Avoiding Resource Caching

A Java plugin installed in a web browser caches access to all HTTP resources that the applet uses. This is useful to avoid downloading all the libraries each time the applet is run. However, this may have undesired side-effects when the applet presents resources loaded via HTTP. If such a resource is modified on the server and the browser window is refreshed, you might end-up with the old content of the resource presented in the applet.

To avoid such a behavior, you need to edit the ro.sync.ecss.samples.AuthorComponentSampleApplet class and set a custom URLStreamHandlerFactory implementation. A sample usage is already available in the class, but it is commented-out for increased flexibility:

//THIS IS HOW YOU CAN REGISTER YOUR OWN PROTOCOL HANDLER TO THE JVM.
//THEN YOU CAN OPEN YOUR CUSTOM URLs IN THE APPLET AND IT WILL USE YOUR HANDLER
URL.setURLStreamHandlerFactory(new URLStreamHandlerFactory() {
	public URLStreamHandler createURLStreamHandler(String protocol) {
		if("http".equals(protocol) || "https".equals(protocol)) {
			return new URLStreamHandler() {
				@Override
				protected URLConnection openConnection(URL u) throws IOException {
					URLConnection connection = new HttpURLConnection(u, null);
					if(!u.toString().endsWith(".jar")) {
						//Do not cache HTTP resources other than JARS
						//By default the Java HTTP connection caches content for 
						//all URLs so if one URL is modified and then re-loaded in the
						//applet the applet will show the old content.
						connection.setDefaultUseCaches(false);
					}
					return connection;
				}
			};
		}
		return null;
	}
});