我一直在搞怪它并使用它搜索了大约4天,我对Hibernate注释如何与JPA注释一起工作感到疯狂。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; } }
我将整个代码粘贴到这里,以便您可以看到导入的来源。我认为问题就在那里。 重要提示 :我使用的JoinTable是Hibernate Docs建议的
JoinTable
好!现在,我创建了一个Student包含两个电话号码的,并将其正确保存在数据库中。这将创建以下内容:
Student
studentid | studentname -----------+------------- 2 | foo (1 rows)
学生电话
student_id | phone_id ------------+--------- 2 | 3 2 | 4 (2 rows)
phoneid | phonenumber | phonetyp ---------+-------------+--------- 4 | 9889343423 | mobile 3 | 32354353 | house (2 rows)
问题来了。如果我删除了客户端的一个电话号码(移动电话)并将分离的学生实体发送到服务器并执行更新,请hibernate以下内容:
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,它只是删除联接表中的条目,而不会删除电话表中的电话条目本身。所以现在表看起来像这样:
student_id | phone_id ------------+--------- 2 | 3 (1 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也删除电话表中的电话号码?
更新 我正在使用PostgreSQL
经过与Hibernate的进一步合作,我终于意识到我没有正确实现,equals并且hashCode函数在CRUD操作上的Hibernate Generated Sequence造成了一些麻烦。在这篇很棒的文章中描述(并解决了)这个问题(我认为必须阅读)
equals
hashCode
最好的祝福