hibernate之初学复合主键

Jar包什么的就看前面几篇文章，接下来介绍复合主键知识

首先是hibernate的配置文件hibernate,cfg.xml基本没有什么变化

<!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>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">123456</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/webproject</property><!--
                反正下面这段话我直接跑去hibernate.dialect包下复制文件路径的时候gg了要指定特定的方言
        --><property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>
        <property name="hibernate.show_sql">true</property><!--
        如果不存在就自动创建一个，如果存在就修改
        --><property name="hibernate.hbm2ddl.auto">update</property>
        <!--
                如果不加下面这句话，引入你自己写的配置文件，你将会很绝望
        --><mapping resource="com/shaoxin/cn/User.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

然后是User表的配置文件用于映射User.hbm.xml这里要注意主键不再是id

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping 
    package="com.shaoxin.cn">
    <class name="User"  table="user"><!--
    复合主键
    --><composite-id name="compositionUser" >
        <key-property name="username" column="username"></key-property>
        <key-property name="address" column="address"></key-property>
    </composite-id>
   <!--
        下面的分别是实体类中的属性对应数据库中的字段
        --><property name="age" column="age"></property>
    </class>
</hibernate-mapping>

然后是User实体类，这里面要把符合主键单独作为一个类写出去，并作为User实体类的一个属性

package com.shaoxin.cn;

public class User {
    private CompositionUser compositionUser;
    private int age;

    public CompositionUser getCompositionUser() {
        return compositionUser;
    }

    public void setCompositionUser(CompositionUser compositionUser) {
        this.compositionUser = compositionUser;
    }

    public int getAge() {
        return age;
    }

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

}

符合主键类要注意了一定要实现Serializable这个接口

package com.shaoxin.cn;

import java.io.Serializable;

public class CompositionUser implements Serializable {
    private String username;
    private String address;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getAddress() {
        return address;
    }

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

}

接下类就是测试类，没什么好说的

package com.shaoxin.cn;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.Test;

public class UserTest {
    @Test
    public void testUser() throws Exception {
        Session session = new Configuration().configure().buildSessionFactory()
                .openSession();
        Transaction tx = session.beginTransaction();
        CompositionUser compositionUser = new CompositionUser();
        compositionUser.setAddress("江西南昌");
        compositionUser.setUsername("邵欣");
        User user = new User();
        user.setCompositionUser(compositionUser);
        user.setAge(23);
        session.save(user);
        tx.commit();
        session.close();
    }
}