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You can set certain Java Virtual Machine arguments and secure properties
for your rich Internet
application (RIA) in the RIA's Java Network Launch Protocol (JNLP) file.
For applets, you can also set arguments in the
java_arguments parameter of the <applet> tag.
Although there is a predefined set of secure properties, you can also define new
secure properties by prefixing the property name with "jnlp."
or "javaws.".
Properties can be retrieved in your RIA by using the System.getProperty
method.
Consider the Properties and Arguments Demo applet.
The following Java Virtual Machine arguments and properties are set in the applet's
JNLP file,
appletpropsargs.jnlp.
-Xmx – A secure argument set equal to "256M"sun.java2d.noddraw – A predefined secure property
set equal to "true"
jnlp.myProperty – A user-defined secure property
set equal to "a user-defined property"
<?xml version="1.0" encoding="UTF-8"?>
<jnlp spec="1.0+" codebase="" href="">
<information>
<title>Properties and Arguments Demo Applet</title>
<vendor>Dynamic Team</vendor>
</information>
<resources>
<!-- Application Resources -->
<j2se version="1.6+"
href="http://java.sun.com/products/autodl/j2se"
java-vm-args="-Xmx256M"/> <!-- secure java vm argument -->
<jar href="applet_PropertiesAndVMArgs.jar" main="true" />
<!-- secure properties -->
<property name="sun.java2d.noddraw" value="true"/>
<property name="jnlp.myProperty" value="a user-defined property"/>
</resources>
<applet-desc
name="Properties and Arguments Demo Applet"
main-class="PropertiesArgsDemoApplet"
width="800"
height="50">
</applet-desc>
<update check="background"/>
</jnlp>
The
PropertiesArgsDemoApplet class uses the System.getProperty method to retrieve the
java.version property and other properties that
are set in the JNLP file. The PropertiesArgsDemoApplet class
also displays the properties.
import javax.swing.JApplet;
import javax.swing.SwingUtilities;
import javax.swing.JLabel;
public class PropertiesArgsDemoApplet extends JApplet {
public void init() {
final String javaVersion = System.getProperty("java.version");
final String swing2dNoDrawProperty = System.getProperty("sun.java2d.noddraw");
final String jnlpMyProperty = System.getProperty("jnlp.myProperty");
try {
SwingUtilities.invokeAndWait(new Runnable() {
public void run() {
createGUI(javaVersion, swing2dNoDrawProperty, jnlpMyProperty);
}
});
} catch (Exception e) {
System.err.println("createGUI didn't successfully complete");
}
}
private void createGUI(String javaVersion, String swing2dNoDrawProperty, String jnlpMyProperty) {
String text = "Properties: java.version = " + javaVersion +
", sun.java2d.noddraw = " + swing2dNoDrawProperty +
", jnlp.myProperty = " + jnlpMyProperty;
JLabel lbl = new JLabel(text);
add(lbl);
}
}
The Properties and Arguments Demo applet is shown next. You can also see the
applet running in
AppletPage.html.
Download source code for the Properties and Arguments Demo Applet example to experiment further.
See System Properties for a complete set of system properties that can be accessed by RIAs.
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