Google App Engine GWT日期序列化

Question

當Serialize（java.util）Object中的Date字段可用時，出現以下錯誤。我的GWT版本是2.1.1，APP引擎SDk是1.4.2。

是有人對這個問題有什麼想法嗎？

com.google.gwt.user.client.rpc.SerializationException: java.lang.reflect.InvocationTargetException 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeWithCustomSerializer(ServerSerializationStreamWriter.java:764) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:727) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:616) 
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:152) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:534) 
    at com.google.gwt.user.server.rpc.RPC.encodeResponse(RPC.java:609) 
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForSuccess(RPC.java:467) 
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:564) 
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:207) 
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:243) 
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) 
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:58) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:122) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) 
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) 
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) 
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) 
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) 
    at com.google.apphosting.utils.jetty.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:70) 
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:351) 
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
    at org.mortbay.jetty.Server.handle(Server.java:326) 
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) 
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938) 
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755) 
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212) 
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) 
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409) 
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582) 
Caused by: java.lang.reflect.InvocationTargetException 
    at sun.reflect.GeneratedMethodAccessor93.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) 
    at java.lang.reflect.Method.invoke(Method.java:597) 
    at com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:100) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeWithCustomSerializer(ServerSerializationStreamWriter.java:746) 
    ... 38 more 
Caused by: com.google.gwt.user.client.rpc.SerializationException: Type 'org.datanucleus.sco.simple.Date' was not included in the set of types which can be serialized by this SerializationPolicy or its Class object could not be loaded. For security purposes, this type will not be serialized.: instance = Fri Mar 25 06:30:00 UTC 2011 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:614) 
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:152) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:534) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeClass(ServerSerializationStreamWriter.java:704) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:734) 
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:616) 
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126) 
    at com.google.gwt.user.client.rpc.core.java.util.Collection_CustomFieldSerializerBase.serialize(Collection_CustomFieldSerializerBase.java:45) 
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serialize(ArrayList_CustomFieldSerializer.java:38) 
    ... 43 more 

謝謝。

Answer 1

您需要先將服務器上的JDO對象發送回客戶端，然後才能將其分離。

PersistenceManager pm = PMF.getPM(); 
pm.makePersistent(myObject); 
return pm.detachCopy(myObject); 

Answer 2

來看通過這條線從堆棧跟蹤：

Caused by: com.google.gwt.user.client.rpc.SerializationException: Type 'org.datanucleus.sco.simple.Date' was not included in the set of types which can be serialized by this SerializationPolicy or its Class object could not be loaded. For security purposes, this type will not be serialized.: instance = Fri Mar 25 06:30:00 UTC 2011 

這聽起來像你的IDE擁有進口版本的Date比你預期的一個（這是java.util.Date）等。這一直髮生在我身上。只要改變那個錯誤的進口。

Answer 3

問題是由JDO內容返回許多不必要的數據的Date對象。我有固定它像這樣：

public Date getDate() { 
    if(date!= null){ 
     long timeStamp = date.getTime();   
     return new Date(timeStamp); 
    }   
    return null; 
} 

謝謝