Archive for the ‘Java Developer’ tag
AlmaLinux Install & Configuration
This is a collection of blog posts for installing and configuring AlmaLinux with the Oracle, PostgreSQL, MySQL databases and several programming languages. Sample programs show how to connect PHP and Python to the MySQL database.
- Installing AlmaLinux operating system
- Installing and configuring MySQL
- Installing Python-MySQL connector and provide sample programs
- Configuring Flask for Python on AlmaLinux with a complete software router instruction set.
- Installing Rust programming language and writing a sample program
- Installing and configuring LAMP stack with PHP and MySQL and a self-signed security key
- MySQL PNG Images in LAMP with PHP Programming
- Demonstration of how to write Perl that connects to MySQL
- Installing and configuring MySQL Workbench
- Installing and configuring PostgreSQL and pgAdmin4
- Identifying the required libnsl2-devel packages for SQL*Plus
- Writing and deploying a sqlplus function to use a read line wrapper
- Installing and configuring Visual Studio Code Editor
- Installing and configuring Java with connectivity to MySQL
- Installing and configuring Oracle SQL Developer
I used Oracle Database 11g XE in this instance to keep the footprint as small as possible. It required a few tricks and discovering the missing library that caused folks grief eleven years ago. I build another with a current Oracle Database XE after the new year.
If you see something that I missed or you’d like me to add, let me know. As time allows, I’ll try to do that. Naturally, the post will get updates as things are added later.
AlmaLinux+Java+MySQL
AlmaLinux generally has Java installed. You can check whether java is installed with this command:
which -a java |
It should return:
/usr/bin/java |
Then, you can check the Java version with this command:
java -version |
For AlmaLinux 9, it should return:
openjdk version "11.0.17" 2022-10-18 LTS OpenJDK Runtime Environment (Red_Hat-11.0.17.0.8-2.el9_0) (build 11.0.17+8-LTS) OpenJDK 64-Bit Server VM (Red_Hat-11.0.17.0.8-2.el9_0) (build 11.0.17+8-LTS, mixed mode, sharing) |
Next, you check whether javac is installed. You can use the which command to determine whether it is installed. Generally, its not installed and you use this command to
sudo dnf search jdk | egrep -- '-17' |
It should return:
Last metadata expiration check: 0:11:17 ago on Mon 19 Dec 2022 11:32:48 PM EST. java-17-openjdk.x86_64 : OpenJDK 17 Runtime Environment java-17-openjdk-demo.x86_64 : OpenJDK 17 Demos java-17-openjdk-devel.x86_64 : OpenJDK 17 Development Environment java-17-openjdk-headless.x86_64 : OpenJDK 17 Headless Runtime Environment java-17-openjdk-javadoc.x86_64 : OpenJDK 17 API documentation java-17-openjdk-javadoc-zip.x86_64 : OpenJDK 17 API documentation compressed in a single archive java-17-openjdk-jmods.x86_64 : JMods for OpenJDK 17 java-17-openjdk-src.x86_64 : OpenJDK 17 Source Bundle java-17-openjdk-static-libs.x86_64 : OpenJDK 17 libraries for static linking |
Now, you can install the Java JDK with the following dnf command:
sudo dnf install java-17-openjdk java-17-openjdk-devel |
The log file for this is:
Display detailed console log →
