MyBatis高级查询 一对一映射
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drop database if exists simple; create database simple; use simple; drop table if exists sys_user; create table sys_user ( id bigint not null auto_increment comment \'用户ID\', user_name varchar(50) comment \'用户名\', user_password varchar(50) comment \'密码\', user_email varchar(50) comment \'邮箱\', user_info text comment \'简介\', head_img blob comment \'头像\', create_time datetime comment \'创建时间\', primary key (id) ); alter table sys_user comment \'用户表\'; drop table if exists sys_role; create table sys_role( id bigint not null auto_increment comment \'角色ID\', role_name varchar(50) comment \'角色名\', enabled int comment \'有效标志\', create_by bigint comment \'创建人\', create_time datetime comment \'创建时间\', primary key (id) ); alter table sys_role comment \'角色表\'; drop table if exists sys_privilege; create table sys_privilege ( id bigint not null auto_increment comment \'权限ID\', privilege_name varchar(50) comment \'权限名称\', privilege_url varchar(50) comment \'权限URL\', primary key (id) ); alter table sys_privilege comment \'权限表\'; drop table if exists sys_user_role; create table sys_user_role ( user_id bigint comment \'用户ID\', role_id bigint comment \'角色ID\' ); alter table sys_user_role comment \'用户角色关联表\'; drop table if exists sys_role_privilege; create table sys_role_privilege ( role_id bigint comment \'用户ID\', privilege_id bigint comment \'角色ID\' ); alter table sys_role_privilege comment \'角色权限关联表\';
假如1个用户只能有1种角色sys_user和sys_role是通过sys_user_role一对一关联；
1.使用自动映射处理一对一关系；优点：当一定会使用到嵌套结果时使用。
1.在SysUser.class model中增加SysRole的对象。
private SysRole role;
2.在查询的xml Mapper文件中对查询出的role属性写出对应的属性名称。
<select id="selectUserAndById" resultType="test.model.SysUser"> select u.id, u.user_name userName, u.user_password userPassword, u.user_email userEmail, u.create_time createTime, u.user_info userInfo, u.head_img headImg, r.id "role.id", r.role_name "role.roleName", r.enabled "role.enabled", r.create_by "role.createBy", r.create_time "role.createTime" from sys_user u inner join sys_user_role ur on u.id=ur.user_id inner join sys_role r on ur.user_id=r.id where u.id=#{id} </select>
2.使用resultMap配置一对一映射
<?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="test.dao.SysUserMapper"> <resultMap id="BaseResultMap" type="test.model.SysUser"> <!-- WARNING - @mbggenerated This element is automatically generated by MyBatis Generator, do not modify. --> <id column="id" jdbcType="BIGINT" property="id" /> <result column="user_name" jdbcType="VARCHAR" property="userName" /> <result column="user_password" jdbcType="VARCHAR" property="userPassword" /> <result column="user_email" jdbcType="VARCHAR" property="userEmail" /> <result column="create_time" jdbcType="TIMESTAMP" property="createTime" /> <result column="user_info" jdbcType="LONGVARCHAR" property="userInfo" /> <result column="head_img" jdbcType="LONGVARBINARY" property="headImg" /> </resultMap> <resultMap type="test.model.SysUser" id="userRoleResultMap" extends="BaseResultMap"> <!-- role相关属性 --> <result column="role_id" jdbcType="BIGINT" property="role.id" /> <result column="role_name" jdbcType="VARCHAR" property="role.roleName" /> <result column="enabled" jdbcType="INTEGER" property="role.enabled" /> <result column="create_by" jdbcType="BIGINT" property="role.createBy" /> <result column="role_create_time" jdbcType="TIMESTAMP" property="role.createTime" /> </resultMap>
<!-- 注意返回 resultMap="userRoleResultMap"--> <select id="selectUserAndById" resultMap="userRoleResultMap"> select u.id, u.user_name, u.user_password, u.user_email, u.create_time, u.user_info, u.head_img, r.id role_id, r.role_name role_name, r.enabled enabled, r.create_by create_by, r.create_time role_create_time from sys_user u inner join sys_user_role ur on u.id=ur.user_id inner join sys_role r on ur.user_id=r.id where u.id=#{id} </select> </mapper>
