1

我在通过 GWT 中的 RPC 调用传输一个对象时遇到问题。我在这个项目中使用 Spring MVC 和 Hibernate。

这是实体类：

@Entity
public class Room implements Serializable{
    private static final long serialVersionUID = -5924198459524011627L;

    private Long id;
    private String name;
    private String description;

    private Set<Wall> walls = new HashSet<Wall>(0);

    public Room(){
    }

    public Room(String name, String description){
        this.name = name;
        this.description = description;
    }

    public Room(String name, String description, Set<Wall> walls){
        this.name = name;
        this.description = description;
        this.walls = walls;
    }

    @Id
    @Column(name = "ROOM_ID")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }

    @ManyToMany(cascade = CascadeType.ALL, fetch=FetchType.EAGER)
    @JoinTable(name = "ROOM_WALL", joinColumns = {@JoinColumn(name = "ROOM_ID")},
            inverseJoinColumns = {@JoinColumn(name = "WALL_ID")})
    public Set<Wall> getWalls(){
        return walls;
    }   

    public void setWalls(Set<Wall> walls){
        this.walls = walls;
    }
}

这是我的RoomDAO：

@Repository
public class RoomDAO {

    @Autowired
    private HibernateTemplate hibernate;

    public Room get(Long id){
        return hibernate.get(Room.class, id);
    }

    public void delete(Room entity){
        hibernate.delete(entity);
    }

    public void save(Room entity){
        hibernate.saveOrUpdate(entity);
    }

    private Session getCurrentSession(){
        return hibernate.getSessionFactory().getCurrentSession();
    }   

    @SuppressWarnings("unchecked")
    public List<Room> list(){
        String queryStr = "from "+Room.class.getSimpleName()+" fetch all properties";
        Query query = getCurrentSession().createQuery(queryStr);
        System.out.println("Room list succesfull");
        return (List<Room>)query.list();
    }

    @SuppressWarnings("unchecked")
    public List<Wall> getWalls(Long id){
        String queryStr = "from "+Wall.class.getSimpleName()+" wl join wl.walls ls where ls.id=:"+id;
        Query query = getCurrentSession().createQuery(queryStr);
        System.out.println("Walls list succesfull");
        return (List<Wall>)query.list();
    }
}

这是我获得的错误消息：

com.google.gwt.user.client.rpc.SerializationException: Type 'org.hibernate.collection.PersistentSet' 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 = []
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:619)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:153)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:539)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeClass(ServerSerializationStreamWriter.java:709)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:748)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:621)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.client.rpc.core.java.util.Collection_CustomFieldSerializerBase.serialize(Collection_CustomFieldSerializerBase.java:44)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serialize(ArrayList_CustomFieldSerializer.java:39)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:51)
    at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serializeInstance(ArrayList_CustomFieldSerializer.java:28)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:740)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:621)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:153)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:539)
    at com.google.gwt.user.server.rpc.RPC.encodeResponse(RPC.java:616)
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForSuccess(RPC.java:474)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:571)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:551)
    at org.spring4gwt.server.SpringGwtRemoteServiceServlet.processCall(SpringGwtRemoteServiceServlet.java:37)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:324)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)

我想问一下这个问题是否是由ManyToMany关系和Set用于映射我的实体之间的关系引起的。因为当我在使用 Set 的地方传输一个没有任何关系（ManyToMany 或 OneToMany 等）的对象时，RPC 调用工作正常。

是否可以作为 List 替换 Set 的解决方案？我知道 List 对数据库无效，但我不想重建整个项目：D

我发现这些问题可以通过使用 Dozer for ex 来解决。

非常感谢您的回答:)

4

1 回答 1

2

这是一个已知问题。请查看一章使用 GWT 和 Hibernate中的为什么 Hibernate 对象在到达浏览器世界时无法被理解一章。

于 2012-07-27T09:01:53.903 回答