mybatis最基本的使用

1.新建配置文件mybatis-config.xml(src/main/resources/mybatis-config.xml)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://192.168.2.46:3306/myserver" />
                <property name="username" value="admin" />
                <property name="password" value="00000000" />
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="UserMapper.xml" />
    </mappers>

</configuration>

2.在第1步的目录下，再建一个UserMapper.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="com.studyserver.module.login.mapper.UserMapper">
    <insert id="addUser">
        insert into user (phone, password)
        values (#{phone}, #{password})
    </insert>
    <insert id="addToken">
        insert into user_token (phone, token)
        values (#{phone}, #{token})
    </insert>
    <select id="findAll" resultType="com.studyserver.module.login.dto.UserDTO">
        select * from user
    </select>
</mapper>

3.pom.xml文件，引入

<dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus</artifactId>
            <version>3.5.0</version>
 </dependency>
 <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.27</version>
 </dependency>

4.在具体使用的地方添加接口

截屏2022-01-18 上午11.27.03.png

5.在controller中，获取SqlSession

private SqlSession getSqlSession() throws Exception {
        String config = "mybatis-config.xml";
        // 这里的Resources是org.apache.ibatis.io.Resources
        InputStream inputStream = Resources.getResourceAsStream(config);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        return sqlSession;
    }

6.用mapper调用方法，查询数据

UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<UserDTO> all = mapper.findAll();
        
        for (int i = 0; i < all.size(); i++) {
            UserDTO o = all.get(i);
            if (o.getPhone().equals(registerDTO.getPhone())) {
                // 用户已经存在
                return RestResponse.build(CommonResponseCode.DATA_EXISTS);
            }
        }

all就是查询出来的结果集
7.操作完之后，需要提交session事务

sqlSession.commit();
sqlSession.close();