3.使用resultMap的associaction标签配置一对一映射
<?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="test.dao.SysUserMapper"> <resultMap id="BaseResultMap" type="test.model.SysUser"> <!-- WARNING - @mbggenerated This element is automatically generated by MyBatis Generator, do not modify. --> <id column="id" jdbcType="BIGINT" property="id" /> <result column="user_name" jdbcType="VARCHAR" property="userName" /> <result column="user_password" jdbcType="VARCHAR" property="userPassword" /> <result column="user_email" jdbcType="VARCHAR" property="userEmail" /> <result column="create_time" jdbcType="TIMESTAMP" property="createTime" /> <result column="user_info" jdbcType="LONGVARCHAR" property="userInfo" /> <result column="head_img" jdbcType="LONGVARBINARY" property="headImg" /> </resultMap> <!-- 继承上面的UserResultMap --> <resultMap type="test.model.SysUser" id="userRoleResultMap" extends="BaseResultMap"> <!-- role相关属性 --> <!-- 对应的ResultMap在test.dao.SysRoleMapper这个命名控件中--> <association property="role" columnPrefix="role_" resultMap="test.dao.SysRoleMapper.BaseResultMap"></association> </resultMap> <select id="selectUserAndById" resultMap="userRoleResultMap"> select u.id, u.user_name, u.user_password, u.user_email, u.create_time, u.user_info, u.head_img, r.id role_id, r.role_name role_role_name, r.enabled role_enabled, r.create_by role_create_by, r.create_time role_create_time from sys_user u inner join sys_user_role ur on u.id=ur.user_id inner join sys_role r on ur.user_id=r.id where u.id=#{id} </select> <mapper/>
<mapper namespace="test.dao.SysRoleMapper"> <resultMap id="BaseResultMap" type="test.model.SysRole"> <!-- WARNING - @mbggenerated This element is automatically generated by MyBatis Generator, do not modify. --> <id column="id" jdbcType="BIGINT" property="id" /> <result column="role_name" jdbcType="VARCHAR" property="roleName" /> <result column="enabled" jdbcType="INTEGER" property="enabled" /> <result column="create_by" jdbcType="BIGINT" property="createBy" /> <result column="create_time" jdbcType="TIMESTAMP" property="createTime" /> </resultMap> </mapper>
4.association标签的嵌套查询 （子查询）
fetchType="lazy"；还需要在配置文件中加
<settings> <setting name="logImpl" value="LOG4J"/>
<setting name="aggressiveLazyLoading" value="false"/> </settings>
<!-- SysUserMapper.xml -->
<?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="test.dao.SysUserMapper"> <resultMap id="BaseResultMap" type="test.model.SysUser"> <!-- WARNING - @mbggenerated This element is automatically generated by MyBatis Generator, do not modify. --> <id column="id" jdbcType="BIGINT" property="id" /> <result column="user_name" jdbcType="VARCHAR" property="userName" /> <result column="user_password" jdbcType="VARCHAR" property="userPassword" /> <result column="user_email" jdbcType="VARCHAR" property="userEmail" /> <result column="create_time" jdbcType="TIMESTAMP" property="createTime" /> <result column="user_info" jdbcType="LONGVARCHAR" property="userInfo" /> <result column="head_img" jdbcType="LONGVARBINARY" property="headImg" /> </resultMap> <!-- 继承上面的UserResultMap --> <resultMap type="test.model.SysUser" id="userRoleResultMap" extends="BaseResultMap"> <!-- role相关属性 --> <!-- 对应的ResultMap在test.dao.SysRoleMapper这个命名控件中 注意这里没有resultMap="" --> <association property="role" column="{id=role_id}" fetchType="lazy" select="test.dao.SysRoleMapper.selectRoleById"></association> </resultMap> <select id="selectUserAndById" resultMap="userRoleResultMap"> select u.id, u.user_name, u.user_password, u.user_email, u.create_time, u.user_info, u.head_img, ur.role_id from sys_user u inner join sys_user_role ur on u.id=ur.user_id where u.id=#{id} </select> </mapper>
