Java applet调用WCF服务失败，运行时出现noclassdef异常

Question

我有一个java applet，它使用WCF服务的代理服务来显示数据。applet在Eclipse中可以完美地编译和运行，但当我构建并导出Jar文件并在html页面中运行时，出现

错误

java.lang.NoClassDefFoundError: javax/xml/rpc/ServiceException.

我已经在我的构建路径中包含了jaxrpc.jar，并且我的jar文件包含了所有必需的类。

堆栈跟踪似乎在抱怨我在applet类中实例化代理服务的那一行。有人知道从java applet调用WCF服务是否有问题吗?

堆栈跟踪:

java.lang.RuntimeException: java.lang.NoClassDefFoundError: javax/xml/rpc/ServiceException
at com.sun.deploy.uitoolkit.impl.awt.AWTAppletAdapter.instantiateApplet(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)
Caused by: java.lang.NoClassDefFoundError: javax/xml/rpc/ServiceException
at ListProducts.ListProducts.<init>(ListProducts.java:25)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.sun.deploy.uitoolkit.impl.awt.AWTAppletAdapter$1.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: javax.xml.rpc.ServiceException
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.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 27 more

这件事困扰了我一整天。

Answer 1

我认为你的问题是加载rpc jar，而不是调用wcf。

这篇文章可能会有所帮助:http://www.coderanch.com/t/259357/Applets/java/Applet-Axis-Client-Errors

它建议签名你的jar，验证你可以通过浏览器访问所有的jar，确保你有所有依赖的jar .

如果这一切都没有帮助-我会试着解决它为"NoClassDefFoundError from spplet" issue.

Answer 2

好的。我做了几件事使它工作:

首先，我必须签署几个我正在使用的jar文件:

jaxrpc.jar

axis.jar

commons-discovery-0.2.jar

但不是:

javax.wsdl_1.6.2.v201012040545.jar

org.apache.commons.logging_1.0.4.v201101211617.jar

其次，所有这些文件必须存在于与html页面相同的目录中，因为我没有在codebase属性中为applet标签指定目录。

第三，在我的主applet (ListProducts.class)中，我必须在第一次调用代理服务的代码周围使用AccessController.doPrivileged():编辑:这一步可能不是必要的，因为它现在似乎工作时，我删除doPrivileged块。

AccessController.doPrivileged(new PrivilegedAction() {
        public Object run() {
    try {
        //instantiate proxy service and make rpc's
        //do other stuff with results...

    } catch (RemoteException e) {
        // catch error
    }           

        return null;
        }
    });

这些东西的组合使java applet做它应该做的事情。发现丢失了哪些jar文件，然后对相应的文件进行签名，这是一个痛苦而缓慢的过程。