两个实体类分别如下：User用户类和Goods商品类。一个用户对应多个商品（一对多） package com.leo.entity;import java.util.List;public class User {private Integer id;private String username;private Integer age;private String address;private ListG

两个实体类分别如下：User用户类和Goods商品类。一个用户对应多个商品（一对多）

package com.leo.entity;

import java.util.List;
public class User {
	private Integer id;
	private String username;
	private Integer age;
	private String address;
	private List goodsList;

	public List getGoodsList() {
	return goodsList;
	}
	public void setGoodsList(List goodsList) {
	this.goodsList = goodsList;
	}
	public Integer getId() {
	return id;
	}
	public void setId(Integer id) {
	this.id = id;
	}
	public String getUsername() {
	return username;
	}
	public void setUsername(String username) {
	this.username = username;
	}
	public Integer getAge() {
	return age;
	}
	public void setAge(Integer age) {
	this.age = age;
	}
	public String getAddress() {
	return address;
	}
	public void setAddress(String address) {
	this.address = address;
	}
	public User() {
	super();
	// TODO Auto-generated constructor stub
	}
	@Override
	public String toString() {
	return "User [id=" + id + ", username=" + username + ", age=" + age
	+ ", address=" + address + ", goodsList=" + goodsList + "]";
	}
	
	
	
	
	
}

package com.leo.entity;

public class Goods {
	private Integer id;
	private String goodsName;
	private Integer goodsNumber;
	private Integer user_id;
	
	
	
	public Integer getId() {
	return id;
	}
	public void setId(Integer id) {
	this.id = id;
	}
	public String getGoodsName() {
	return goodsName;
	}
	public void setGoodsName(String goodsName) {
	this.goodsName = goodsName;
	}
	public Integer getGoodsNumber() {
	return goodsNumber;
	}
	public void setGoodsNumber(Integer goodsNumber) {
	this.goodsNumber = goodsNumber;
	}
	public Integer getUser_id() {
	return user_id;
	}
	public void setUser_id(Integer user_id) {
	this.user_id = user_id;
	}
	
	
	
	
}

 
 
		
	
	
	
	
	
	
	
		
	
	 select 
	u.id as u_id,
	u.username,
	u.age, 
	u.address 
	from
	user u
	 where 
	u.id =${value};
	
	 

 

	 
	
	
	 SELECT id,goodsName,goodsNumber,user_id FROM Goods WHERE user_id = #{value}
	
	 

package com.leo.servlet;

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

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

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

import com.leo.entity.Goods;
import com.leo.entity.User;
import com.leo.mapper.GoodsDao;
import com.leo.mapper.UserDao;



/**
 * Servlet implementation class MybatisServlet
 */
@WebServlet("/MybatisServlet")
public class MybatisServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	InputStream is = Resources.getResourceAsStream("com/leo/resources/mybatis-config.xml");
	SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
	SqlSession session = factory.openSession();
	
//	UserDao ud = session.getMapper(UserDao.class);
	GoodsDao gd = session.getMapper(GoodsDao.class);

	List goodsList= gd.selectGoodsForUser(1);
	
//	User user = ud.getUserinfoById(1);	
//	System.out.println(user);
//	List goodsList = user.getGoodsList();
	for (Goods goods : goodsList) {
	System.out.println(goods.getId()+" "+ goods.getGoodsName()+" "+goods.getGoodsNumber()+ " "+ goods.getUser_id());
	}
	session.commit();
	session.close();
	
	}
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	doGet(request, response);
	
	}

}

下面用集合嵌套结果这种方式：

只需要改动UserDao.xml,且只是用这一个映射文件就可以完成

 
 
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	 select 
	u.id as u_id,
	u.username,
	u.age,
	u.address,
	g.id as g_id, 
	g.goodsName,
	g.goodsNumber,
	g.user_id
	 from
	user u
	inner join goods g on u.id = g.user_id
	 where 
	u.id =${value};
		
	 

希望可以帮到大家，有什么措辞不正确，希望得到指正，希望进步