总结 MyBatis 的XML实现方法

目次
1 设置毗连字符串和MyBatis
2 写长期层代码
2.1 添加mapper接⼝
3 增编削查利用 
3.1 增(Insert)
3.2 删(Delete) 
3.3 改(Update) 
3.4 查(Select) 

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MyBatis XML的⽅式须要以下两步:
设置数据库毗连字符串和MyBatis
写长期层代码
1 设置毗连字符串和MyBatis

此步调须要进⾏两项设置，数据库毗连字符串设置和MyBatis的XML⽂件设置。
假如是application.yml⽂件,设置内容如下:

2 写长期层代码

长期层代码分两部分
1. ⽅法界说Interface
2. ⽅法实现:XXX.xml

2.1 添加mapper接⼝

数据长期层的接⼝界说：

1. import com.example.demo.model.UserInfo;
2. import org.apache.ibatis.annotations.Mapper;
3. import java.util.List;
4. @Mapper
5. public interface UserInfoXMlMapper {
6.      List<UserInfo> queryAllUser();
7. }

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2.2 添加UserInfoXMLMapper.xml

1. <?xml version="1.0" encoding="UTF-8"?>
2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
3.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
4. <mapper namespace="org.example.mybatisdemo.mapper.UserInfoXMLMapper">
5.    
6. </mapper>

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创建UserInfoXMLMapper.xml,路径参考yml中的设置

 
查询全部⽤⼾的具体实现：

1. <?xml version="1.0" encoding="UTF-8"?>
2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
3. "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
4. <mapper namespace="com.example.demo.mapper.UserInfoXMlMapper">
5.      <select id="queryAllUser" resultType="com.example.demo.model.UserInfo">
6.          select username,`password`, age, gender, phone from userinfo
7.      </select>
8. </mapper>

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2.3 单元测试 

1. @SpringBootTest
2. class UserInfoMapperTest {
3.      @Autowired
4.      private UserInfoMapper userInfoMapper;
5.      @Test
6.      void queryAllUser() {
7.      List<UserInfo> userInfoList = userInfoMapper.queryAllUser();
8.          System.out.println(userInfoList);
9.      }
10. }

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3 增编削查利用 

3.1 增(Insert)

UserInfoMapper接⼝:

1. Integer insertUser(UserInfo userInfo);

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UserInfoMapper.xml实现:

1. <insert id="insertUser">
2.      insert into userinfo (username, `password`, age, gender, phone) values (#
3. {username}, #{password}, #{age},#{gender},#{phone})
4. </insert>

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假如使⽤@Param设置参数名称的话,使⽤⽅法和注解类似
UserInfoMapper接⼝:

1. Integer insertUser(@Param("userinfo") UserInfo userInfo);

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UserInfoMapper.xml实现:

1. <insert id="insertUser">
2. insert into userinfo (username, `password`, age, gender, phone) values
3. (#{userinfo.username},#{userinfo.password},#{userinfo.age},#
4. {userinfo.gender},#{userinfo.phone})
5. </insert>

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返回⾃增id
接⼝界说稳固,Mapper.xml实现设置useGeneratedKeys和keyProperty属性.

1. <insert id="insertUser" useGeneratedKeys="true" keyProperty="id">
2. insert into userinfo (username, `password`, age, gender, phone) values
3. (#{userinfo.username},#{userinfo.password},#{userinfo.age},#
4. {userinfo.gender},#{userinfo.phone})
5. </insert>

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3.2 删(Delete) 

UserInfoMapper接⼝:

1. Integer deleteUser(Integer id);

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 UserInfoMapper.xml实现:

1. <delete id="deleteUser">
2. delete from userinfo where id = #{id}
3. </delete>

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3.3 改(Update) 

UserInfoMapper接⼝:

1. Integer updateUser(UserInfo userInfo);

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UserInfoMapper.xml实现:

1. <update id="updateUser">
2. update userinfo set username=#{username} where id=#{id}
3. </update>

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3.4 查(Select) 

同样的,使⽤XML的⽅式进⾏查询,也存在数据封装的题目 我们把SQL语句进⾏简单修改,查询更多的字段内容.

1. <select id="queryAllUser" resultType="com.example.demo.model.UserInfo">
2. select id, username,`password`, age, gender, phone, delete_flag,
3. create_time, update_time from userinfo
4. </select>

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 结果显⽰:deleteFlag,createTime,updateTime也没有进⾏赋值.
办理办法和注解类似:
1. 起别名
2. 结果映射
3. 开启驼峰定名
此中1,3的办理办法和注解⼀样,不再多说,接下来看下xml假如来写结果映射
Mapper.xml

1. <resultMap id="XmlBaseMap" type="com.example.demo.model.UserInfo">
2. <id column="id" property="id"></id>
3.      <result column="delete_flag" property="deleteFlag"></result>
4.      <result column="create_time" property="createTime"></result>
5.      <result column="update_time" property="updateTime"></result>
6. </resultMap>
7. <select id="queryAllUser" resultMap="XmlBaseMap">
8.      select id, username,`password`, age, gender, phone, delete_flag,
9.   create_time, update_time from userinfo
10. </select>

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