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I am using an applet that will be called by JavaScript in the background to access the clipboard and copy the contents. I am using the below code to load the applet in my JSP file. 

var attributes = { id:'applet', code:'com.applet.Applet.class', archive:'/applet/applet.jar', width:1, height:1, style:'display:none' } ; 
var parameters = { } ;
deployJava.runApplet(attributes, parameters, '1.4');

The applet is signed, loads and runs fine 99% of the time. But, sporadically I see errors stating that few runtime JAVA classes are not found which I don't use. Its purely runtime classes which is required to load the applet itself. Also, it does not fail for the same class. It fails for different classes. Is there something that I am missing?

Unfortunately, this happens only in higher environments where we don't have much control to enable the trace and logs.

Let me know if any additional information is required.

Example: 

java.lang.NoClassDefFoundError: Could not initialize class sun.net.www.http.KeepAliveStream
    at sun.net.www.http.HttpClient.parseHTTPHeader(Unknown Source)
    at sun.net.www.http.HttpClient.parseHTTP(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source)
    at sun.plugin.PluginURLJarFileCallBack.downloadJAR(Unknown Source)
    at sun.plugin.PluginURLJarFileCallBack.access$000(Unknown Source)
    at sun.plugin.PluginURLJarFileCallBack$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.plugin.PluginURLJarFileCallBack.retrieve(Unknown Source)
    at sun.net.www.protocol.jar.URLJarFile.retrieve(Unknown Source)
    at sun.net.www.protocol.jar.URLJarFile.getJarFile(Unknown Source)
    at sun.net.www.protocol.jar.JarFileFactory.get(Unknown Source)
    at sun.net.www.protocol.jar.JarURLConnection.connect(Unknown Source)
    at sun.plugin.net.protocol.jar.CachedJarURLConnection.connect(Unknown Source)
    at sun.plugin.net.protocol.jar.CachedJarURLConnection.getJarFileInternal(Unknown Source)
    at sun.plugin.net.protocol.jar.CachedJarURLConnection.getJarFile(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader.getJarFile(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader.access$1000(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader.ensureOpen(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$JarLoader.<init>(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
    at com.sun.deploy.security.DeployURLClassPath.getResource(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(Unknown Source)
    at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager.initAppletAdapter(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Andrew Thompson
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Viswanathan Gurumurthy
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  • Looks like there is something wrong with the response your webserver gives when you're trying to donwload the JAR file. Or something (a proxy) could be messing things up, or it could be a network error between the server and client. Since it works 99% of the time, it is very difficult to diagnose this just by looking at the error. – biziclop Aug 06 '15 at 17:18
  • By the way, this error (despite its name) in this case doesn't mean the class isn't found, it means that something has gone wrong while loading the applet, when trying to parse the HTTP response of the server. – biziclop Aug 06 '15 at 17:21

0 Answers0