe) {
        System.out.println("Error reading file."); 
        System.exit(0); }
 
    // Return a String value.
    return text;
  }
 
  // Declare a static main to read a text file.
  public static void main(String[] args) {
    // Declare local object types.
    JOptionPane op = new JOptionPane();
    JScrollPane sp;
    JTextArea ta;
    Object[] options = {};
 
    // Instantiate a test class.
    ReadWriteFile rwf = new ReadWriteFile();
 
    // Text the readFile method.
    if (args.length > 0) {
      // Set the value and formatting of the text area.
      ta = new JTextArea(rwf.readFile(args[0]));
      ta.setFont(new Font(Font.SANS_SERIF,Font.PLAIN,14));
      ta.setLineWrap(true);
      ta.setWrapStyleWord(true);
 
      // Assign the text area to a scroll pane.
      sp = new JScrollPane(ta);
      sp.setPreferredSize(new Dimension(400,200));
 
      // Invoke a generic option pane.
      op.showOptionDialog(null, sp, "File Content", JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE, null, options, null); }
 
    // Test the writeFile method.  
    if (args.length > 1) {
      rwf.writeFile(args[1],rwf.readFile(args[0])); }
  }
}

You can call it like this to read and write an output.txt file from any directory:

java ReadWriteFile Fellowship.txt output.txt

It will display a JOptionDialog like this:

JavaNIO2TextFile

Any suggestions or improvements are welcome.

Written by maclochlainn

May 18th, 2014 at 12:31 pm

Posted in Java,Java 7

Tagged with , ,

Oracle 12c VARCHAR2?

without comments

The Oracle Database 12c documentation says you can set the maximum size of a VARCHAR2 to 32,767 bytes. That’s true except when you’re trying to map a large Java string to a VARCHAR2. It fails when the physical size of the Java string is greater than 4,000 bytes with an ORA-01002 or fetch out of sequence error.

SELECT read_text_file('C:\Data\loader\Hobbit1.txt')
*
ERROR at line 1:
ORA-24345: A Truncation or null fetch error occurred
 
ERROR:
ORA-01002: fetch out of sequence

You need to grant privileges before you can test this code. You can grant privileges by connecting as the SYS user of a CDB (or non-multitenant database) or as the ADMIN user of a PDB with the AS SYSDBA clause. Then, you run the following command to grant external file access to the JVM inside Oracle Database 12c:

BEGIN
  DBMS_JAVA.GRANT_PERMISSION('IMPORTER'
                            ,'SYS:java.io.FilePermission'
                            ,'C:\Data\Loader\Hobbit1.txt'
                            ,'read');
END;
/

The IMPORTER is a PDB user name, or a non-multitenant database user name. Please note that permissions must be granted on each physical file.

Here’s the code that raises the error when the external file is greater than 4,000 bytes:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
CREATE OR REPLACE AND COMPILE JAVA SOURCE NAMED "ReadFile" AS
  // Java library imports.
  import java.io.File;
  import java.io.BufferedReader;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.FileReader;
  import java.security.AccessControlException;
 
  // Class definition.  
  public class ReadFile {
    // Define class variables.
    private static File file;
    private static FileReader inTextFile;
    private static BufferedReader inTextReader;
    private static StringBuffer output = new StringBuffer();
    private static String outLine, outText;
 
    // Define readText() method.
    public static String readText(String fromFile)
      throws AccessControlException, IOException {
      // Read file.
      try {
        // Initialize File.
        file = new File(fromFile);
 
        // Check for valid file.
        if (file.exists()) {
 
          // Assign file to a stream.          
          inTextFile = new FileReader(file);
          inTextReader = new BufferedReader(inTextFile);
 
          // Read character-by-character.
          while ((outLine = inTextReader.readLine()) != null) {
            output.append(outLine + "\n"); }
 
          // Assing the StringBuffer to a String.
          outText = output.toString();
 
          // Close File.
          inTextFile.close(); }
        else {
          outText = new String("Empty"); }}
      catch (IOException e) {
        outText = new String("");
        return outText; }
    return outText; }}
/

The PL/SQL wrapper should look like this:

1
2
3
4
5
CREATE OR REPLACE FUNCTION read_text_file
(from_file VARCHAR2) RETURN VARCHAR2 IS
LANGUAGE JAVA
NAME 'ReadFile.readText(java.lang.String) return java.lang.String';
/

Then, you can query it like so:

SELECT read_text_file('C:\Data\loader\Hobbit1.txt')
FROM dual;

