Integrating an Applet in a Web Application

An applet is a program written in the Java programming language that can be included in an HTML page, much in the same way an image is included in a page. The application that you build in this tutorial shows you how to build and deploy applets in the IDE.

Note: Though there are no project templates that are specifically designed for creating applets in the IDE, you can easily develop them in a Java project and package them in a web project, as shown in this tutorial.

Contents

Content on this page applies to NetBeans IDE 7.2, 7.3, 7.4 and 8.0

To follow this tutorial, you need the following software and resources.

Software or Resource Version Required
NetBeans IDE 7.2, 7.3, 7.4, 8.0, Java Version
Java Development Kit (JDK) version 7 or 8
GlassFish Server Open Source Edition
or
Tomcat servlet container
3.x or 4.x
 
version 7.x or 8.x

Creating or Importing an Applet Source File

In this section, you create your first applet. Possibly, you already have an applet and, in this case, you can use the instructions below to import it into the IDE.

Create the Java project from scratch or from existing sources

  1. Choose File > New Project (Ctrl-Shift-N). Under Categories, select Java.
  2. Choose one of the following:
    • If you are creating a new applet source file, select Java Class Library under Projects. Click Next.
    • If you want to import an applet source file, select Java Project with Existing Sources. Click Next. Specify the file's location in the Source Packages Folder text box.
  3. Under Project Name, type HelloApplet. Change the Project Location to any folder on your computer.
  4. Click Finish. If you imported an applet source file, run it.

Create the applet source file

  1. Right-click the HelloApplet project and choose Properties to open the Properties window.
  2. Select the desired Source / Binary Format for the project and click OK.

    Note: For example, if you choose JDK 6 the applet might not run on machines that have an older version of the JRE or Java browser plugin.

  3. Right-click the HelloApplet project node in the Projects window and select New > Other (Ctrl-N).
  4. Under Categories, select Java. Under File Types, select Applet.

    Alternatively, if you want to visually design your applet, select Swing GUI Forms > JApplet Form.

    Click Next.

  5. Under Class Name, type MyApplet. Under Package, type org.me.hello.
  6. Click Finish.

    The IDE creates the applet source file in the specified package. The applet source file opens in the Source editor.

  7. Define your applet class by copying and pasting the following code over the existing default code:
         package org.me.hello;
    
         import java.applet.Applet;
         import java.awt.Graphics;
    
         public class MyApplet extends Applet {
             @Override
             public void paint(Graphics g) {
                 g.drawString("Hello applet!", 50, 25);
             }
         }
                        

    Alternatively, if you are designing an Applet Form instead, use the Designing a Swing GUI in NetBeans IDE document to create something like the following:

    Applet Form design

    For detailed information on writing applets, see The JavaTM Tutorial's Applets section.

Running an Applet Source File

The applet that you created can be run from the IDE. This section shows you how to do so.

Build and run the applet source file

Right-click the MyApplet.java file node in the Projects window and choose Run File from the contextual menu. The MyApplet.html launcher file, with the applet embedded, is created in the build folder, which you can see if you switch to the Files window (Ctrl-2):

Files window showing built applet

The applet is launched in the Applet Viewer:

View applet

Applet forms are also displayed in the Applet Viewer:

design

Embedding an Applet in a Web Application

Your applet is complete. Now you need to make it available to the user. To do so, you create a web application, put the applet JAR on its classpath, and then add an applet tag to the web application's HTML file.

Create the web project

  1. Choose File > New Project.
  2. Select Web Application in the Java Web category. Click Next.
  3. Under Project Name, type HelloWebApplet.
  4. Change the Project Location to any folder on your computer. Click Next.
  5. Select the target server. Click Finish.

Add the applet JAR file to the web project

When you want to include an applet JAR file in a web project, you can do so by adding the Java project that contains the JAR file, or by adding the JAR file itself. Although the choice is yours, note that when you add the Java project to the web project, you enable the IDE to build the applet whenever you build the web application. Therefore, when you modify the applet in the Java project, the IDE builds a new version of the applet whenever the web project is built. On the other hand, if the applet JAR file is not in a NetBeans IDE project, the applet source file is not rebuilt when you build the web project.

Note: At this point, if you are using the HelloApplet project in the IDE, there is no HelloApplet.jar file. This is OK. The HelloApplet.jar file will be built when you build the HelloWebApplet project.

  1. In the Projects window, right-click the HelloWebApplet project node and select Properties from the contextual menu.
  2. Select the Packaging category.
  3. Choose one of the following:
    • If the applet is in a Java project click Add Project and locate the folder that contains the Java project. Click Add JAR/Folder.

      Note. IDE projects are marked by the NetBeans IDE project icon.

    • If you are using an applet JAR file that is not in an IDE project click Add File/Folder and locate the folder that contains the JAR file. Click Choose.
  4. Confirm that the JAR that contains the applet source file is listed in the table in the Project Properties window. Click OK.

    By default, the applet JAR file will be copied to the web application's web page library, which is the build/web folder. The build/web folder is the root directory of the application and is displayed as "/" in the Path in WAR column of the table. You can modify the location of the applet in the WAR by typing a new location for the applet in the Path in WAR column.

  5. Click Close to close the Project Properties window.

When you build the HelloWebApplet project by choosing Run > Build Project (HelloWebApplet) from the main IDE's menu, the applet's JAR file is generated in the original HelloApplet project and is packaged in the HelloWebApplet project's WAR file. It is also added to the build/web folder. You can follow this process in the Output window and see the results in the Files window.

Applet jar file in applet and web applications

Create and run the JSP file or HTML file

  1. Choose one of the following:
    • If you want to embed the applet in a JSP file, double-click the default index.jsp file in the Projects window. This file is created by the IDE when you create a web project. It opens in the Source Editor.
    • If you want to embed the applet in an HTML file, right-click the HelloWebApplet project node, and choose New > Other from the contextual menu. Under Categories, select Web. Under File Types, select HTML. Click Next. Give your HTML file a name, select the Web folder for its location, and click Finish.
  2. Embed the applet in the file by adding the following applet tag anywhere between the file's <body></body> tags:

    • In an HTML file: <applet code="org.me.hello.MyApplet" archive="HelloApplet.jar"></applet>
    • In a JSP file: <applet code="org.me.hello.MyApplet" archive="HelloApplet.jar" width="600" height="480"/>

    Notes.

    • For this tutorial you can ignore the hint glyph in the left margin if you are adding the applet code to an HTML file.
    • org.me.hello.MyApplet is the full classname to your applet.
    • HelloApplet.jar is the JAR file that contains the applet.
  3. Right-click the JSP node or HTML node in the Projects window and choose Run File from the contextual menu.

    The server deploys the JSP file or HTML file in the IDE's default browser.

    You should see something similar to the illustration below (after you allow to run the application by clicking Run in the Security Warning dialog box):

    View applet

    For applet forms, you should see something similar to the following:

    design



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