Last metadata expiration check: 0:28:26 ago on Mon 19 Dec 2022 11:32:48 PM EST. Dependencies resolved. ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: java-17-openjdk x86_64 1:17.0.5.0.8-2.el9_0 appstream 237 k java-17-openjdk-devel x86_64 1:17.0.5.0.8-2.el9_0 appstream 4.7 M Installing dependencies: java-17-openjdk-headless x86_64 1:17.0.5.0.8-2.el9_0 appstream 40 M ttmkfdir x86_64 3.0.9-65.el9 appstream 52 k xorg-x11-fonts-Type1 noarch 7.5-33.el9 appstream 499 k Transaction Summary ================================================================================ Install 5 Packages Total download size: 45 M Installed size: 199 M Is this ok [y/N]: y Downloading Packages: (1/5): java-17-openjdk-17.0.5.0.8-2.el9_0.x86_6 342 kB/s | 237 kB 00:00 (2/5): ttmkfdir-3.0.9-65.el9.x86_64.rpm 520 kB/s | 52 kB 00:00 (3/5): xorg-x11-fonts-Type1-7.5-33.el9.noarch.r 849 kB/s | 499 kB 00:00 (4/5): java-17-openjdk-devel-17.0.5.0.8-2.el9_0 1.7 MB/s | 4.7 MB 00:02 (5/5): java-17-openjdk-headless-17.0.5.0.8-2.el 6.1 MB/s | 40 MB 00:06 -------------------------------------------------------------------------------- Total 6.3 MB/s | 45 MB 00:07 Running transaction check Transaction check succeeded. Running transaction test Transaction test succeeded. Running transaction Regex version mismatch, expected: 10.40 2022-04-14 actual: 10.37 2021-05-26 Regex version mismatch, expected: 10.40 2022-04-14 actual: 10.37 2021-05-26 Running scriptlet: java-17-openjdk-headless-1:17.0.5.0.8-2.el9_0.x86_64 1/1 Preparing : 1/1 Installing : java-17-openjdk-headless-1:17.0.5.0.8-2.el9_0.x86_64 1/5 Running scriptlet: java-17-openjdk-headless-1:17.0.5.0.8-2.el9_0.x86_64 1/5 Installing : ttmkfdir-3.0.9-65.el9.x86_64 2/5 Installing : xorg-x11-fonts-Type1-7.5-33.el9.noarch 3/5 Running scriptlet: xorg-x11-fonts-Type1-7.5-33.el9.noarch 3/5 Installing : java-17-openjdk-1:17.0.5.0.8-2.el9_0.x86_64 4/5 Running scriptlet: java-17-openjdk-1:17.0.5.0.8-2.el9_0.x86_64 4/5 Installing : java-17-openjdk-devel-1:17.0.5.0.8-2.el9_0.x86_64 5/5 Running scriptlet: java-17-openjdk-devel-1:17.0.5.0.8-2.el9_0.x86_64 5/5 Running scriptlet: java-17-openjdk-headless-1:17.0.5.0.8-2.el9_0.x86_64 5/5 Running scriptlet: java-17-openjdk-1:17.0.5.0.8-2.el9_0.x86_64 5/5 Running scriptlet: java-17-openjdk-devel-1:17.0.5.0.8-2.el9_0.x86_64 5/5 Verifying : java-17-openjdk-1:17.0.5.0.8-2.el9_0.x86_64 1/5 Verifying : java-17-openjdk-devel-1:17.0.5.0.8-2.el9_0.x86_64 2/5 Verifying : java-17-openjdk-headless-1:17.0.5.0.8-2.el9_0.x86_64 3/5 Verifying : ttmkfdir-3.0.9-65.el9.x86_64 4/5 Verifying : xorg-x11-fonts-Type1-7.5-33.el9.noarch 5/5 Installed: java-17-openjdk-1:17.0.5.0.8-2.el9_0.x86_64 java-17-openjdk-devel-1:17.0.5.0.8-2.el9_0.x86_64 java-17-openjdk-headless-1:17.0.5.0.8-2.el9_0.x86_64 ttmkfdir-3.0.9-65.el9.x86_64 xorg-x11-fonts-Type1-7.5-33.el9.noarch Complete! |
After installing javac, you can verify it with the which command, and check the version with the javac utility.
which -a javac |
It should return:
/usr/bin/javac |
Then, you can check the Java version with this command:
java -version |
For AlmaLinux 9, it should return:
javac 17.0.5 |
Now, you need to download and install the jdk with the dnf utility. You download the jdk package with the wget utility.
