框架:Hibernate单向多对多

一、假定一个人只有多个地址，一个地址对应多个人，那么人和地址对应关系为多对多。

二、

       1、添加依赖包，参考上篇文章hibernate+mysql入门使用

       2、初始化数据库

DROP  DATABASE  IF  EXISTS  moy_hibernate;
CREATE  DATABASE  moy_hibernate   CHARACTER SET UTF8;

      3、新建实体类Address和Person

package com.moy.hibernate4.entity;

import org.hibernate.annotations.Cascade;

import javax.persistence.*;

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

/**
 * [Project]:moy-gradle-project  <br/>
 * [Email]:moy25@foxmail.com  <br/>
 * [Date]:2018/2/25  <br/>
 * [Description]:  <br/>
 *
 * @author YeXiangYang
 */
@Entity
@Table(name = "t_address")
public class Address {

    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int addressId;
    private String addressDetail;

    public int getAddressId() {
        return addressId;
    }

    public void setAddressId(int addressId) {
        this.addressId = addressId;
    }

    public String getAddressDetail() {
        return addressDetail;
    }

    public void setAddressDetail(String addressDetail) {
        this.addressDetail = addressDetail;
    }

    @Override
    public String toString() {
        return "Address{" +
                "addressId=" + addressId +
                ", addressDetail='" + addressDetail + ''' +
                '}';
    }
}

package com.moy.hibernate4.entity;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

/**
 * [Project]:moy-gradle-project  <br/>
 * [Email]:moy25@foxmail.com  <br/>
 * [Date]:2018/2/25  <br/>
 * [Description]:  <br/>
 *
 * @author YeXiangYang
 */
@Table(name = "t_person")
@Entity
public class Person {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String name;
    private int age;
    @ManyToMany(targetEntity = Address.class)
    @JoinTable(name = "t_person_address",
            joinColumns = @JoinColumn(name = "person_id", referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(name = "address_id", referencedColumnName = "id"))
    private Set<Address> address = new HashSet<>();

    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 int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Set<Address> getAddress() {
        return address;
    }

    public void setAddress(Set<Address> address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name='" + name + ''' +
                ", age=" + age +
                ", address=" + address +
                '}';
    }
}

      4、新建配置文件hibernate.cfg.xml和log4j.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!-- 指定连接数据库所用的驱动 -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <!-- 指定连接数据库的url，其中hibernate是本应用连接的数据库名 -->
        <property name="connection.url">jdbc:mysql://localhost:3306/moy_hibernate</property>
        <!-- 指定连接数据库的用户名 -->
        <property name="connection.username">root</property>
        <!-- 指定连接数据库的密码 -->
        <property name="connection.password">123</property>
        <!-- 指定数据库方言 -->
        <property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
        <!-- 根据需要自动创建数据表 -->
        <property name="hbm2ddl.auto">update</property>
        <!-- 显示Hibernate持久化操作所生成的SQL -->
        <property name="show_sql">true</property>
        <!-- 将SQL脚本进行格式化后再输出 -->
        <!--<property name="hibernate.format_sql">true</property>-->
        <!-- 罗列所有持久化类的类名 -->
        <mapping class="com.moy.hibernate4.entity.Person"></mapping>
        <mapping class="com.moy.hibernate4.entity.Address"></mapping>
    </session-factory>
</hibernate-configuration>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
    <appender name="console" class="org.apache.log4j.ConsoleAppender">
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d %-5p %-5c{3}:%L %x %n-> %m%n"/>
        </layout>
    </appender>
    <root>
        <priority value="DEBUG"/>
        <appender-ref ref="console"/>
    </root>
</log4j:configuration>

      5、为了方便测试，编写一个获取Session的工具类Hibernate4Utils

package com.moy.hibernate4.util;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

import java.util.Objects;

public abstract class Hibernate4Utils {

    static {
        try {
            Configuration conf = new Configuration().configure();
            ServiceRegistry registry = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
            sessionFactory = conf.buildSessionFactory(registry);
        } catch (Throwable e) {
            throw e;
        }
    }

    public static final SessionFactory sessionFactory;

    public static final ThreadLocal<Session> sessionThread = new ThreadLocal<>();

    /**
     * 获取当前线程安全Session
     */
    public static Session getCurrentSession() {
        Session session = sessionThread.get();
        if (Objects.isNull(session)) {
            session = sessionFactory.openSession();
            sessionThread.set(session);
        }
        return session;
    }

    /**
     * 关闭Session
     */
    public static void closeCurrentSession() {
        Session session = sessionThread.get();
        if (Objects.nonNull(session)) {
            session.close();
        }
        sessionThread.set(null);
    }
}

      6、新建测试类ManyToMangTest测试

package com.moy.hibernate4.entity;

import com.moy.hibernate4.util.Hibernate4Utils;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

/**
 * [Project]:moy-gradle-project  <br/>
 * [Email]:moy25@foxmail.com  <br/>
 * [Date]:2018/2/25  <br/>
 * [Description]:  <br/>
 *
 * @author YeXiangYang
 */
public class ManyToMangTest {

    Session session;
    Transaction transaction;

    @Before
    public void before() {
        session = Hibernate4Utils.getCurrentSession();
        transaction = session.beginTransaction();
    }

    @After
    public void after() {
        transaction.commit();
        Hibernate4Utils.closeCurrentSession();
    }

    @Test
    public void test() {

        Address firstAddress = new Address();
        firstAddress.setAddressDetail(firstAddress.toString());
        session.persist(firstAddress);

        Address secondAddress = new Address();
        secondAddress.setAddressDetail(secondAddress.toString());
        session.persist(secondAddress);

        Person firstPerson = new Person();
        firstPerson.setName("测试多对多");
        firstPerson.setAge(233);
        firstPerson.getAddress().add(firstAddress);
        firstPerson.getAddress().add(secondAddress);
        session.persist(firstPerson);

        Person secondPerson = new Person();
        secondPerson.setName("测试多对多");
        secondPerson.setAge(122);
        secondPerson.getAddress().add(firstAddress);
        secondPerson.getAddress().add(secondAddress);
        session.persist(secondPerson);
    }
}

yexiangyang

moyyexy@gmail.com

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