Hibernate框架中數據庫多對多的演示

先是兩個實體類的創建，這裏我簡單用物品類和訂單類進行演示

package com.qiu.many_to_many;  //此處自己的工程包可以忽略

import java.util.Set;

/**
 * @author 邱
 * @2017年9月20日 多對多 備註：物品類
 */
public class Goods {

	private long id;
	private String type; //商品類型
	private String name;
	private double price;
	private Set<Order> set;

	public long getId() {
		return id;
	}

	public void setId(long id) {
		this.id = id;
	}

	public String getType() {
		return type;
	}

	public void setType(String type) {
		this.type = type;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public double getPrice() {
		return price;
	}

	public void setPrice(double price) {
		this.price = price;
	}

	public Set<Order> getSet() {
		return set;
	}

	public void setSet(Set<Order> set) {
		this.set = set;
	}

}

訂單的實體類

package com.qiu.many_to_many;

import java.util.Set;

/**
 * @author 邱
 * @2017年9月20日
 * 備註： 訂單類   多對多
 */
public class Order {

	private long id;//訂單編號
	private double money;
	private String address;
	private Set<Goods> set;

	public long getId() {
		return id;
	}

	public void setId(long id) {
		this.id = id;
	}

	public double getMoney() {
		return money;
	}

	public void setMoney(double money) {
		this.money = money;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public Set<Goods> getSet() {
		return set;
	}

	public void setSet(Set<Goods> set) {
		this.set = set;
	}
}

實體類比較簡單，大致看一下即可，主要是配置文件的編寫

物品類的配置文件

<?xml version="1.0" encoding="UTF-8"?>
<!--
  -->
  <!--約束文件-->
<!DOCTYPE hibernate-mapping PUBLIC
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- 多對多外鍵 -->
<hibernate-mapping package="com.qiu.many_to_many">

	<class name="Goods" table="tb_goods">
	 <id name="id">
	 <generator class="native"></generator>
	 </id>
		 
		
		<property name="name" length="20"/>	
		<property name="type" length="10"/>	
		<property name="price" />	
		
		<set name="set" table="tb_orderitem">
		<key column="gid"></key>
		<many-to-many class="Order" column="oid"></many-to-many>
		</set>
	</class>

</hibernate-mapping>

訂單的配置文件

<?xml version="1.0" encoding="UTF-8"?>
<!--
  -->
  <!--約束文件-->
<!DOCTYPE hibernate-mapping PUBLIC
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- 一對一外鍵 -->
<hibernate-mapping package="com.qiu.many_to_many">

	<class name="Order" table="tb_order">
	 <id name="id">
	 <generator class="native"></generator>
	 </id>
		 
		
		<property name="money" />	
		<property name="address" length="50"/>	
		<!--多對多  -->
		<!--集合類型的屬性
		name:屬性名
		table：關係表的表名 -->
		<set name="set" table="tb_orderitem">
		<!--當前的類在中間表的外鍵的名稱  -->
		<key column="oid"></key>
		<!--集合的泛型的類型，標記與誰是多對多，並且指示中間表中的外鍵名稱  -->
		<many-to-many class="Goods" column="gid"></many-to-many>
	</set>
	</class>

</hibernate-mapping>

全局配置文件把 四本一言搞清楚一般不會錯，記得把各個類的映射配置文件路徑加上

<?xml version="1.0" encoding="UTF-8"?>
<!--約束文件 -->
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<!-- 全局配置 -->
<hibernate-configuration>
	<!--Session工廠的設置，其實就是連接設置 -->
	<session-factory>

		<!--四本一言
		四大基本標籤：驅動、url、用戶名、密碼
		一言：方言，標記是哪一種數據庫 -->
		<!--1、數據庫驅動類名全稱 -->
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<!--2、數據庫的路徑  -->
		<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate_1710_moretable?characterEncoding=UTF-8</property>
		<!--3、數據庫用戶名  -->
		<property name="hibernate.connection.username">root</property>
		<!--4、密碼  -->
		<property name="hibernate.connection.password">123456</property>
		<!--5、方言，一定要和數據庫版本一致  -->
		<property name="hibernate.dialect">org.hibernate.dialect.MySQL57Dialect</property>
		<!--建表語句的執行：create\update  -->
		<property name="hibernate.hbm2ddl.auto">update</property>
		<!--顯示自動生成的sql語句  -->
		<property name="hibernate.show_sql">true</property>
		<!--格式化sql語句  -->
		<property name="hibernate.format_sql">true</property>
		<!--啓用安全Session，就是可以調用getCurrentSession  -->
		<property name="hibernate.current_session_context_class">thread</property>

                <!--多對多外鍵映射  -->
		<mapping resource="com/qiu/many_to_many/Goods.hbm.xml" />
		<mapping resource="com/qiu/many_to_many/Order.hbm.xml" />


	</session-factory>
</hibernate-configuration>

下面進行一些簡單的演示

package com.qiu.many_to_many;

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

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.qiu.utils.HibernateUtils;

/**
 * @author 邱
 * @2017年9月20日 
 * 備註：多對多的演示
 */
public class MyTest {

	private Session session;
	private Transaction tran;

	// 每次測試方法執行之前調用
	@Before
	public void bef() {
		session = HibernateUtils.openSession();
		tran = session.beginTransaction();
	}

	// 每次測試方法結束後調用
	@After
	public void aft() {
		tran.commit();
		session.close();
	}
	//多對多  新增：
	@Test
	public void test1(){
		Goods goods = new Goods();
		goods.setName("月餅");
		goods.setPrice(9.9);
		goods.setType("糕點");
		
		Order order = new Order();
		order.setMoney(9.9);
		order.setAddress("xxxxxxxxxxx");
		//這裏只需要添加一次即可，否則重複添加
		Set<Goods> set2 = new HashSet<>();
		set2.add(goods);
		order.setSet(set2);
		
		System.out.println("新增："+ session.save(order));
		System.out.println("新增："+ session.save(goods));
		
	}
	
	//多對多查詢
	@Test
	public void test2(){
		Order order2 = session.get(Order.class, 1l);
		System.out.println(order2.getAddress());
		for(Goods g : order2.getSet()){
			System.out.println(g.getName()+" "+g.getType());
		}
		Goods goods=session.get(Goods.class, 1l);
		System.out.println(goods.getName()+" "+goods.getPrice()+"----->");
		for(Order o : goods.getSet()){
			System.out.println(o.getAddress()+" "+o.getMoney());
		}
	}
}