wget https://download.oracle.com/java/17/latest/jdk-17_linux-x64_bin.rpm |
It will generate the following console output:
--2022-12-20 00:12:34-- https://download.oracle.com/java/17/latest/jdk-17_linux-x64_bin.rpm Resolving download.oracle.com (download.oracle.com)... 23.192.208.88 Connecting to download.oracle.com (download.oracle.com)|23.192.208.88|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 163101336 (156M) [application/x-redhat-package-manager] Saving to: ‘jdk-17_linux-x64_bin.rpm’ jdk-17_linux-x64_bi 100%[===================>] 155.54M 11.1MB/s in 17s 2022-12-20 00:12:51 (9.01 MB/s) - ‘jdk-17_linux-x64_bin.rpm’ saved [163101336/163101336] |
You install the jdk package with the dnf utility.
sudo rpm -Uvh jdk-17_linux-x64_bin.rpm |
The log file for this is:
Display detailed console log →
warning: jdk-17_linux-x64_bin.rpm: Header V3 RSA/SHA256 Signature, key ID ec551f03: NOKEY Verifying... ################################# [100%] Regex version mismatch, expected: 10.40 2022-04-14 actual: 10.37 2021-05-26 Regex version mismatch, expected: 10.40 2022-04-14 actual: 10.37 2021-05-26 Preparing... ################################# [100%] Updating / installing... 1:jdk-17-2000:17.0.5-ga ################################# [100%] |
After installing everything, you need to set the default Java. You can discover the available Java versions with the following command:
sudo alternatives --config java |
It should return a list and the ability to select one by using the “Selection” number. I recommend you chose #2.
There are 3 programs which provide 'java'. Selection Command ----------------------------------------------- 1 java-11-openjdk.x86_64 (/usr/lib/jvm/java-11-openjdk-11.0.17.0.8-2.el9_0.x86_64/bin/java) 2 java-17-openjdk.x86_64 (/usr/lib/jvm/java-17-openjdk-17.0.5.0.8-2.el9_0.x86_64/bin/java) *+ 3 /usr/java/jdk-17.0.5/bin/java Enter to keep the current selection[+], or type selection number: 2 |
Then, you can check the Java version with this command:
java -version |
Now, it should return:
openjdk version "17.0.5" 2022-10-18 LTS OpenJDK Runtime Environment (Red_Hat-17.0.5.0.8-2.el9_0) (build 17.0.5+8-LTS) OpenJDK 64-Bit Server VM (Red_Hat-17.0.5.0.8-2.el9_0) (build 17.0.5+8-LTS, mixed mode, sharing) |
You should define the $JAVA_HOME environment variable in the /etc/profile file. Sometimes, it is also appropriate to include it in your .bashrc file.
export set JAVA_HOME="/usr/lib/jvm/java-17-openjdk-17.0.5.0.8-2.el9_0.x86_64/bin" |
You should also add it to your $PATH variable in your .bashrc file, like:
export set PATH=$PATH:$JAVA_HOME |
Now, let’s write the basic “Hello World” program in Java:
// Define the Java program. public class HelloWorld { public static void main(String[] args) { System.out.println("Hello World!"); } } |
Compile it with:
javac HelloWorld.java |
Run it with the java command:
java HelloWorld |
It prints:
Hello World! |
Let’s download the MySQL/J Connector from the MySQL website, where we con select the operating system and its version, as shown in the image.
After you download the mysql-connector-j RPM package, you can install it with the following dnf command:
sudo dnf install -y mysql-connector-j-8.0.31-1.el9.noarch.rpm |
The log file for this is:
Display detailed console log →
Last metadata expiration check: 2:02:56 ago on Mon 19 Dec 2022 11:32:48 PM EST. Dependencies resolved. ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: mysql-connector-j noarch 1:8.0.31-1.el9 @commandline 2.3 M Transaction Summary ================================================================================ Install 1 Package Total size: 2.3 M Installed size: 2.7 M Downloading Packages: Running transaction check Transaction check succeeded. Running transaction test Transaction test succeeded. Running transaction Regex version mismatch, expected: 10.40 2022-04-14 actual: 10.37 2021-05-26 Regex version mismatch, expected: 10.40 2022-04-14 actual: 10.37 2021-05-26 Preparing : 1/1 Installing : mysql-connector-j-1:8.0.31-1.el9.noarch 1/1 Verifying : mysql-connector-j-1:8.0.31-1.el9.noarch 1/1 Installed: mysql-connector-j-1:8.0.31-1.el9.noarch Complete! |
You should add the $CLASSPATH to your .bashrc file. Add the following line to your .bashrc file and resource your .bashrc file to test the JDBC driver.
