hibernate 多对多双向

最新推荐文章于 2019-08-11 22:40:41 发布

坚持吧骚年

最新推荐文章于 2019-08-11 22:40:41 发布

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本文链接：https://blog.youkuaiyun.com/huangning1995/article/details/91348570

本文详细介绍了在Hibernate中如何配置双向的ManyToMany关联关系，通过具体的Java代码示例，展示了Teacher与Student类之间的关联配置，包括使用@ManyToMany、@JoinTable和mappedBy属性的方法。

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Student可以有多个Teacher

Teacher可以有多个Student

package com.bjsxt.hibernate;

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.ManyToMany;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
public class Teacher {
	private int id;
	private String name;
	private Set<Student> students = new HashSet<Student>();
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	@ManyToMany
	@JoinTable(name="t_s",
		joinColumns={@JoinColumn(name="teacher_id")},
		inverseJoinColumns={@JoinColumn(name="student_id")}
		)
	public Set<Student> getStudents() {
		return students;
	}
	public void setStudents(Set<Student> students) {
		this.students = students;
	}
}

package com.bjsxt.hibernate;

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

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

@Entity
public class Student {
	private int id;
	private String name;
	private Set<Teacher> teachers = new HashSet<Teacher>();
	@ManyToMany(mappedBy="students")
	public Set<Teacher> getTeachers() {
		return teachers;
	}
	public void setTeachers(Set<Teacher> teachers) {
		this.teachers = teachers;
	}
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
}

总结：

对于这种双向的关联关系，如果一方一句配置好了，另外一方只需要配置一下mappedBy就完事了，非常方便。