用户故事

首先，MyBatis为您生成模型、Map器和mapper.xml。
现在，如果您有两个模型-用户和角色
用户和角色之间的关系是什么？
一个用户有多个角色，一个角色可以授权给多个用户，所以他们是many-to-many关系。

如何实施？

• 将列表角色添加到用户模型

private List<Role> roles = new ArrayList<>();

• 将列表用户添加到角色模型

private List<User> users = new ArrayList<>();

• 创建UserRoleMapper接口以添加一些方法

package com.jim.mapper;

  import com.jim.model.Role;
  import com.jim.model.User;

  import java.util.List;

  public interface UserRoleMapper {
      int deleteRole(long userId, long roleId);
      int addRole(long userId, long roleId);
      List<Role> getRoles(long userId);
      List<User> getUsers(long roleId);
  }

• 添加一个xml到MapSQL & result。

<resultMap id="UserResultMap" type="com.jim.model.Role">
      <id column="id" jdbcType="INTEGER" property="id"/>
      <result column="name" jdbcType="VARCHAR" property="name"/>
      <collection javaType="ArrayList" property="users" resultMap="RoleResultMap" />
  </resultMap>

  <resultMap id="RoleResultMap" type="com.jim.model.User">
      <id column="id" jdbcType="BIGINT" property="id"/>
      <result column="username" jdbcType="VARCHAR" property="username"/>
      <collection javaType="ArrayList" property="roles" resultMap="UserResultMap" />
  </resultMap>

  <insert id="addRole">
      INSERT INTO user_role (userId, roleId)
      VALUES (#{userId, jdbcType=BIGINT}, #{roleId, jdbcType=BIGINT});
  </insert>
  <delete id="deleteRole" >
      DELETE FROM user_role
      WHERE 1=1
      AND userId=#{userId}
      AND roleId=#{roleId}
  </delete>

  <select id="getRoles" resultMap="UserResultMap">
      SELECT
      r.id AS id, r.name AS name
      FROM users AS  u
      LEFT JOIN user_role AS ur ON u.id = ur.userId
      LEFT JOIN roles AS r ON r.id = ur.roleId
      WHERE 1=1
        AND u.id = #{id,jdbcType=BIGINT}
        AND r.isActive = 1
        AND u.isActive = 1
  </select>

  <select id="getUsers" resultMap="RoleResultMap">
      SELECT
      u.id AS id, u.username AS username
      FROM roles AS  r
      LEFT JOIN user_role AS ur ON r.id = ur.roleId
      LEFT JOIN users AS u ON u.id = ur.userId
      WHERE 1=1
      AND r.id = #{id,jdbcType=BIGINT}
      AND r.isActive = 1
      AND u.isActive = 1
  </select>

请看一下文档中的嵌套Resultmaps部分。
这应通过类似于以下内容的结果图来实现

<resultMap id="xx" type="map"> 
    <association id="key1" javaType="bean1" /> 
    <collection id="key2" ofType="bean2" /> 
</resultMap>

大家可以看看我的repository里面有一个例子。