export set CLASSPATH="/usr/share/java/mysql-connector-j.jar:." |
Let’s write a slightly larger Java program that tests connectivity to the MySQL database, like:
// Import classes. import java.sql.*; /* You can't include the following on Linux without raising an exception. */ // import com.mysql.jdbc.Driver; public class MySQLConnector { public MySQLConnector() { /* 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 MySQLDriver. Class.forName ("com.mysql.cj.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("MySQLDriver 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 find MySQL driver class:"); System.out.println(e.getMessage()); } catch (InstantiationException e) { System.err.println ("Cannot instantiate class:"); System.out.println(e.getMessage()); } catch (IllegalAccessException e) { System.err.println ("Illegal access exception:"); 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 MySQLDriver(); } } |
Just a note, there’s a deprecated behavior introduced in MySQL 8.0.24, which produces the following error message when compiled looking for deprecation:
javac -Xlint:deprecation MySQLDriver.java |
It produces the following error message, which I hope to sort and update later in the week:
MySQLDriver.java:30: warning: [deprecation] newInstance() in Class has been deprecated
Class.forName ("com.mysql.cj.jdbc.Driver").newInstance();
^
where T is a type-variable:
T extends Object declared in class Class
1 warning |
The code does compile because the deprecation is only a warning. When you run the program, like:
java MySQLDriver |
It returns, confirming a connection to the MySQL database:
Database connection established MySQLDriver Version [8.0.30] Database connection terminated |
As always, I hope this helps those trying to sort out new behaviors.
Eclipse, Java, MySQL
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
- 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.
- Click the Green Arrow to download the Eclipse software.
- The next dialog gives you an option to open or save the software. Click the Open with radio button to open the archive file.
- This the Linux Archive Manager. Click the Extract button from the menu tab to open the archive file.
- 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.
- 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.
- The branding dialog may display for 30 or more seconds before the Eclipse software application launches.
- The Workspace Launcher opens first on a new installation. You need to designate a starting folder. I’m using
/home/student/workspaceas my Workspace. Click the OK button when you enter a confirmed workspace.
- 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.
- 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.
- 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.
- 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.
- 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.
- Now you should see the full screen view of the Eclipse working environment.
- 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.
- 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.
- The only difference in this copy of the New Java Class dialog is that I’ve entered
HelloWorldas the Java Class’s name. Click the Finish button when you’re done.
- Eclipse should show you the following
HelloWorld.javafile. It’s missing amain()method. Add a static main() method to theHelloWorld.javaclass source file.
- This form shows the changes to the
HelloWorld.javafile. Specifically, it adds the It’s missing amain()method. Add a static main() method to theHelloWorld.javaclass source file.
- 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."); }}
- 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.
- 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.
- Navigate to the Project menu and choose the Properties menu option.
- The Properties menu option opens the Properties for the
mysqlproject on the Order and Export tab. Click the Libraries tab to add an external library.
- In the Libraries tab click the Add Library… button on the right to add an external library.
- 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.jarfile, and you should click on it before clicking on the OK button.
- 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.
- Enter
MysqlConnectoras the name of the new Java class file and click the Finish button to continue.
- Eclipse generates the shell of the
MysqlConnectorclass as shown in the illustration to the left.
- You should replace the
MysqlConnectorclass 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("===================="); } } }
- The Save and Launch dialog informs you are saving a
MysqlConnector.javafile to yourmysqlproject. Click the OK button to continue.
- 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] ====================
- 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.sqlandseed_mysql_store_ri2.sqlfiles.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.
Hiding a Java Source
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.
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