GWT序列化异常

我有一个返回ArrayList的简单服务方法.但是,当我调用此方法时,我得到如下异常：

com.google.gwt.user.client.rpc.IncompatibleRemoteServiceException: The response could not be deserialized
    at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:221)
    at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:287)
    at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:395)
    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:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:167)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:326)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:207)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:132)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:214)
    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:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:167)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:281)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:531)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:352)
    at java.lang.Thread.run(Thread.java:662)
Caused by: com.google.gwt.user.client.rpc.SerializationException: java.util.ArrayList/3821976829
    at com.google.gwt.user.client.rpc.impl.SerializerBase.getTypeHandler(SerializerBase.java:153)
    at com.google.gwt.user.client.rpc.impl.SerializerBase.instantiate(SerializerBase.java:114)
    at com.google.gwt.user.client.rpc.impl.ClientSerializationStreamReader.deserialize(ClientSerializationStreamReader.java:111)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamReader.readObject(AbstractSerializationStreamReader.java:119)
    at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter$ResponseReader$8.read(RequestCallbackAdapter.java:106)
    at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:214)
    ... 28 more

我使用的是Maven2,GWT 2.3和JavaSE1.6

我知道GWT可以序列化ArrayList,因为我已经无数次地使用它,所以我无法弄清楚这里的世界出了什么问题.

您是否忘记在web.xml中添加servlet和servlet-mapping条目或在服务接口上添加@RemoteServiceRelativePath注释？