You can avoid the error by returning the Java file size as a CLOB data type with the following Java source code.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
CREATE OR REPLACE AND COMPILE JAVA SOURCE NAMED "ReadFile" AS
  // Java library imports.
  import java.io.File;
  import java.io.BufferedReader;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.FileReader;
  import java.security.AccessControlException;
  import java.sql.*;
  import oracle.sql.driver.*;
  import oracle.sql.*;
 
  // Class definition.  
  public class ReadFile {
    // Define class variables.
    private static int i;
    private static File file;
    private static FileReader inTextFile;
    private static BufferedReader inTextReader;
    private static StringBuffer output = new StringBuffer();
    private static String outLine, outText;
    private static CLOB outCLOB;
 
    // Define readText() method.
    public static oracle.sql.CLOB readText(String fromFile)
      throws AccessControlException, IOException, SQLException  {
      // Read file.
      try {
        // Initialize File.
        file = new File(fromFile);
 
        // Check for valid file.
        if (file.exists()) {
 
          // Assign file to a stream.          
          inTextFile = new FileReader(file);
          inTextReader = new BufferedReader(inTextFile);
 
          // Read character-by-character.
          while ((outLine = inTextReader.readLine()) != null) {
            output.append(outLine + "\n"); }
 
          // Assing the StringBuffer to a String.
          outText = output.toString();
 
          // Declare an Oracle connection.
          Connection conn = DriverManager.getConnection("jdbc:default:connection:");
 
          // Transfer the String to CLOB.
          outCLOB = CLOB.createTemporary((oracle.jdbc.OracleConnectionWrapper) conn, true, CLOB.DURATION_SESSION);
          i = outCLOB.setString(1,outText);
 
          // Close File.
          inTextFile.close(); }
        else {
          i = outCLOB.setString(1,"Empty"); }}
      catch (IOException e) {
        i = outCLOB.setString(1,"");
        return outCLOB; }
    return outCLOB; }}
/

The wrapper changes to return a CLOB and map a java.sql.CLOB as the return type of the Java library. This command works:

1
2
3
4
5
CREATE OR REPLACE FUNCTION read_clob_file
(from_file VARCHAR2) RETURN CLOB IS
LANGUAGE JAVA
NAME 'ReadFile.readText(java.lang.String) return oracle.sql.CLOB';
/

You now query the PL/SQL wrapper with this type of effective SQL*Plus command-line command:

COLUMN atext FORMAT A60 HEADING "Text"
COLUMN asize FORMAT 99,999 HEADING "Size"
 
SELECT   read_clob_file('C:\Data\loader\Hobbit1.txt') AS AText
,        LENGTH(read_clob_file('C:\Data\loader\Hobbit1.txt')) AS ASize
FROM dual;

As always, I hope this helps somebody.

Written by maclochlainn

May 7th, 2014 at 3:03 am

DBMS_JAVA Privilege Error?

without comments

It’s possible to get an error after granting privileges to an external file system. One of those errors is tedious to resolve until you understand the rules governing Java NIO file permissions.

You grant privileges to external file systems as the sys user with the grant_permission procedure of the dbms_java package, like

SQL> BEGIN
  2    DBMS_JAVA.GRANT_PERMISSION('IMPORTER'
  3                               ,'SYS:java.io.FilePermission'
  4                               ,'C:\Data\Upload'
  5                               ,'read');
  6  END;
  7  /

After you grant privileges to read, write, and delete files with Oracle’s dbms_java package, you must disconnect any active session to enjoy the new privileges. If you forget to disconnect and re-connect an active session, you get the following error message:

FROM     TABLE(list_files(get_directory_path('STAGE')))
               *
ERROR AT line 2:
ORA-29532: JAVA CALL terminated BY uncaught JAVA EXCEPTION:
JAVA.security.AccessControlException: DIRECTORY permissions restricted.

The problem and fix are simple. The permissions aren’t in effect until after you disconnect and reconnect your active sessions. I put this there because when I Google’d it, there wasn’t an answer already.

While I’m on the topic of privilege errors, that aren’t really errors, I thought it would be helpful to qualify how the delete permission works because I couldn’t find it anywhere in the Oracle documentation (if somebody finds it let make a comment that enriches the discussion). Unlike the read and write permissions, the delete permission requires permissions on specific files.

