Before you can call Java methods from within your PL/SQL programs, you will need to do the following:
Ensure that the Java option has been installed in your Oracle Database Server.
Build and load your Java classes and code elements.
In some cases, have certain Java-specific permissions granted to your Oracle user account.
On the Oracle server, the Java features may or may not be installed, depending on what version of Oracle you are running and what choices your DBA made during the Oracle installation. You can check whether Java is installed by running this query:
SELECT COUNT(*) FROM all_objects WHERE object_type LIKE 'JAVA%';
If the result is 0, Java is definitely not installed, and you can ask your DBA to run a script called $ORACLE_HOME/javavm/install/initjvm.sql.
As a developer, you will probably want to build and test Java programs on your own workstation, and that requires access to a Java Development Kit (JDK). You have two choices when installing the JDK: you can download it from http://java.sun.com/ yourself; or, if you are using a third-party IDE such as Oracle JDeveloper, you may be able to rely on its bundled JDK. Be warned: you may need to be cautious about matching the exact JDK version number.
When you download Java from the Sun site, you will have to choose from among lots of different acronyms and versions. Personally, I’ve had reasonably good luck with Java 2 Standard Edition (J2SE) using the Core Java package rather ...