关于mybatis中mapper文件resultMap中collection的使用

 1 package com.mrlu.mybatis.domain;
 2 
 3 import java.util.List;
 4 
 5 /**
 6  * Created by stefan on 15-12-31.
 7  */
 8 public class User {
 9     private Integer id;
10     private String name;
11     private List<Account> accounts;
12 
13     public Integer getId() {
14         return id;
15     }
16 
17     public void setId(Integer id) {
18         this.id = id;
19     }
20 
21     public String getName() {
22         return name;
23     }
24 
25     public void setName(String name) {
26         this.name = name;
27     }
28 
29     @Override
30     public String toString() {
31         return "User{" +
32                 "id=" + id +
33                 ", name=‘" + name + ‘\‘‘ +
34                 ", accounts=" + accounts +
35                 ‘}‘;
36     }
37 
38     public List<Account> getAccounts() {
39         return accounts;
40     }
41 
42     public void setAccounts(List<Account> accounts) {
43         this.accounts = accounts;
44     }
45 
46 }

package com.mrlu.mybatis.domain;

/**
 * Created by stefan on 15-12-31.
 */
public class Account {
    private Integer id;
    private Integer userId;
    private String num;

    public Integer getId() {
        return id;
    }

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

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public String getNum() {
        return num;
    }

    public void setNum(String num) {
        this.num = num;
    }

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", userId=" + userId +
                ", num=‘" + num + ‘\‘‘ +
                ‘}‘;
    }
}

package com.mrlu.mybatis.dao;

import com.mrlu.mybatis.domain.User;

import java.util.List;

/**
 * Created by stefan on 15-12-31.
 */
public interface UserDao {
    public void insert(User user);

    public List<User> selectAll();
}

package com.mrlu.mybatis.dao;

import com.mrlu.mybatis.domain.Account;

/**
 * Created by stefan on 15-12-31.
 */
public interface AccountDao {
    public void insert(Account account);
}

<?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.mrlu.mybatis.dao.AccountDao" >
       <insert id="insert" useGeneratedKeys="true" keyProperty="id">
              INSERT INTO account(user_id, num) VALUES(
                #{userId}, #{num}
              )
       </insert>
</mapper>

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
 3 <mapper namespace="com.mrlu.mybatis.dao.UserDao" >
 4        <resultMap id="BaseResultMap" type="com.mrlu.mybatis.domain.User">
 5               <result column="id" property="id" />
 6               <result column="name" property="name" />
 7               <collection property="accounts" ofType="com.mrlu.mybatis.domain.Account" javaType="java.util.ArrayList" resultMap="accountMap">
 8                      <result column="id" property="id" />
 9                      <result column="user_id" property="userId" />
10                      <result column="num" property="num" />
11               </collection>
12        </resultMap>
13        <resultMap id="accountMap" type="com.mrlu.mybatis.domain.Account">
14               <result column="id" property="id" />
15               <result column="user_id" property="userId" />
16               <result column="num" property="num" />
17        </resultMap>
18        <insert id="insert" keyProperty="id" useGeneratedKeys="true">
19               INSERT INTO user(name) VALUES(
20                #{name}
21               )
22        </insert>
23 
24        <select id="selectAll" resultMap="BaseResultMap">
25               SELECT a.id,a.user_id,a.num FROM user t
26               RIGHT JOIN account a ON t.id=a.user_id
27        </select>
28 </mapper>

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
 3 <mapper namespace="com.mrlu.mybatis.dao.UserDao" >
 4        <resultMap id="BaseResultMap" type="com.mrlu.mybatis.domain.User">
 5               <result column="id" property="id" />
 6               <result column="name" property="name" />
 7               <collection property="accounts" column="id" select="selectAccount">
 8                      <result column="id" property="id" />
 9                      <result column="user_id" property="userId" />
10                      <result column="num" property="num" />
11               </collection>
12        </resultMap>
13        <insert id="insert" keyProperty="id" useGeneratedKeys="true">
14               INSERT INTO user(name) VALUES(
15                #{name}
16               )
17        </insert>
18 
19        <select id="selectAll" resultMap="BaseResultMap">
20               SELECT * FROM user t
21        </select>
22 
23        <select id="selectAccount" resultType="com.mrlu.mybatis.domain.Account">
24               SELECT * FROM account
25               WHERE user_id = #{id}
26        </select>
27 </mapper>