Introduction to Java Web Start tutorial

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JNLP specification about Web start can be downloaded to the Sun Web site http://java.sun.com/products/javawebstart/download-spec.html.

The following is an example of implementing a Java Web start with the simplest HelloWorld method, and the engineering Webstart directory structure is as follows:

The directory description is as follows:

Images: Store the icon file defined in the *.JNLP file

JAR: Store classes packaged jar file

JNLP: Storing *.JNLP description file

Src:java Source

Web-inf/classes:java the compiled class file

Webatart steps are established as follows:

1. Create a new Helloworld.java file under Webstart/src/jws:

Package JWs;

Import javax.swing.*;

public class HelloWorld {

Private JFrame JFrame;

Private JPanel JPanel;

Private JLabel label;

Public HelloWorld () {

JFrame = new JFrame ("HelloWorld Test Frame");

label = new JLabel ("Hello, world!");

JPanel = new JPanel ();

Jpanel.add (label);

Jframe.add (JPanel);

Jframe.pack ();

Jframe.setsize (400, 150);

Jframe.setlocation (400, 300);

Jframe.setvisible (TRUE);

Jframe.setdefaultcloseoperation (Jframe.exit_on_close);

}

Webstart The main method executed at startup

public static void Main (String args[]) {

New HelloWorld ();

}

}

Note: In the Main method it is entirely possible to write a new HelloWorld (), and only one Test statement is printed in the Main method

System.out.println ("This is test!");

For a simple test, the print results appear in the Step 7java console

2. Compile the Helloworld.java and execute the command in the Web-inf/classes directory:

Jar CVF Helloworld.jar Jws/*.class

After execution, copy the generated Helloworld.jar package to the Webstart/jar/jws directory.

(It's handy to pack in idea with a jar tool plug-in, which can be used in Eclipse Fatjar)

3. Extract the MNIFEST.MF from the Helloworld.jar/meta-inf and change the MNIFEST.MF content:

manifest-version:1.0

CREATED-BY:1.5.0_01 (Sun Microsystems Inc.)

For:

manifest-version:1.0

CREATED-BY:1.5.0_01 (Sun Microsystems Inc.)

Main-class:jws. HelloWorld

Then execute the command in the Web-inf/classes directory:

Jar UMF MANIFEST. MF Helloworld.jar

Update the new MNIFEST.MF into the Helloworld.jar package,

Note: If the <application-desc main-class= "JWs" in step 4 below. HelloWorld "/> Specified Main-class method, this step can be omitted.

4. Create a new HELLOWORLD.JNLP file in the WEBSTART/JNLP directory:

<?xml version= "1.0" encoding= "UTF-8"?>

<!--The CodeBase property indicates the top-level URL for the Search application resource, and the following Icon/jar elements are based on this URL .-->

<JNLP codebase= "Http://127.0.0.1:8081/webstart" >

<information>

<!--start Web start by entering "Javaws" or "Javaws-viewer" on the "Start"-"Run" menu, you will see the Webstart application that the client has installed-->

<!--title: application Title Vendor: Suppliers

The Title/vendor element must be displayed with the "javaws-viewer" command

Open Application Cache Viewer (Java application cache Viewer)-->

<title>HelloWorld</title>

<vendor>lively corporation</vendor>

<description>helloworld Test Example for webstart.</description>

<!--homepage: The URL of the relevant documentation for the application, such as Help file, is only description action-->

<!--icon Specifies that icons are displayed in the application cache viewer.

When you create a new Webstart shortcut to the desktop in the viewer, it also appears as a shortcut icon.

Only gif/jpeg formats are supported and other formats are not valid-->

<icon href= "./images/logo.jpg"/>

<!--Splash mentioned in the Sun's documentation that it would appear in the splash screen at webstart startup, but I didn't observe the--> due to the speed problem.

<icon kind= "Splash" href= "/images/logo.jpg"/>

<!--allow offline booting, you can use the Javaws-offline command-->

<offline-allowed/>

</information>

<resources>

<!--Specify the J2SE version that the client needs to install, with the following specified as 1.5 +,

If the version is 1.4, you will be prompted to update the J2SE version when the JNLP file is linked-->

<j2se version= "1.5+"/>

<!--Specify the jar file to download to the local (note that all files need to be packaged before they can be downloaded).

Can contain resource files, such as icons/configuration files, which can be obtained using the GetResource method-->

<jar href= "./jar/jws/helloworld.jar"/>

</resources>

<!--Application-desc must specify which class to execute in the jar file when Webstart starts-->

<application-desc main-class= "JWs. HelloWorld "/>

</jnlp>

Note:

Details of the syntax of the *.JNLP file can be queried on the Sun Web site http://java.sun.com/j2se/1.5.0/docs/guide/javaws/developersguide/syntax.html

The detailed parameters of the Javaws command line can be queried on the Sun Web site http://java.sun.com/j2se/1.5.0/docs/guide/javaws/developersguide/javaws.html#options