go www.facebook.com

create an user account, and try to create a photo album.

try to upload a photo, it will load a java applet for the photo upload.

if you use jdk 6 and a proxy server, the applet will fail to load.

without a proxy server, applet loads fine.

also, when using jdk 6, during applet loading, it will pop up a dialog with exception:

sun.plugin.cache.JarCacheVersionException: Number of attributes specified in 'cache_archive' doesn't match those in 'cache_version'
at sun.plugin.cache.JarCacheUtil.getJarsWithVersion(Unknown Source)
at sun.plugin.AppletViewer.initJarVersionMap(Unknown Source)
at sun.plugin.AppletViewer.createClassLoader(Unknown Source)
at sun.plugin.AppletViewer.appletInit(Unknown Source)
at sun.plugin.viewer.LifeCycleManager.initAppletPanel(Unknown Source)
at sun.plugin.viewer.WNetscapePluginObject$Initer.run(Unknown Source)

the exception is indeed valid. cache_archive only has one jar file; file cache_version contains 2 version string.

in JDK 5, the exception dialog did not pop up because of a bug in the code in JarCacheUtil.java, method getJarsWithVersion:

    if(versionCount != versionCount){
throw new JarCacheVersionException( ResourceHandler.getMessage("cache.version_attrib_error") );
}

obviously the exception will never be thrown. hence there is no error dialog when loading with JDK 5.

we should report the cache_archive and cache_version issue to the website itself.