无限递归的问题：Jackson JSON和Hibernate JPA的问题。

当尝试将具有双向关联的JPA对象转换为JSON时，我一直收到：

org.codehaus.jackson.map.JsonMappingException: Infinite recursion (StackOverflowError)

我找到的仅有的东西是这个线程，基本上得出了建议，以避免双向关联。有人有解决这个Spring Bug的想法吗？

------ 编辑 2010-07-24 16:26:22 -------

代码片段：

业务对象1：

@Entity
@Table(name = "ta_trainee", uniqueConstraints = {@UniqueConstraint(columnNames = {"id"})})
public class Trainee extends BusinessObject {
    @Id
    @GeneratedValue(strategy = GenerationType.TABLE)
    @Column(name = "id", nullable = false)
    private Integer id;
    @Column(name = "name", nullable = true)
    private String name;
    @Column(name = "surname", nullable = true)
    private String surname;
    @OneToMany(mappedBy = "trainee", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @Column(nullable = true)
    private Set bodyStats;
    @OneToMany(mappedBy = "trainee", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @Column(nullable = true)
    private Set trainings;
    @OneToMany(mappedBy = "trainee", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @Column(nullable = true)
    private Set exerciseTypes;
    public Trainee() {
        super();
    }
    //... getters/setters ...
}

业务对象2：

import javax.persistence.*;
import java.util.Date;
@Entity
@Table(name = "ta_bodystat", uniqueConstraints = {@UniqueConstraint(columnNames = {"id"})})
public class BodyStat extends BusinessObject {
    @Id
    @GeneratedValue(strategy = GenerationType.TABLE)
    @Column(name = "id", nullable = false)
    private Integer id;
    @Column(name = "height", nullable = true)
    private Float height;
    @Column(name = "measuretime", nullable = false)
    @Temporal(TemporalType.TIMESTAMP)
    private Date measureTime;
    @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinColumn(name="trainee_fk")
    private Trainee trainee;
}

控制器：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServletResponse;
import javax.validation.ConstraintViolation;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
@Controller
@RequestMapping(value = "/trainees")
public class TraineesController {
    final Logger logger = LoggerFactory.getLogger(TraineesController.class);
    private Map<Long, Trainee> trainees = new ConcurrentHashMap<Long, Trainee>();
    @Autowired
    private ITraineeDAO traineeDAO;
    /**
     * Return json repres. of all trainees
     */
    @RequestMapping(value = "/getAllTrainees", method = RequestMethod.GET)
    @ResponseBody        
    public Collection getAllTrainees() {
        Collection allTrainees = this.traineeDAO.getAll();
        this.logger.debug("A total of " + allTrainees.size() + "  trainees was read from db");
        return allTrainees;
    }    
}

实习生DAO的JPA实现：

@Repository
@Transactional
public class TraineeDAO implements ITraineeDAO {
    @PersistenceContext
    private EntityManager em;
    @Transactional
    public Trainee save(Trainee trainee) {
        em.persist(trainee);
        return trainee;
    }
    @Transactional(readOnly = true)
    public Collection getAll() {
        return (Collection) em.createQuery("SELECT t FROM Trainee t").getResultList();
    }
}

persistence.xml

    
        false