GWT：RPC 失败（StatusCodeException）

Question

在我的项目中，实现了 RPC 接口以在 GWT 和服务器之间进行通信，如下所述：

http://code.google.com/webtoolkit/doc/1.6/DevGuideServerCommunication.html

所有现有方法都可以正常调用，但最近我引入了一种新方法，调用它时会导致RPC 失败：（

com.google.gwt.user.client.rpc.StatusCodeException: The call failed on the server; see server log for details
    at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:192)
    at com.google.gwt.http.client.Request.fireOnResponseReceivedImpl(Request.java:254)
    at com.google.gwt.http.client.Request.fireOnResponseReceivedAndCatch(Request.java:226)
    at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:217)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:592)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.moz.MethodDispatch.invoke(MethodDispatch.java:80)
    at org.eclipse.swt.internal.gtk.OS._g_main_context_iteration(Native Method)
    at org.eclipse.swt.internal.gtk.OS.g_main_context_iteration(OS.java:1428)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2840)
    at com.google.gwt.dev.GWTShell.pumpEventLoop(GWTShell.java:720)
    at com.google.gwt.dev.GWTShell.run(GWTShell.java:593)
    at com.google.gwt.dev.GWTShell.main(GWTShell.java:357)

在托管模式下运行时会显示此异常堆栈跟踪）。

以下是我所做的更改：

1. 我使用新方法扩展了我的服务接口：

   @RemoteServiceRelativePath("myservice") 公共接口 MyService 扩展 RemoteService { // ... Boolean isSomethingValid(String paramToCheck); 我

2. 我实现了我的方法：

   公共类 PMyServiceImpl 扩展 GWTSpringController 实现 MyService { // ...

   public Boolean isSomethingValid(String paramToCheck) {
     // 做某事...
   }
   

   }

3. 我将方法定义添加到异步接口中：

   公共接口MyServiceAsync { // ... void isSomethingValid(String paramToCheck, AsyncCallback 回调); }

就是这样。我错过了什么吗？有什么提示说明 RPC 失败的原因吗？在我的服务器日志中，我可以看到以下异常：

[7/26/11 11:48:16:618 CEST] 0000004a WebApp        A   SRVE0181I: [myapplication.war] [/istoolset] [Servlet.LOG]: Exception while dispatching incoming RPC call: com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract java.lang.Boolean com.ubs.istoolset.front.fet.gwt.businessmodel.client.service.MyService.isSomethingValid(java.lang.String)' threw an unexpected exception: java.lang.NullPointerException
        at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:360)
        at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:546)
        at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:164)
        at com.google.gwt.user.server.rpc.RemoteServiceServlet.doPost(RemoteServiceServlet.java:86)
        at com.ubs.istoolset.gwt.framework.rpc.GWTSpringController.handleRequest(GWTSpringController.java:48)
        at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:48)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:859)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:793)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:476)
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:441)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
        at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1146)
        at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:593)
        at com.ibm.ws.wswebcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:534)
        at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:90)
        at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:764)
        at com.ibm.ws.wswebcontainer.WebContainer.handleRequest(WebContainer.java:1478)
        at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:133)
        at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:450)
        at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:508)
        at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:296)
        at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:270)
        at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214)
        at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113)
        at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
        at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
        at com.ibm.io.async.AsyncChannelFuture$1.run(AsyncChannelFuture.java:205)
        at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1497)
Caused by: java.lang.NullPointerException
        at com.ubs.istoolset.front.fet.gwt.businessmodel.server.MyServiceImpl.isSomethingValid(MyServiceImpl.java:1906)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:79)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:618)
        at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:527)
        ... 27 more

非常感谢任何帮助，谢谢！

Answer 1

我不熟悉 com.ubs 命名空间（这是你的代码吗？），但是堆栈跟踪（服务器端）中的 NullPointerException 是一个问题：

Caused by: java.lang.NullPointerException
        at     com.ubs.istoolset.front.fet.gwt.businessmodel.server.MyServiceImpl.isSomethingValid(MyServiceImpl.java:1906)

那里发生了什么？