package com.how2java.pojo;

public class Product {
	private int id;
	private String name;
	private float price;
	private Category category;
	
	public Category getCategory() {
		return category;
	}
	public void setCategory(Category category) {
		this.category = category;
	}
	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 float getPrice() {
		return price;
	}
	public void setPrice(float price) {
		this.price = price;
	}
	@Override
	public String toString() {
		return "Product [id=" + id + ", name=" + name + ", price=" + price + "]";
	}

}

<?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="com.how2java.pojo">
		<resultMap type="Product" id="productBean">
			<id column="pid" property="id" />
			<result column="pname" property="name" />
			<result column="price" property="price" />
	
			<!-- 多对一的关系 -->
			<!-- property: 指的是属性名称, javaType：指的是属性的类型 -->
			<association property="category" javaType="Category">
				<id column="cid" property="id"/>
				<result column="cname" property="name"/>
			</association>
		</resultMap>
	
		<!-- 根据id查询Product, 关联将Orders查询出来 -->
		<select id="listProduct" resultMap="productBean">
			select c.*, p.*, c.id 'cid', p.id 'pid', c.name 'cname', p.name 'pname' from category_ c left join product_ p on c.id = p.cid
		</select>    
	</mapper>

<?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>
	  <package name="com.how2java.pojo"/>
	</typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
			<property name="driver" value="com.mysql.jdbc.Driver"/>
			<property name="url" value="jdbc:mysql://localhost:3306/how2java?characterEncoding=UTF-8"/>
			<property name="username" value="root"/>
			<property name="password" value="admin"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/how2java/pojo/Category.xml"/>
        <mapper resource="com/how2java/pojo/Product.xml"/>
    </mappers>
</configuration>

package com.how2java;
 
import java.io.IOException;
import java.io.InputStream;
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 com.how2java.pojo.Product;
 
public class TestMybatis {
 
    public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
 
        List<Product> ps = session.selectList("listProduct");
        for (Product p : ps) {
			System.out.println(p+" 对应的分类是 \t "+ p.getCategory());
		}

        session.commit();
        session.close();
 
    }
}