<!--- RoleMapper.xml -> <?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="test.dao.SysRoleMapper"> <resultMap id="BaseResultMap" type="test.model.SysRole"> <!-- WARNING - @mbggenerated This element is automatically generated by MyBatis Generator, do not modify. --> <id column="id" jdbcType="BIGINT" property="id" /> <result column="role_name" jdbcType="VARCHAR" property="roleName" /> <result column="enabled" jdbcType="INTEGER" property="enabled" /> <result column="create_by" jdbcType="BIGINT" property="createBy" /> <result column="create_time" jdbcType="TIMESTAMP" property="createTime" /> </resultMap> <select id="selectRoleById" resultMap="BaseResultMap"> select * from sys_role where id=#{id} </select> </mapper>
测试不能用debug看效果；
单元测试
package com.watermelon.test; import org.apache.ibatis.session.SqlSession; import org.junit.Assert; import org.junit.Test; import test.dao.SysUserMapper; import test.model.SysUser; public class SysUserMappertest extends BaseMapperTest{ @Test public void testSelectUserAndById() { SqlSession sqlSession = getSqlSession(); SysUserMapper sysUserMapper = sqlSession.getMapper(SysUserMapper.class); SysUser user = sysUserMapper.selectUserAndById(1L); Assert.assertNotNull(user); System.out.println("调用user.getRole()"); Assert.assertNotNull(user.getRole()); } }
直接运行效果：
DEBUG [main] - ==> Preparing: select u.id, u.user_name, u.user_password, u.user_email, u.create_time, u.user_info, u.head_img, ur.role_id from sys_user u inner join sys_user_role ur on u.id=ur.user_id where u.id=? DEBUG [main] - ==> Parameters: 1(Long) TRACE [main] - <== Columns: id, user_name, user_password, user_email, create_time, user_info, head_img, role_id TRACE [main] - <== Row: 1, admin, 123456, admin@mybats.tk, 2017-09-25 15:55:15.0, <<BLOB>>, <<BLOB>>, 1 DEBUG [main] - <== Total: 1 调用user.getRole() DEBUG [main] - ==> Preparing: select * from sys_role where id=? DEBUG [main] - ==> Parameters: 1(Long) TRACE [main] - <== Columns: id, role_name, enabled, create_by, create_time TRACE [main] - <== Row: 1, 管理员, 1, 1, 2017-09-25 15:55:59.0 DEBUG [main] - <== Total: 1
debug效果：
注：虽然这个方法已经满足了我们的要求，但是有些时候还是需要在触发某些方法时将所有的数据都加载进来。
可以调用对象的“equals，clone，hashCode，toString”.等方法。
@Test public void testSelectUserAndById() { SqlSession sqlSession = getSqlSession(); SysUserMapper sysUserMapper = sqlSession.getMapper(SysUserMapper.class); SysUser user = sysUserMapper.selectUserAndById(1L); Assert.assertNotNull(user); // String s = ""; // s.equals(null); //上面不行，必须是返回对象的方法 user.equals(null); System.out.println("调用user.getRole()"); Assert.assertNotNull(user.getRole()); }
结果:
DEBUG [main] - ==> Preparing: select u.id, u.user_name, u.user_password, u.user_email, u.create_time, u.user_info, u.head_img, ur.role_id from sys_user u inner join sys_user_role ur on u.id=ur.user_id where u.id=? DEBUG [main] - ==> Parameters: 1(Long) TRACE [main] - <== Columns: id, user_name, user_password, user_email, create_time, user_info, head_img, role_id TRACE [main] - <== Row: 1, admin, 123456, admin@mybats.tk, 2017-09-25 15:55:15.0, <<BLOB>>, <<BLOB>>, 1 DEBUG [main] - <== Total: 1 DEBUG [main] - ==> Preparing: select * from sys_role where id=? DEBUG [main] - ==> Parameters: 1(Long) TRACE [main] - <== Columns: id, role_name, enabled, create_by, create_time TRACE [main] - <== Row: 1, 管理员, 1, 1, 2017-09-25 15:55:59.0 DEBUG [main] - <== Total: 1 调用user.getRole()
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