Question

我一直在搞乱这个并且谷歌搜索它大约4天而且我对于Hibernate注释如何与JPA注释一起工作变得疯狂。我有两个非常简单的实体：

学生

package com.vaannila.student;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.OneToMany;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;

@Entity
public class Student {

    @Id
    @GeneratedValue
    private long studentId;
    private String studentName;
    @OneToMany(orphanRemoval = true)
    @Cascade(CascadeType.ALL)
    @JoinTable(name = "STUDENT_PHONE", joinColumns = { @JoinColumn(name = "STUDENT_ID") }, inverseJoinColumns = { @JoinColumn(name = "PHONE_ID") })
    private Set<Phone> studentPhoneNumbers = new HashSet<Phone>(0);

    public Student() {
    }

    public Student(String studentName, Set<Phone> studentPhoneNumbers) {
        this.studentName = studentName;
        this.studentPhoneNumbers = studentPhoneNumbers;
    }

    public long getStudentId() {
        return this.studentId;
    }

    public void setStudentId(long studentId) {
        this.studentId = studentId;
    }

    public String getStudentName() {
        return this.studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    public Set<Phone> getStudentPhoneNumbers() {
        return this.studentPhoneNumbers;
    }

    public void setStudentPhoneNumbers(Set<Phone> studentPhoneNumbers) {
        this.studentPhoneNumbers = studentPhoneNumbers;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + (int) (studentId ^ (studentId >>> 32));
        result = prime * result + ((studentName == null) ? 0 : studentName.hashCode());
        result = prime * result + ((studentPhoneNumbers == null) ? 0 : studentPhoneNumbers.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;
        Student other = (Student) obj;
        if (studentId != other.studentId) return false;
        if (studentName == null) {
            if (other.studentName != null) return false;
        }
        else if (!studentName.equals(other.studentName)) return false;
        if (studentPhoneNumbers == null) {
            if (other.studentPhoneNumbers != null) return false;
        }
        else if (!studentPhoneNumbers.equals(other.studentPhoneNumbers)) return false;
        return true;
    }

}

电话

package com.vaannila.student;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Phone {

    @Id
    @GeneratedValue
    private long phoneId;
    private String phoneType;
    private String phoneNumber;

    public Phone() {
    }

    public Phone(String phoneType, String phoneNumber) {
        this.phoneType = phoneType;
        this.phoneNumber = phoneNumber;
    }

    public long getPhoneId() {
        return this.phoneId;
    }

    public void setPhoneId(long phoneId) {
        this.phoneId = phoneId;
    }

    public String getPhoneType() {
        return this.phoneType;
    }

    public void setPhoneType(String phoneType) {
        this.phoneType = phoneType;
    }

    public String getPhoneNumber() {
        return this.phoneNumber;
    }

    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + (int) (phoneId ^ (phoneId >>> 32));
        result = prime * result + ((phoneNumber == null) ? 0 : phoneNumber.hashCode());
        result = prime * result + ((phoneType == null) ? 0 : phoneType.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;
        Phone other = (Phone) obj;
        if (phoneId != other.phoneId) return false;
        if (phoneNumber == null) {
            if (other.phoneNumber != null) return false;
        }
        else if (!phoneNumber.equals(other.phoneNumber)) return false;
        if (phoneType == null) {
            if (other.phoneType != null) return false;
        }
        else if (!phoneType.equals(other.phoneType)) return false;
        return true;
    }

}

我在这里粘贴了整个代码，因此您可以看到导入的来源。我认为问题在那里。重要：我正在使用JoinTable作为Hibernate Docs推荐

确定！现在我创建一个带有两个电话号码的Student并将其正确保存在数据库中。这会创建以下内容：

学生

 studentid | studentname
-----------+-------------
         2 | foo
(1 rows)

student_phone

 student_id | phone_id
------------+---------
          2 |        3
          2 |        4
(2 rows)

电话

 phoneid | phonenumber | phonetyp
---------+-------------+---------
       4 | 9889343423  | mobile
       3 | 32354353    | house
(2 rows)

这就是问题所在。如果我删除客户端中的一个电话号码（移动）并将分离的学生实体发送到服务器并执行更新，请执行以下操作：

Hibernate: update Student set studentName=? where studentId=?
Hibernate: update Phone set phoneNumber=?, phoneType=? where phoneId=?
Hibernate: delete from STUDENT_PHONE where STUDENT_ID=?
Hibernate: insert into STUDENT_PHONE (STUDENT_ID, PHONE_ID) values (?, ?)

如您所见，它只是删除了连接表中的条目，但没有删除电话表中的电话条目本身。所以现在表格看起来像这样：

学生

 studentid | studentname
-----------+-------------
         2 | foo
(1 rows)

student_phone

 student_id | phone_id
------------+---------
          2 |        3
(1 rows)

电话

 phoneid | phonenumber | phonetyp
---------+-------------+---------
       4 | 9889343423  | mobile
       3 | 32354353    | house
(2 rows)

问题：这是正常行为吗？即使级联删除和孤立删除设置为true？我如何实现Hibernate也删除了电话表中的电话号码？

更新我正在使用PostgreSQL

Answer 1

在进一步使用Hibernate之后，我意识到我没有正确实现equals和hashCode函数，导致在CRUD操作上使用Hibernate Generated Sequence出现一些问题。这个问题在great article（我认为必须阅读）

中描述（并解决）了

祝你好运

Answer 2

这与

非常相似

http://www.mkyong.com/hibernate/cascade-jpa-hibernate-annotation-common-mistake/

您正在混合JPA和hibernate注释。我会坚持使用一个（最好是JPA，但博客文章坚持使用hibernate），并以这种方式建立关系：

@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)

Hibernate 3.6.10不会通过OneToMany JoinTable级联删除

2 个答案: