A Java Web Start application can display a customized loading progress indicator that shows the progress of download of the application's resources.
Consider the Weather application and the CustomProgress
class to understand how to implement a customized loading progress indicator for a Java Web Start application. For the purpose of demonstrating a large and prolonged download, this Java Web Start application's JAR file has been artifically inflated and the customprogress-webstart.jnlp
file specifies additional JAR files as resources.
To develop a customized loading progress indicator for your Java Web Start application, create a class that implements the
DownloadServiceListener
interface.
The constructor of the loading progress indicator class should not have any parameters.
import javax.jnlp.DownloadServiceListener; import java.awt.Container; import java.applet.AppletStub; import netscape.javascript.*; ... public class CustomProgress implements DownloadServiceListener { JFrame frame = null; JProgressBar progressBar = null; boolean uiCreated = false; public CustomProgress() { } ... }
The following code snippet shows how to build the UI for the loading progress indicator:
private void create() { JPanel top = createComponents(); frame = new JFrame(); // top level custom progress indicator UI frame.getContentPane().add(top, BorderLayout.CENTER); frame.setBounds(300,300,400,300); frame.pack(); updateProgressUI(0); } private JPanel createComponents() { JPanel top = new JPanel(); top.setBackground(Color.WHITE); top.setLayout(new BorderLayout(20, 20)); String lblText = "<html><font color=green size=+2>JDK Documentation</font>" + "<br/> The one-stop shop for Java enlightenment! <br/></html>"; JLabel lbl = new JLabel(lblText); top.add(lbl, BorderLayout.NORTH); ... progressBar = new JProgressBar(0, 100); progressBar.setValue(0); progressBar.setStringPainted(true); top.add(progressBar, BorderLayout.SOUTH); return top; }
Create and update the loading progress indicator in the following methods based on the overallPercent
argument. These methods are invoked regularly by the Java Web Start software to communicate the progress of the application's download. Java Web Start software will always send a message when download and validation of resources is 100% complete.
public void progress(URL url, String version, long readSoFar, long total, int overallPercent) { updateProgressUI(overallPercent); } public void upgradingArchive(java.net.URL url, java.lang.String version, int patchPercent, int overallPercent) { updateProgressUI(overallPercent); } public void validating(java.net.URL url, java.lang.String version, long entry, long total, int overallPercent) { updateProgressUI(overallPercent); } private void updateProgressUI(int overallPercent) { if (overallPercent > 0 && overallPercent < 99) { if (!uiCreated) { uiCreated = true; // create custom progress indicator's UI only if // there is more work to do, meaning overallPercent > 0 and < 100 // this prevents flashing when RIA is loaded from cache create(); } progressBar.setValue(overallPercent); SwingUtilities.invokeLater(new Runnable() { public void run() { frame.setVisible(true); } }); } else { // hide frame when overallPercent is above 99 SwingUtilities.invokeLater(new Runnable() { public void run() { frame.setVisible(false); frame.dispose(); } }); } }
Compile the loading progress indicator class and build a JAR file with all the resources needed to display the loading progress indicator. Include the <your JRE directory>/lib/javaws.jar
file in your classpath
to enable compilation.
The loading progress indicator class is now ready for use. The next step is to specify this loading progress indicator JAR file as your Java Web Start application's progress indicator.
To specify a customized loading progress indicator for a Java Web Start application, include the following information in the application's JNLP file:
jar
tag with the download="progress"
attributeprogress-class
attribute with the fully qualified name of the customized loading progress class.The following code snippet from the
file displays the usage of the customprogress-webstart.jnlp
download="progress"
and progress-class
attributes.
<jnlp spec="1.0+" codebase="http://docs.oracle.com/javase/tutorialJWS/deployment/webstart/ex6" href="webstart_AppWithCustomProgressIndicator/customprogress-webstart.jnlp"> ... <resources> <j2se version="1.6+"/> <jar href="webstart_AppWithCustomProgressIndicator/webstart_AppWithCustomProgressIndicator.jar" /> <jar href="webstart_CustomProgressIndicator/webstart_CustomProgressIndicator.jar" download="progress" /> <jar href="webstart_AppWithCustomProgressIndicator/lib/IconDemo.jar" /> <jar href="webstart_AppWithCustomProgressIndicator/lib/SplitPaneDemo.jar" /> <jar href="webstart_AppWithCustomProgressIndicator/lib/SplitPaneDemo2.jar" /> <jar href="webstart_AppWithCustomProgressIndicator/lib/TextBatchPrintingDemo.jar" /> <jar href="webstart_AppWithCustomProgressIndicator/lib/ToolBarDemo.jar" /> <jar href="webstart_AppWithCustomProgressIndicator/lib/ToolBarDemo2.jar" /> <jar href="webstart_AppWithCustomProgressIndicator/lib/SwingSet2.jar" /> </resources> <application-desc main-class="customprogressindicatordemo.Main" progress-class="customprogressindicator.CustomProgress" /> ... </jnlp>
Deploy the Java Web Start application in a web page. Open
in a web browser to view the customized loading progress indicator for the Weather application.JavaWebStartAppPage.html
To view the example properly, you need to install at least the Java SE Development Kit (JDK) 6 update 18 release.
If you have viewed this Java Web Start application before, clear your cache by using the Java Control Panel before viewing the application again. You will not be able to see a progress indicator for a previously cached application.
If you don't see the example running, you might need to enable the JavaScript interpreter in your browser so that the Deployment Toolkit script can function properly.
Download source code for the Java Web Start Application With Customized Loading Progress Indicator example to experiment further.
See the Customizing the Loading Experience topic for more information about customizing the rich Internet application (RIA) loading experience.