Question

我是GAE，GWT，Hibernate和JDO的新手。我有Bus，BusStop和Route类，序列化如下：

BaseObject.java

package org.symphony.suchitra.gae.client.admin.model;
import java.io.Serializable;
public interface BaseObject extends Serializable {
    String getId();
}

Bus.java

@PersistenceCapable(identityType=IdentityType.APPLICATION)
public class Bus implements BaseObject {
    @PrimaryKey
    @Persistent(valueStrategy =IdGeneratorStrategy.IDENTITY)
    protected Long id;

    public String getId() {
        if( id == null ) {
            return null;
        }

        return id.toString();
    }

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

    @Persistent
    protected String busNumber;
    @Persistent
    @Unique
    protected String busIdentifier;
    @Persistent
    protected String routeId;

    public String getBusNumber() {
        return busNumber;
    }

    public void setBusNumber(String busNumber) {
        this.busNumber = busNumber;
    }

    public String getBusIdentifier() {
        return busIdentifier;
    }

    public void setBusIdentifier(String busIdentifier) {
        this.busIdentifier = busIdentifier;
    }

    public String getRouteId() {
        return routeId;
    }

    public void setRouteId(String routeId) {
        this.routeId = routeId;
    }
}

BusStop.java

@PersistenceCapable(identityType=IdentityType.APPLICATION)

public class BusStop implements BaseObject{
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    protected Long ident;

    public String getId() {
        if( ident == null ) {
            return null;
        }

        return ident.toString();
    }

    public void setId(String id) {
        this.ident = Long.parseLong(id);
    }

    @Persistent
    @Unique
    private String name;
    @Persistent
    private String latitude;
    @Persistent
    private String longitude;

    public String getLatitude() {
        return latitude;
    }

    public void setLatitude(String email) {
        this.latitude = email;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getLongitude() {
        return longitude;
    }

    public void setLongitude(String password) {
        this.longitude = password;
    }
}

Route.java

@PersistenceCapable (identityType=IdentityType.APPLICATION)
public class Route implements BaseObject{
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    protected Long id;

    public String getId() {
        if( id == null ) {
            return null;
        }

        return id.toString();
    }

    public void setId(String id) {
        this.id = Long.parseLong(id);
    }

    @Persistent
    private String name;
    @Persistent
    private String sourceId;
    @Persistent
    private String destinationId;

    public String getSourceId() {
        return sourceId;
    }

    public void setSourceId(String source) {
        this.sourceId = source;
    }

    public String getDestinationId() {
        return destinationId;
    }

    public void setDestinationId(String destinationId) {
        this.destinationId = destinationId;
    }

    @Persistent
    private String totalDistance;
    @Persistent
    private String totalTime;
    @Persistent
    private List<Long> busStopKeys;

    @NotPersistent
    private List<BusStop> busStops;

    public String getTotalTime() {
        return totalTime;
    }

    public void setTotalTime(String totalTime) {
        this.totalTime = totalTime;
    }

    public List<BusStop> getBusStops() {
        return busStops;
    }

    public void setBusStops(List<BusStop> busStops) {
        this.busStops = busStops;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getTotalDistance() {
        return totalDistance;
    }

    public void setTotalDistance(String totalDistance) {
        this.totalDistance = totalDistance;
    }

    public List<Long> getBusStopKeys() {
        return busStopKeys;
    }

    public void setBusStopKeys(List<Long> busStopKeys) {
        this.busStopKeys = busStopKeys;
    }   
}

Hibernate映射：

bus.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping  PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"       "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

 <hibernate-mapping>
<class name="org.symphony.suchitra.gae.client.admin.model.Bus" table="bus">
    <id column="bus_id" name="bus_id" type="java.lang.String"> 
        <generator class="org.hibernate.id.UUIDHexGenerator"> 
        </generator> 
    </id> 
    <property name="bus_number"/> 
    <property name="bus_identifier" unique="true"/>
    <property name="route_id"/>
</class>
 </hibernate-mapping>

busstop.hbm.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE hibernate-mapping  PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
<class name="org.symphony.suchitra.gae.client.admin.model.BusStop" table="busstop">
    <id column="busstop_id" name="busstop_id" type="java.lang.String"> 
        <generator class="org.hibernate.id.UUIDHexGenerator"> 
        </generator> 
    </id> 
    <property name="name"/> 
    <property name="latitude"/> 
    <property name="longitude"/> 
</class>
 </hibernate-mapping>

route.hbm.xml

  <?xml version="1.0" encoding="UTF-8"?>
  <!DOCTYPE hibernate-mapping  PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

  <hibernate-mapping>
<class name="org.symphony.suchitra.gae.client.admin.model.Route">
    <id column="route_id" name="route_id" type="java.lang.String"> 
        <generator class="org.hibernate.id.UUIDHexGenerator"> 
        </generator> 
    </id> 
    <property name="name"/> 
    <property name="source"/>
    <property name="destination"/>
    <property name="total_distance"/> 
    <property name="total_time"/>
    <list name="busstoplist" table="busstoplist" cascade="save-update"> 
        <key column="route_id"/> 
        <list-index column="busstoplist_id"/> 
        <many-to-many class="org.symphony.suchitra.gae.client.admin.model.BusStop"   column="busstop_id"/>
    </list> 
</class>
  </hibernate-mapping>

在这里，路线和公共汽车站有多对多的关系，每辆公共汽车都有一条路线。我只是在总线中存储路由的id，但是在检索总线对象时，它给出了以下错误

com.google.gwt.user.client.rpc.SerializationException：类型'org.datanucleus.sco.backed.ArrayList'未包含在可由此SerializationPolicy序列化的类型集中，或者其Class对象无法加载。出于安全考虑，此类型不会被序列化：实例

存储它时没有问题。现在我没有直接处理Bus对象中的ArrayList。所以我无法弄清楚在哪里操纵datanucleus ArrayList对象 util ArrayList。

此外，当我将busstop id存储在总线表中而不是路由id时，程序运行正常。获取总线对象后，我正在显示其详细信息。在这样做时，我通过RouteDAO检索路由对象的名称字段。

请帮帮我......

Answer 1

解决了..由于将Route对象的busStops和busStopKeys列表从服务器发送到客户端，异常已经上升。在将数据发送到客户端之前设置为null的列表解决了问题。我有另一种方法来检索与路由相关的公交车站列表.. Donno如果它是正确的方式，但它解决了问题..现在将重写代码使其成为一个正确的JDO代码.. Thanx给所有给他们的人是时候建议解决我的问题..

Answer 2

添加

datanucleus-core-1.1.0.jar

到你的类路径。然后再试一次

下载网址： http://www.docjar.com/jar_detail/datanucleus-core-1.1.0.jar.html

Answer 3

我认为你不需要Hibernate。 Datanucleus是GAE使用的数据库提供者，它将与JDO一起工作。

com.google.gwt.user.client.rpc.SerializationException

3 个答案: