|
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" attribute progress-class attribute with the fully qualified name of the
customized loading progress class.
customprogress-webstart.jnlpdownload="progress" and
progress-class attributes.
<jnlp spec="1.0+" codebase="http://download.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
JavaWebStartAppPage.html
See the Customizing the Loading Experience topic for more information about customizing the rich Internet application (RIA) loading experience.
|
