ClassCastException 与 Hibernate ManyToMany 连接查询
ClassCastException with Hibernate ManyToMany Join Query
我有两个实体，奖励和用户，它们相关 manytomany 如下：
public class Reward {
@Id
@Column(name="reward_id")
private long rewardId;
@ManyToMany(mappedBy="favourite")
@LazyCollection(LazyCollectionOption.FALSE)
private Collection<User> favouriteUsers;
}
而用户：
public class User {
@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE)
@Column(name="user_id")
private long userId;
@ManyToMany
@JoinTable(name="FAVOURITE", joinColumns=@JoinColumn(name="user_id"), inverseJoinColumns=@JoinColumn(name="favourite_id"))
@LazyCollection(LazyCollectionOption.FALSE)
private Collection<Reward> favourite = new ArrayList<Reward>();
}
我正在尝试使用以下查询从 FAVOURITE table 检索特定 user_id 和 reward_id 的条目：
@NamedQuery(name="Favourite.byUserAndReward", query="from Reward r join r.favouriteUsers u where u.userId = ? and r.rewardId = ?")
问题是当我 运行 这个查询并将查询结果等同于类型 Reward 时，我得到以下异常：
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.xxxxxxx.model.Reward
at com.xxxxxxx.sevice.RewardService.addFavourite(RewardService.java:26)
at com.xxxxxxx.resources.RewardResource.addFavourite(RewardResource.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory.invoke(ResourceMethodInvocationHandlerFactory.java:81)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.run(AbstractJavaResourceMethodDispatcher.java:144)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:205)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
at org.glassfish.jersey.server.ServerRuntime.run(ServerRuntime.java:326)
at org.glassfish.jersey.internal.Errors.call(Errors.java:271)
at org.glassfish.jersey.internal.Errors.call(Errors.java:267)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
此查询的休眠查询日志如下：
Hibernate: select favouriteu0_.favourite_id as favourit2_3_0_, favouriteu0_.user_id as user_id1_3_0_, user1_.user_id as user_id1_2_1_ from FAVOURITE favouriteu0_ inner join USER user1_ on favouriteu0_.user_id=user1_.user_id where favouriteu0_.favourite_id=?
我想不出错误。有人可以帮忙吗？
编辑：我执行查询的部分是：
public Reward addFavourite(long userId, Reward favouriteReward) {
Object<Reward> rewardObject = new ObjectImpl<Reward>();
long favouriteId = favouriteReward.getRewardId();
// Check if favourited before.
// Below is the line that throws the exception.
Reward checkReward = rewardObject.getObjectByNamedQueryLongLong("Favourite.byUserAndReward", userId, favouriteId)
if (checkReward != null) {
return favouriteReward;
}
}
[Ljava.lang.Object 表示您的查询正在返回 array 个对象，而您正试图将其转换为一个对象。
更新：
由于您在没有 SELECT 子句的情况下进行查询并且还加入了 User、Hibernate returns Reward 和 User 对象，这就是为什么您得到 Object[].我可以想到两个解决方案。
- 您可以在
SELECT 子句中提及您想要获得的对象，例如
select r from Reward r join r.favouriteUsers u where u.userId = ? and r.rewardId = ?
- 或者，您可以在查询中使用
fetch，例如 from Reward r join fetch r.favouriteUsers u where u.userId = ? and r.rewardId = ?
我有两个实体，奖励和用户，它们相关 manytomany 如下：
public class Reward {
@Id
@Column(name="reward_id")
private long rewardId;
@ManyToMany(mappedBy="favourite")
@LazyCollection(LazyCollectionOption.FALSE)
private Collection<User> favouriteUsers;
}
而用户：
public class User {
@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE)
@Column(name="user_id")
private long userId;
@ManyToMany
@JoinTable(name="FAVOURITE", joinColumns=@JoinColumn(name="user_id"), inverseJoinColumns=@JoinColumn(name="favourite_id"))
@LazyCollection(LazyCollectionOption.FALSE)
private Collection<Reward> favourite = new ArrayList<Reward>();
}
我正在尝试使用以下查询从 FAVOURITE table 检索特定 user_id 和 reward_id 的条目：
@NamedQuery(name="Favourite.byUserAndReward", query="from Reward r join r.favouriteUsers u where u.userId = ? and r.rewardId = ?")
问题是当我 运行 这个查询并将查询结果等同于类型 Reward 时，我得到以下异常：
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.xxxxxxx.model.Reward
at com.xxxxxxx.sevice.RewardService.addFavourite(RewardService.java:26)
at com.xxxxxxx.resources.RewardResource.addFavourite(RewardResource.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory.invoke(ResourceMethodInvocationHandlerFactory.java:81)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.run(AbstractJavaResourceMethodDispatcher.java:144)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:205)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
at org.glassfish.jersey.server.ServerRuntime.run(ServerRuntime.java:326)
at org.glassfish.jersey.internal.Errors.call(Errors.java:271)
at org.glassfish.jersey.internal.Errors.call(Errors.java:267)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
此查询的休眠查询日志如下：
Hibernate: select favouriteu0_.favourite_id as favourit2_3_0_, favouriteu0_.user_id as user_id1_3_0_, user1_.user_id as user_id1_2_1_ from FAVOURITE favouriteu0_ inner join USER user1_ on favouriteu0_.user_id=user1_.user_id where favouriteu0_.favourite_id=?
我想不出错误。有人可以帮忙吗？
编辑：我执行查询的部分是：
public Reward addFavourite(long userId, Reward favouriteReward) {
Object<Reward> rewardObject = new ObjectImpl<Reward>();
long favouriteId = favouriteReward.getRewardId();
// Check if favourited before.
// Below is the line that throws the exception.
Reward checkReward = rewardObject.getObjectByNamedQueryLongLong("Favourite.byUserAndReward", userId, favouriteId)
if (checkReward != null) {
return favouriteReward;
}
}
[Ljava.lang.Object 表示您的查询正在返回 array 个对象，而您正试图将其转换为一个对象。
更新：
由于您在没有 SELECT 子句的情况下进行查询并且还加入了 User、Hibernate returns Reward 和 User 对象，这就是为什么您得到 Object[].我可以想到两个解决方案。
- 您可以在
SELECT子句中提及您想要获得的对象，例如select r from Reward r join r.favouriteUsers u where u.userId = ? and r.rewardId = ? - 或者，您可以在查询中使用
fetch，例如from Reward r join fetch r.favouriteUsers u where u.userId = ? and r.rewardId = ?