java - HashCode 循环调用 : OneToMany JPA

Question

我想执行这个方法:

@RequestMapping(value = "/list", method = RequestMethod.GET)
public List<Project> listProjects() {

    return ps.findAllProjects();
}

在我的 DAO 中我有:

@Repository
public interface ProjectDAO extends JpaRepository<Project, Long> {
    List<Project> findAllProjectsByShowableTrue();  }

在我的实体中:

<强>1。项目:

@Transactional
@Entity
public class Project implements Serializable{

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private Long id;

private String name;

private boolean showable = true;

@OneToMany(mappedBy="project", fetch = FetchType.EAGER)
private Set<Collaborator> collaborators = new HashSet<>();

@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((collaborators == null) ? 0 : collaborators.hashCode());
result = prime * result + ((id == null) ? 0 : id.hashCode());
      }
//Getters & setters        
}

<强>2。合作者:

@Entity
public class Collaborator implements Serializable{

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinColumn(name = "ProjectID" , nullable = true)
private Project project;

@Override
public int hashCode() {
      final int prime = 31;
      int result = 1;
      result = prime * result + ((id == null) ? 0 : id.hashCode());
      result = prime * result + ((project == null) ? 0 : project.hashCode());
return result;
}
//Getters & setters      
}

但是我收到了这个错误:

HTTP Status 500 - Handler dispatch failed; nested exception is java.lang.StackOverflowError

root cause
java.lang.StackOverflowError
java.net.AbstractPlainSocketImpl.available(Unknown Source)
java.net.SocketInputStream.available(Unknown Source)
.........
gestionprojet.java.entities.beans.Project.hashCode(Project.java:179)
gestionprojet.java.entities.beans.Collaborator.hashCode(Collaborator.java:88)

现在，当协作者表为空时:请求运行完美，但是当我将协作者添加到项目时，所有相关请求都被破坏了。

附言: HashCode() 和 Equals() 方法是自动生成的。

如有任何帮助，我们将不胜感激。坦克你。

Answer 1

您的 Project 类正在调用 collaborators.hashCode() 而您的 Collaborators 类正在调用 project.hashCode()。

所以当一个项目有一个合作者时，你会得到一个无限循环，因为 Project 调用 Collaborator，Collaborator 调用 Project等等...