Hibernate 注解（Annotations 四）多对多双向注解

注解（Annotation），也叫元数据。一种代码级别的说明。它是JDK1.5及以后版本引入的一个特性，与类、接口、枚举是在同一个层次。它可以声明在包、类、字段、方法、局部变量、方法参数等的前面，用来对这些元素进行说明，注释。

接下来讲解多对多双向注解：

我以用户和房子作为示例讲解。

第一步：准备实体类

House（房间表）

package cn.manytomany.entity;

import javax.persistence.*;

import java.util.HashSet;

import java.util.Set;

/**

 * Created by accp on 2017/2/10.

 */

@Entity

@Table(name = "House")

public class House {

    @Id

    @GeneratedValue

    private Integer id;

    @Column

    private String title;

    @Column

    private String description;

    @Column

    private Integer price;

    @Column

    private String pubdate;

    @Column

    private Integer floorage;

    @Column

    private String contact;

    @Column

    private Integer userid;

    @Column

    private Integer streetid;

    @Column

    private Integer typeid;

    /**

     * 将控制权交给主表

     */

    @ManyToMany(mappedBy = "houses")

    private Set<Users> userss=new HashSet<Users>();

    public Integer getId() {

        return id;

    }

    public void setId(Integer id) {

        this.id = id;

    }

    public String getTitle() {

        return title;

    }

    public void setTitle(String title) {

        this.title = title;

    }

    public String getDescription() {

        return description;

    }

    public void setDescription(String description) {

        this.description = description;

    }

    public Integer getPrice() {

        return price;

    }

    public void setPrice(Integer price) {

        this.price = price;

    }

    public String getPubdate() {

        return pubdate;

    }

    public void setPubdate(String pubdate) {

        this.pubdate = pubdate;

    }

    public Integer getFloorage() {

        return floorage;

    }

    public void setFloorage(Integer floorage) {

        this.floorage = floorage;

    }

    public String getContact() {

        return contact;

    }

    public void setContact(String contact) {

        this.contact = contact;

    }

    public Integer getUserid() {

        return userid;

    }

    public void setUserid(Integer userid) {

        this.userid = userid;

    }

    public Integer getStreetid() {

        return streetid;

    }

    public void setStreetid(Integer streetid) {

        this.streetid = streetid;

    }

    public Integer getTypeid() {

        return typeid;

    }

    public void setTypeid(Integer typeid) {

        this.typeid = typeid;

    }

    public Set<Users> getUserss() {

        return userss;

    }

    public void setUserss(Set<Users> userss) {

        this.userss = userss;

    }

}

User（用户表）:

package cn.manytomany.entity;

import javax.persistence.*;

import java.util.HashSet;

import java.util.Set;

/**

 * Created by accp on 2017/2/10.

 */

@Entity

@Table(name = "Users")

public class Users {

    @Id

    @GeneratedValue

    private Integer id;

    @Column

    private String name;

    @Column

    private String password;

    @Column

    private String telephone;

    @Column

    private String username;

    @Column

    private String isadmin;

    /**

     * 以房间表作为主导  设置级联

     * 只需要保存用户  即可保存房间

     */

    @ManyToMany(cascade = {CascadeType.ALL})

    @JoinTable(

            name = "RUHS",

            joinColumns =@JoinColumn(name = "RUID"),

            inverseJoinColumns = @JoinColumn(name = "RHID")

    )

    private Set<House> houses=new HashSet<House>();

    public Integer getId() {

        return id;

    }

    public void setId(Integer id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public String getPassword() {

        return password;

    }

    public void setPassword(String password) {

        this.password = password;

    }

    public String getTelephone() {

        return telephone;

    }

    public void setTelephone(String telephone) {

        this.telephone = telephone;

    }

    public String getUsername() {

        return username;

    }

    public void setUsername(String username) {

        this.username = username;

    }

    public String getIsadmin() {

        return isadmin;

    }

    public void setIsadmin(String isadmin) {

        this.isadmin = isadmin;

    }

    public Set<House> getHouses() {

        return houses;

    }

    public void setHouses(Set<House> houses) {

        this.houses = houses;

    }

}

第二步：在hibernate.cfg.xml文件中配置<mapping>节点

<mapping class="cn.manytomany.entity.House"/>

<mapping class="cn.manytomany.entity.Users"/>

第三步：书写测试类

package cn.manytomany.test;

import cn.manytomany.entity.House;

import cn.manytomany.entity.Users;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.cfg.Configuration;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

/**

 * Created by accp on 2017/2/10.

 */

public class DemoTest {

    Configuration cfg;

    Session session;

    Transaction tx;

    @Before

    public void myBefore(){

        cfg=new Configuration().configure();

        SessionFactory factory = cfg.buildSessionFactory();

        session = factory.openSession();

        tx=session.beginTransaction();

    }

    @After

    public void myAfter(){

        tx.commit();

        session.close();

    }

    @Test

    public void  add(){

        Users users1=new Users();

        users1.setName("hiber1");

        users1.setPassword("");

        users1.setTelephone("");

        users1.setUsername("Jim");

        users1.setIsadmin("");

        Users users2=new Users();

        users2.setName("hiber2");

        users2.setPassword("");

        users2.setTelephone("");

        users2.setUsername("Jim2");

        users2.setIsadmin("");

        House house=new House();

        house.setTitle("元宵佳节房屋便宜");

        house.setDescription("经济实惠，元宵佳宿！");

        house.setPrice();

        house.setPubdate("2017-02-11");

        house.setFloorage();

        house.setContact("圆圆");

        house.setStreetid();

        house.setTypeid();

        House house2=new House();

        house2.setTitle("共度元宵");

        house2.setDescription("便宜喽，赶快下手！");

        house2.setPrice();

        house2.setPubdate("2017-01-10");

        house2.setFloorage();

        house2.setContact("佳佳");

        house2.setStreetid();

        house2.setTypeid();

       /*关联关系

       * 同一个房间对应不同的用户

       *

       * 同一个用户对应不同的房间

       * */

        users1.getHouses().add(house);

        users1.getHouses().add(house2);

        users2.getHouses().add(house2);

        session.save(users1);

        session.save(users2);

    }

}

在配置多对多时要选取那张表生成第三张表非常重要，在第三张表的外键也要搞清楚。

巴特西

Hibernate 注解（Annotations 四）多对多双向注解

最新文章

热门文章