Question

从头开始一个新项目，转换为JPA，我的持久性提供程序是EclipseLink，添加了必要的库（eclipselink.jar，eclipselink.jar，javax.persistence，mysql-connector-java-5.1）。测试连接，ping ok。然后创建了一个新包＆gt; JPA＆gt;来自表格的实体＆gt;选择所有实体和密钥生成器＆gt;身份。

GestorIpca.java

            GestorIpcaService.util.getInstance().getLista(new AsyncCallback<ArrayList<Docente>>() {

                @Override
                public void onFailure(Throwable caught) {
                    Window.alert("Erro na Ligacao efectuada");
                    caught.getStackTrace();
                }

                @Override
                public void onSuccess(ArrayList<Docente> result) {
                    Window.alert("Ligacao efectuada com sucesso:" + result.size());
                }
            });

GestorIpcaService

@RemoteServiceRelativePath("greet")
public interface GestorIpcaService extends RemoteService {
    String greetServer(String name) throws IllegalArgumentException;

    public static class util{
        public static GestorIpcaServiceAsync instance;
        public static GestorIpcaServiceAsync getInstance(){
            if(instance == null){
                instance = GWT.create(GestorIpcaService.class);
            }
        return instance;
        }
    }
    public ArrayList<Docente> getLista() throws IllegalArgumentException;
}

GestorIpcaServiceAsync

public interface GestorIpcaServiceAsync {
        void greetServer(String input, AsyncCallback<String> callback)
                throws IllegalArgumentException;

        void getLista(AsyncCallback<ArrayList<Docente>> callback);
    }

GestorIpcaServiceImpl

@SuppressWarnings("serial")
public class GestorIpcaServiceImpl extends RemoteServiceServlet implements
        GestorIpcaService {

    public ArrayList<Docente> getLista() throws IllegalArgumentException  {
        //Criamos um EntityManager
        EntityManager em = JpaUtil.getEntityManagerFactory().createEntityManager();
        //Criamos a consulta
        String consulta = "SELECT r from Docente r";
        //Executamos a consulta
        Query q = em.createQuery(consulta);
        ArrayList<Docente> lista = new ArrayList<Docente>(q.getResultList());
        return lista;
    }
/*  public static void main(String args[]){
        GestorIpcaServiceImpl serviceImpl = new GestorIpcaServiceImpl();
        for (Docente docente : serviceImpl.getLista()){
            System.out.println("nome: " + docente.getNome());
        }
    }
    */

在此文件中，我尝试以＆gt;运行Java Application和Console中显示了2条记录。 包com.GestorIpca.factory

import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

public class JpaUtil {
    private static final EntityManagerFactory emf;
    //Método estático
    static{
        //BLoco try
        try
        {
            //Criação de EntityManagerFactory
            emf = Persistence.createEntityManagerFactory("GestorIpca");
        }catch (Throwable e){
            //Controlar as excepções
            System.err.println("A criação de SessionFactory falhou" + e);
            e.printStackTrace();
            throw new ExceptionInInitializerError(e);
        }
    }

    public static EntityManagerFactory getEntityManagerFactory(){
        return emf;
    }
}

我的 persistence.xml 是自动创建的。放在META-INF内部

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
    <persistence-unit name="GestorIpca">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>

    <class>com.GestorIpca.shared.Ano</class>
    <class>com.GestorIpca.shared.Categoria</class>
    <class>com.GestorIpca.shared.Curso</class>
    <class>com.GestorIpca.shared.Disciplina</class>
    <class>com.GestorIpca.shared.Disponibilidade</class>
    <class>com.GestorIpca.shared.Docente</class>
    <class>com.GestorIpca.shared.Sala</class>
    <class>com.GestorIpca.shared.Semestre</class>
    <class>com.GestorIpca.shared.TipoCurso</class>
    <class>com.GestorIpca.shared.Turma</class>
    <class>com.GestorIpca.shared.User</class>
        <properties>
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/timetable"/>
            <property name="javax.persistence.jdbc.user" value="root"/>
            <property name="javax.persistence.jdbc.password" value="k771u3"/>
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
        </properties>
    </persistence-unit>
</persistence>

