Hibernate框架jpa双向多对多配置，操作

package bean;

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

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
@Entity
@Table(name="sys_user")
public class User {
	@Id
	@Column(name="user_id")
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private Long user_id;//'用户id',
	@Column(name="user_code")
	private String user_code;// '用户账号',
	@Column(name="user_name")
	private String user_name;// '用户名称',
	
	//外键
	// 配置多对多的关系
		// 有Role的集合
		@ManyToMany(targetEntity=Role.class,cascade=CascadeType.PERSIST)
		// 维护外键
		/*name: 中间表的名称
		joinColumns: 自己在中间表的配置
		inverseJoinColumns:	对方在中间表的配置
		*/
		@JoinTable(name="sys_user_role",
							joinColumns= {
									// name:自己在中间表的外键字段名
									// referencedColumnName: 指向自己的主键字段名
									@JoinColumn(name="user_id",referencedColumnName="user_id")
							},
							inverseJoinColumns= {
									/*name:对方在中间表的外键字段名
									referencedColumnName:指向对方的主键字段名*/
									@JoinColumn(name="role_id",referencedColumnName="role_id")
									
							})
	private Set<Role> role=new HashSet<Role>();
	public Long getUser_id() {
		return user_id;
	}
	public void setUser_id(Long user_id) {
		this.user_id = user_id;
	}
	public String getUser_code() {
		return user_code;
	}
	public void setUser_code(String user_code) {
		this.user_code = user_code;
	}
	public String getUser_name() {
		return user_name;
	}
	public void setUser_name(String user_name) {
		this.user_name = user_name;
	}

	public Set<Role> getRole() {
		return role;
	}
	public void setRole(Set<Role> role) {
		this.role = role;
	} 
}

package bean;

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

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
//类上:
//@Entity // 当前类是持久化类
//@Table(name="表名") //当前持久化类和哪个表做映射
//
//属性:
//@Id //当前的属性是oid属性
//@Column(name="主键名")// 和表的哪个字段做映射
//@GeneratedValue(strategy=GenerationType.IDENTITY) //指定oid的增长策略
//
//
// @Column(name="字段名") // 其它属性和表中的字段映射
@Entity
@Table(name="sys_role")
public class Role {
	@Id
	@Column(name="role_id")
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private Long role_id;
	@Column(name="role_name")
	private String role_name;//'角色名称',
	@Column(name="role_memo")
	private String role_memo;// '备注',
	
	//外键
	// 配置多对多
		// 有user的集合
		/*targetEntity:对象的字节码文件对象
		mappedBy:自己在对方中的属性名
		*/
	@ManyToMany(targetEntity=User.class,mappedBy="role")
	private Set<User> users=new HashSet<User>();
	
	public Long getRole_id() {
		return role_id;
	}
	public void setRole_id(Long role_id) {
		this.role_id = role_id;
	}
	public String getRole_name() {
		return role_name;
	}
	public void setRole_name(String role_name) {
		this.role_name = role_name;
	}
	public String getRole_memo() {
		return role_memo;
	}
	public void setRole_memo(String role_memo) {
		this.role_memo = role_memo;
	}
	public Set<User> getUsers() {
		return users;
	}
	public void setUsers(Set<User> users) {
		this.users = users;
	}
	
}

JPA操作

package test;

import javax.persistence.CascadeType;
import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.ManyToMany;

import org.junit.Test;

import bean.Role;
import bean.User;
import utils.JPAUtils;

public class demo4 {
//JPA双向多对多操作
	@Test//普通保存
	public void t1() {
		EntityManager en = JPAUtils.getEntityManager();
		EntityTransaction tr = en.getTransaction();
		tr.begin();
		//保存两个用户
		User u1=new User();
		u1.setUser_name("小明");
		User u2=new User();
		u2.setUser_name("大柱");
		//三个职业
		Role r1=new Role();
		r1.setRole_name("学生");
		Role r2=new Role();
		r2.setRole_name("医生");
		Role r3=new Role();
		r3.setRole_name("老师");
		
		//用户关联职业
		u1.getRole().add(r1);
		u1.getRole().add(r2);
		
		u2.getRole().add(r1);
		u2.getRole().add(r3);
		//职业关联用户
		r1.getUsers().add(u1);
		r1.getUsers().add(u2);
		r2.getUsers().add(u1);
		r2.getUsers().add(u2);
		//保存所有数据
		en.persist(u1);
		en.persist(u2);
		en.persist(r1);
		en.persist(r2);
		en.persist(r3);
	
		tr.commit();
		en.close();
	}
	//级联保存
	//在保存的一方加上
	//@ManyToMany(cascade=CascadeType.PERSIST)
	@Test
	public void t2(){
		EntityManager en = JPAUtils.getEntityManager();
		EntityTransaction tr = en.getTransaction();
		tr.begin();
		//保存两个用户
		User u1=new User();
		u1.setUser_name("小明");
		User u2=new User();
		u2.setUser_name("大柱");
		//三个职业
		Role r1=new Role();
		r1.setRole_name("学生");
		Role r2=new Role();
		r2.setRole_name("医生");
		Role r3=new Role();
		r3.setRole_name("老师");
		
		//用户关联职业
		u1.getRole().add(r1);
		u1.getRole().add(r2);
		
		u2.getRole().add(r1);
		u2.getRole().add(r3);
		//职业关联用户
		r1.getUsers().add(u1);
		r1.getUsers().add(u2);
		r2.getUsers().add(u1);
		r2.getUsers().add(u2);
		//保存用户关联的数据
		en.persist(u1);
		en.persist(u2);
		
		tr.commit();
		en.close();
	}
	//修改单条数据
	@Test
	public void t3() {
		EntityManager en = JPAUtils.getEntityManager();
		EntityTransaction tr = en.getTransaction();
		tr.begin();
		//获取用户
		User user = en.find(User.class, 1L);
		//获取要删除的职业
		Role role = en.find(Role.class, 3L);
		//获取要修改的职业
		Role role3 = en.find(Role.class, 1L);
		//删除职业
		user.getRole().remove(role);
		//添加职业
		user.getRole().add(role3);

		tr.commit();
		en.close();
	}
}