Oracle Portal Developer Kit
Developing Portlets Using Java Stored Procedures

You can deploy stored procedures written in Java on an Oracle database. The Java stored procedures are executed as if they are PL/SQL stored procedures.

This article explains how to build portlets which use Java stored procedures. This technique allows developers to take advantage of both the PL/SQL and Java language and is particularly useful if you want to:

CREATING A PORTLET

It is important to remember that the framework language for developing the portlet is still PL/SQL. However, the logic behind the framework can be moved to Java stored procedures. The Java stored procedures are then wrapped by PL/SQL functions in the portlet body.

Hello World Sample (using Java stored procedures)

Let us consider a 'Hello World'  portlet that displays the corresponding mode name whenever a SHOW mode is selected, i.e. SHOW, SHOW_EDIT, SHOW_EDIT_DEFAULTS, SHOW_PREVIEW, SHOW_DETAILS, SHOW_HELP and SHOW_ABOUT. Each mode renders content by calling the corresponding method in a Java class residing in the database. The Java file containing methods corresponding to all the SHOW modes is shown below.

Note: Java class methods which are to be called by PL/SQL procedures/functions should always be static.

HelloWorldJava.java
 

class HelloWorldJava
{
    public static String aboutMode()
    {
        return new String("<b>MODE Show About.<br>Hello World From Java Stored Procedure.</b>");
    }
    public static String editMode()
    {
        return new String("<b>MODE Show Edit.<br>Hello World from Java Stored Procedure.</b>");
    }
    public static String helpMode()
    {
        return new String("<b>MODE Show Help.<br>Hello World From Java Stored Procedure.</b>");
    }
    public static String editDefaultsMode()
    {
        return new String("<b>MODE Show Edit Defaults.<br>Hello World From Java Stored Procedure.</b>");
    }
    public static String showMode()
    {
        return new String("<b>MODE Show.<br>Hello World From Java Stored Procedure.</b>");
    }
    public static String detailsMode()
    {
        return new String("<b>MODE Show Details.<br>Hello World From Java Stored Procedure.</b>");
    }
    public static String previewMode()
    {
        return new String("<b>MODE Show Preview.<br>Hello World From Java Stored Procedure.</b>");
    }
}

  1. Compile the Java class file HelloWorldJava.java.

  2. Ensure that the ORACLE_HOME environment variable is set.

  3. Deploy the compiled class file HelloWorldJava.class in the database.

From the directory where HelloWorldJava.class resides, execute the command outlined below:

C:\%ORACLE_HOME%\bin\loadjava  -v -resolve -user %provider_schemaa%/%provider_password%@%connect_string% HelloWorldJava.class

  1. Once the class file is deployed, you can call methods inside the Java class.

    For example:

    function get_preview_mode_content
        return varchar2
        as
        language java name 'HelloWorldJava.previewMode() return oracle.sql.CHAR';

The PL/SQL procedures/functions that invoke methods in the Java class are called from the PL/SQL show() procedure (see below). When they call their corresponding Java methods, they receive the java.lang.String object as oracle.sql.CHAR. This in turn is passed to the show() procedure.

procedure show
(
    p_portlet_record        wwpro_api_provider.portlet_runtime_record
)
is
...
...
    l_edit varchar2(1000);
    l_help varchar2(1000);
    l_about varchar2(1000);
    l_edit_defaults varchar2(1000);
    l_show varchar2(1000);
    l_details varchar2(1000);
    l_preview varchar2(1000);
begin
...
...
        if (p_portlet_record.exec_mode = wwpro_api_provider.MODE_SHOW) then
            if (p_portlet_record.has_title_region) then
                wwui_api_portlet.draw_portlet_header
                (
                     p_provider_id       => p_portlet_record.provider_id
                    ,p_portlet_id        => p_portlet_record.portlet_id
                    ,p_title             => l_portlet.title
                    ,p_has_details       => true
                    ,p_has_edit          => true
                    ,p_has_help          => true
                    ,p_has_about         => true
                    ,p_referencepath     => p_portlet_record.reference_path
                    ,p_back_url          => p_portlet_record.page_url
                );
            end if;
            wwui_api_portlet.open_portlet(p_portlet_record.has_border);
      /*
           Calls get_show_mode_content function - display the content of the portlet in the show mode.
             */
            l_show := get_show_mode_content();
            htp.p(l_show);

            if (p_portlet_record.has_border) then
                wwui_api_portlet.close_portlet;
            end if;
        elsif (p_portlet_record.exec_mode = wwpro_api_provider.MODE_SHOW_ABOUT) then
      /*
            Calls get_about_mode_content function - display the about page for the portlet.
            */
            l_about := get_about_mode_content();
            htp.p(l_about);
            ...
           ...
/*
Code for other modes goes here. 
*/
...
...
    end show;

/*
    Functions that call the Java Methods
*/

    function get_show_mode_content
    return varchar2
    as
    language java name 'HelloWorldJava.showMode() return oracle.sql.CHAR';

    function get_about_mode_content
    return varchar2
    as
    language java name 'HelloWorldJava.aboutMode() return oracle.sql.CHAR';
    ...
    ...
/*
    Calls made here for other modes
*/

 

The functions that call the Java methods should be declared in the package specification (.pks) file. Here, the show() functionality is transferred from the PL/SQL procedure to the Java class. This can be extended to any procedure inside a PL/SQL package.

This example is a primer describing how to use Java code while developing PL/SQL portlets. You can use a similar approach when creating other PL/SQL portlets that utilize Java code.

Installing Hello World Sample

Installable source code for the above example can be downloaded from here.

The instructions for installing the sample are available here.

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