mybatis多表关联配置

首先需要的jar包

mybatis-3.4.1

配置文件（mybatis.cfg.xml）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

<typeAliases>
<typeAlias alias="mybatis1" type="entity.mybatis1"/>
<typeAlias alias="types" type="entity.types"/>
</typeAliases>

<!-- 选择默认的连接方式 -->
<environments default="myb">

<environment id="myb">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/test"/>
<property name="username" value="root"/>
<property name="password" value="accp"/>
</dataSource>
</environment>

</environments>

<mappers>
<mapper resource="entity/mybatis1Mapper.xml"/>
</mappers>
</configuration>

Mybatis1.java

package entity;

public class mybatis1 {
    
    private int id;
    private String name;
    private int age;
    private types types;
    public types getTypes() {
        return types;
    }
    public void setTypes(types types) {
        this.types = types;
    }
    public int getId() {
        return id;
    }
    public void setId(int 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 mybatis1(String name, int age) {
        super();
        this.name = name;
        this.age = age;
    }
    public mybatis1(){}

}

Types.java

package entity;

import java.util.ArrayList;
import java.util.List;

public class types {
    
    private int id;
    private String tname;
    private List<mybatis1> mybatis=new ArrayList<mybatis1>();
    public List<mybatis1> getMybatis(){
        return mybatis;
    }
    public void setMybatis(List<mybatis1> mybatis) {
        this.mybatis = mybatis;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getTname() {
        return tname;
    }
    public void setTname(String tname) {
        this.tname = tname;
    }
}

mybatis1Mapper.xml(配置多对一关系)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="entity.mybatis1">

<resultMap type="mybatis1" id="mylist">
<id property="id" column="id"></id>
<result column="name" property="name"/>
<result column="age" property="age"/>
<!-- 多对一的关系 -->
        <!-- property: 指的是属性的值, javaType：指的是属性的类型-->
        <association property="types" javaType="types">
            <id column="id" property="id"/>
            <result column="tname" property="tname"/>
        </association>
</resultMap>
<select id="selectall" resultMap="mylist">
select m.*,t.tname tname from mybatis1 m ,types t 
where m.typeid=t.id
</select>



<insert id="addmybatis" parameterType="entity.mybatis1">
insert into mybatis1(name,age) values(#{name},#{age})
</insert>

</mapper>

typesMapper.xml(配置一对多关系)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="entity.types">

<resultMap type="types" id="mytype">
<id column="id" property="id"></id>
<result column="tname" property="tname"/>
    <!-- 一对多的关系 -->
        <!-- property: 指的是集合属性的值, ofType：指的是集合中元素的类型 -->
        <collection property="mybatis" ofType="mybatis1">
            <id column="id" property="id"/>
            <result column="name" property="name"/>
            <result column="age" property="age"/>
        </collection>
</resultMap>

<select id="selectalltype" resultMap="mytype">
select m.*,t.tname tname from mybatis1 m ,types t where m.typeid=t.id
</select>
</mapper>

test_mybatis.java(测试)

package test;

import java.io.IOException;
import java.io.Reader;
import java.util.List;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import entity.mybatis1;

public class test_mybatis {
    
    public static void main(String[] args) {
        try {
            Reader r= Resources.getResourceAsReader("mybatis.cfg.xml");
        SqlSessionFactoryBuilder sfb=new SqlSessionFactoryBuilder();
        SqlSessionFactory sf=sfb.build(r);
        SqlSession session=sf.openSession();
          
//            mybatis1 my=new mybatis1("zs", 12);
//             session.insert("entity.mybatis1.addmybatis", my);
//             session.commit();
        String d="d";
        List<mybatis1> list=session.selectList("selectall");
        System.out.println(list.size());
        for(mybatis1 m:list){
            System.out.println(m.getTypes().getTname()+"=="+m.getName());
        }
             session.close();
        
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}