If you only grant permission on like:

SQL> BEGIN
  2    DBMS_JAVA.GRANT_PERMISSION('IMPORTER'
  3                               ,'SYS:java.io.FilePermission'
  4                               ,'C:\Data\Upload'
  5                               ,'read,write,delete');
  6  END;
  7  /

You would get this message when trying to delete an external file:

BEGIN
*
ERROR AT line 1:
ORA-29532: JAVA CALL terminated BY uncaught JAVA EXCEPTION:
JAVA.security.AccessControlException: the Permission (JAVA.io.FilePermission
c:\data\LOG\item_import.LOG read) has NOT been granted TO IMPORTER. The PL/SQL
TO GRANT this IS dbms_java.grant_permission( 'IMPORTER',
'SYS:java.io.FilePermission', 'c:\data\log\item_import.log', 'read' )
ORA-06512: AT "IMPORTER.DELETE_FILE", line 1
ORA-06512: AT line 2

It requires that you grant permissions on individual files to have the privilege of deleting them from within Oracle. That grant would look like the following:

SQL> BEGIN
  2    DBMS_JAVA.GRANT_PERMISSION('IMPORTER'
  3                               ,'SYS:java.io.FilePermission'
  4                               ,'C:\Data\Upload\item_import.log'
  5                               ,'read,write,delete');
  6  END;
  7  /

As always, I hope this helps other developers.

Written by maclochlainn

March 29th, 2014 at 1:59 pm

Hidden DBMS_JAVA Nuance

without comments

It always happens when I’m in a hurry. Yes, I ran into one of those pesky little features with Oracle’s DBMS_JAVA package. While I try to write entries with proper GeSHi case semantics, like everyone else I tend to write PL/SQL initially in lowercase. That led me to the discovery of this wonderful error message:

BEGIN
*
ERROR at line 1:
ORA-29532: Java CALL TERMINATED BY uncaught Java exception:
oracle.aurora.vm.IdNotFoundException: importer : USER OR ROLE id does NOT exist
ORA-06512: at "SYS.DBMS_JAVA", line 705
ORA-06512: at line 2

The problem was simple, while not published, you must enter the user/schema name in uppercase text when calling DBMS_JAVA.GRANT_PERMISSION procedure. Here’s a proper example:

SQL> BEGIN
  2    DBMS_JAVA.GRANT_PERMISSION('IMPORTER'
  3                               ,'SYS:java.io.FilePermission'
  4                               ,'C:\Data\Upload'
  5                               ,'read');
  6  END;
  7  /

If you change the IMPORTER string to lower or mixed case, you raise the aforementioned error. Quite an interesting tidbit that I missed from Oracle Database 10g until Oracle Database 12c. Hope this helps you avoid wondering what’s happening when your line 2 looks like this:

  2    DBMS_JAVA.GRANT_PERMISSION('Importer'

As always, I hope this helps others. If you like more on writing Java inside the Oracle database you can check this older post.

Written by maclochlainn

March 21st, 2014 at 12:44 am

OOW & JavaOne 2013 Over

without comments

GoldenGateBridge2013Medium

Oracle OpenWorld 2013 and JavaOne 2013 are over and the America’s Cup a done deal. It was a full week. I didn’t have a moment to blog because I stay out in Livermore, which adds an hour plus to the beginning and ending of my day. It’s funny but I didn’t get a sense from some that they were excited about Oracle 12c. That’s probably because they don’t appear to know too much about it yet.

The Container Database (CDB) versus Pluggable Database (PDB) has enormous impact on how we can leverage Oracle in the private or public cloud. Admittedly, the ideas and concepts take some time to understand, implement, and appreciate.

Talking to folks, I got some great ideas for future blog posts.OOW13 If you have any that I should add, let me know with a comment. I think the first one will show everyone how to migrate traditional surrogate key primary key columns to Oracle 12c‘s new Identity Columns.

Having seen some presentations referencing zetta-bytes, I wondered to myself (and now blog readers): “When will the Exadata server be replaced by a Zettadata server?”

Up there on my list for new blog posts are Oracle 12c‘s new Invisible Columns and new DBMS_REDACT package. For those interested, I’ll also present at UTOUG’s Fall Symposium on October 29th, 2013 on SQL and PL/SQL New Features in the Oracle Database 12c.

It was great to see familiar faces and sad to note those missing. Somehow the energy in Dell’s demo ground didn’t quite replace the old Quest Software demo ground’s pizazz.

Once home, I had to pivot back to task. I’m copy editing the Oracle Database 12c Programming PL/SQL Programming book, which will release in February 2014.

If you’re wondering about the photo of the Golden Gate Bridge, my son Joseph took it with his new iPhone 5s. I’m looking forward to my own iPhoneĀ upgrade in November. šŸ˜‰

Written by maclochlainn

September 30th, 2013 at 11:55 pm