最后一步＆gt;以＆gt;运行Web应用程序错误＆gt;无法连接到数据库并在Eclipse控制台中打印堆栈跟踪

[EL Info]: 2011-05-09 10:03:08.78--ServerSession(8068087)--EclipseLink, version: Eclipse Persistence Services - 2.2.0.v20110202-r8913
[EL Info]: 2011-05-09 10:03:09.297--ServerSession(8068087)--file:/C:/Users/Martinho/WorkSpace/GestorIpca/war/WEB-INF/classes/_GestorIpca login successful
Starting Jetty on port 8888
   [WARN] Exception while dispatching incoming RPC call
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$8.write(ServerSerializationStreamWriter.java:152)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:534)
    at com.google.gwt.user.server.rpc.RPC.encodeResponse(RPC.java:616)
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForSuccess(RPC.java:474)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:571)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:324)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
    at org.mortbay.jetty.HttpConnection$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$PoolThread.run(QueuedThreadPool.java:488)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeWithCustomSerializer(ServerSerializationStreamWriter.java:746)
    ... 30 more
Caused by: com.google.gwt.user.client.rpc.SerializationException: Type 'org.eclipse.persistence.indirection.IndirectSet' was not included in the set of types which can be serialized by this SerializationPolicy or its Class object could not be loaded. For security purposes, this type will not be serialized.: instance = {IndirectSet: not instantiated}
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:614)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:152)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:534)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeClass(ServerSerializationStreamWriter.java:704)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:734)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:616)
    at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:126)
    at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$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)
    ... 35 more
[ERROR] 500 - POST /gestoripca/greet (127.0.0.1) 57 bytes
   Request headers
      Host: 127.0.0.1:8888
      Connection: keep-alive
      Referer: http://127.0.0.1:8888/GestorIpca.html?gwt.codesvr=127.0.0.1:9997
      Content-Length: 132
      Origin: http://127.0.0.1:8888
      X-GWT-Module-Base: http://127.0.0.1:8888/gestoripca/
      X-GWT-Permutation: HostedMode
      User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.30 Safari/534.30
      Content-Type: text/x-gwt-rpc; charset=UTF-8
      Accept: */*
      Accept-Encoding: gzip,deflate,sdch
      Accept-Language: pt-PT,pt;q=0.8,en-US;q=0.6,en;q=0.4
      Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
   Response headers
      Content-Type: text/plain

注意：我在com.GestorIpca.shared包中更改了从表中生成的所有类

public class Ano implements Serializable

到

public class Ano implements IsSerializable

也改变了我的 GestorIpca.gwt.xml 并在最后添加了这些行

<extend-configuration-property name="rpc.blacklist" value="com.google.gwt.user.client.ui.*Collection"/>
<extend-configuration-property name="rpc.blacklist" value="-.*List"/>
<extend-configuration-property name="rpc.blacklist" value="-.*Map"/>
<extend-configuration-property name="rpc.blacklist" value="-.*Collection"/>
<extend-configuration-property name="rpc.blacklist" value="+java.util.HashMap"/>
<extend-configuration-property name="rpc.blacklist" value="+java.util.LinkedHashMap"/>
<extend-configuration-property name="rpc.blacklist" value="+java.util.ArrayList"/>

我缺少什么？

Answer 1

我取决于你的实体是如何定义的。也许有GWT RPC不喜欢的连接。在这种情况下，我建议创建DTO或实现RequestFactory

Answer 2

在不知道您的实体是什么样子的情况下，我会从异常中猜测，原因可能是您的实体如何通过持久性提供程序得到增强：

对于GWT RPC来说，这意味着当对象准备通过线路传输时，它实际上与编译器认为将要传输的对象不同，因此在尝试反序列化时， GWT RPC机制不再知道类型是什么，并拒绝反序列化它。

引自：http://code.google.com/intl/de-DE/webtoolkit/articles/using_gwt_with_hibernate.html

该文章还建议如何创建DTO来解决这个问题。

Answer 3

我知道这是一个非常古老的问题，但今晚我遇到了这个问题。

GWT序列化似乎不像java.util.Set。我几乎觉得java.util.Set与org.eclipse.persistence.indirection.IndirectSet混淆了。

一旦我将Set切换到ArrayList，错误就消失了。

GWT RCP - SerializationException

3 个答案: