GWT + JPA + Hibernate：无法在客户端序列化分层对象

Question

这是 GWT项目。我做了一个示例来说明我的问题：无法序列化分层对象。 我不知道如何解决这个问题。

我正在使用 Hibernate 4.3.5.Final 我的 GWT版本是2.6.0

应用程序正在连接 MySQL数据库。

项目结构

---

hieararchical类

这是我的家庭班。它包含Person对象列表。 导致问题。

package com.myproject.shared;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
public class Family implements Serializable {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id;

    private String familyName;

    @OneToMany (cascade={CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE/*, CascadeType.ALL*/}/*, orphanRemoval = true*/)
    @JoinColumn (name="fk_family") 
    private List<Person> list=new ArrayList<Person>();

    public Family(){

    }

    public void writeToOutput(){
        System.out.println("The Family: ");
        System.out.println("id: "+getId());
        System.out.println("family name: "+getFamily_name());
        System.out.println();       
        System.out.println("lists size: " + list.size());

        for(int j=0; j<list.size(); j++){
            System.out.println("first name: "+ list.get(j).getFirstName());
        }
        System.out.println();
        System.out.println();
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getFamily_name() {
        return familyName;
    }

    public void setFamily_name(String family_name) {
        this.familyName = family_name;
    }

    public List<Person> getList() {
        return list;
    }

    public void setList(List<Person> list) {
        this.list = list;
    }
}

这是 Person class ：

package com.myproject.shared;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class Person implements Serializable {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id;

    private String firstName;


    public Person(){

    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

}

---

数据库

如果项目尚不存在，项目可以生成数据库模式。这很好。

这就是我的表格的样子：

---

错误

但我无法从数据库中读取对象。

如果我尝试从数据库生成一个对象，我会收到此错误：

Starting Jetty on port 8888
   [WARN] Exception while dispatching incoming RPC call
com.google.gwt.user.client.rpc.SerializationException: Type 'org.hibernate.collection.internal.PersistentBag' 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 = [com.myproject.shared.Person@4a637e58, com.myproject.shared.Person@40dbe769, com.myproject.shared.Person@2535bfc3, com.myproject.shared.Person@6bc0ae4a, com.myproject.shared.Person@36f2b38a]
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:667)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:130)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:153)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:587)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeClass(ServerSerializationStreamWriter.java:757)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:796)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:669)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:130)
    at com.google.gwt.user.client.rpc.core.java.util.Collection_CustomFieldSerializerBase.serialize(Collection_CustomFieldSerializerBase.java:44)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serialize(ArrayList_CustomFieldSerializer.java:39)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:51)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:28)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:788)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:669)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:130)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:153)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:587)
    at com.google.gwt.user.server.rpc.RPC.encodeResponse(RPC.java:605)
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForSuccess(RPC.java:471)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:563)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:265)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:305)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:755)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:848)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:686)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:501)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:428)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
    at org.eclipse.jetty.server.handler.RequestLogHandler.handle(RequestLogHandler.java:68)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
    at org.eclipse.jetty.server.Server.handle(Server.java:370)
    at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:489)
    at org.eclipse.jetty.server.AbstractHttpConnection.content(AbstractHttpConnection.java:960)
    at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.content(AbstractHttpConnection.java:1021)
    at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:865)
    at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:240)
    at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
    at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:668)
    at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
    at java.lang.Thread.run(Unknown Source)
[ERROR] 500 - POST /myproject/greet (127.0.0.1) 57 bytes
   Request headers
      Host: 127.0.0.1:8888
      Connection: keep-alive
      Content-Length: 141
      X-GWT-Module-Base: http://127.0.0.1:8888/myproject/
      X-GWT-Permutation: HostedMode
      Origin: http://127.0.0.1:8888
      User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.124 Safari/537.36
      Content-Type: text/x-gwt-rpc; charset=UTF-8
      Accept: */*
      Referer: http://127.0.0.1:8888/MyProject.html?gwt.codesvr=127.0.0.1:9997
      Accept-Encoding: gzip,deflate
      Accept-Language: hu-HU,hu;q=0.8,en-US;q=0.6,en;q=0.4
   Response headers
      Content-Type: text/plain

---

问题

我如何解决我的问题？ 或者我应该使用其他技术？