java Hibernate HttpMessageNotWritableException

5 月，4 周 Questions & Answers 597

我目前正在SpringMVC4.2.3中使用Hibernate4.3.5。我有两个模型User和Client，其中User的id是Client的外键

在User类中：

@Repository
@Transactional
public class UserDAOImpl implements UserDAO {

@Autowired
private SessionFactory sessionFactory;

protected SessionFactory getSessionFactory() {
    try {
        return (SessionFactory) new InitialContext().lookup("SessionFactory");
    } catch (Exception e) {
        log.error("Could not locate SessionFactory in JNDI", e);
        throw new IllegalStateException("Could not locate SessionFactory in JNDI");
    }
}

@OneToMany(fetch = FetchType.EAGER, mappedBy = "user")
public Set<Client> getClients() {
    return this.clients;
}

......
}

在{}中，我设置：

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "user_id", nullable = false)
public User getUser() {
    return this.user;
}

SessionFactory在root-context.xml中定义。这样，我应该能够从分离的User对象获取clients，对吗？但是，当我运行此代码时：

results.addAll(userDAO.findById(id).getClients());

它返回了以下异常：

WARN : org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver - Failed to write HTTP message: org.springframework.http.converter.HttpMessageNotWritableException: Could not write content: Infinite recursion (StackOverflowError) (through reference chain: com.hersbitcloud.cancercloud.models.Client["user"]->com.hersbitcloud.cancercloud.models.User["clientss"]->org.hibernate.collection.internal.PersistentSet[0]->com.hersbitcloud.cancercloud.models.Client["user"]->com.hersbitcloud.cancercloud.models.User["clients"]->org.hibernate.collection.internal.PersistentSet[0]-
java.lang.IllegalStateException: Cannot call sendError() after the response has been committed

堆栈跟踪非常长，我认为这意味着当我获取User时，它同时获取Client，因为它是EAGER。然后User对象作为Client的内部对象再次被获取，即使它被设置为LAZY。这个过程会反复出现，永不停止

我理解LAZY在会话中只获取内容。我的问题是，为什么到User的会话从未过期

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java Hibernate HttpMessageNotWritableException

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