1.创立我的项目导入依赖

<!--mybatis--><dependency>    <groupId>org.mybatis.spring.boot</groupId>    <artifactId>mybatis-spring-boot-starter</artifactId>    <version>2.1.4</version></dependency><!--mysql--><dependency>    <groupId>mysql</groupId>    <artifactId>mysql-connector-java</artifactId>    <scope>runtime</scope></dependency>

2.配置文件

application.properties配置文件中连贯数据库

spring.datasource.url=jdbc:mysql://localhost:3306/tedu_ums?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=Asia/Shanghaispring.datasource.username=rootspring.datasource.password=root

3.创立UserMapper接口

在Mybatis01Application启动类所在包下创立子包mapper,并在子包中创立咱们的UserMapper接口

4.交给spring去治理

把咱们的UserMapper交给Spring去治理,通过咱们的@Mapper,把咱们的接口交给Spring去治理

5.编写sql语句

5.1通过注解形式编写sql

UserMapper接口中写一个形象办法,并且在办法上通过注解写一个SQL语句

@Mapperpublic interface UserMapper {    @Select("select username from user where id = #{id}")    String findUsernameById(int id);}

5.2通过xml形式编写sql

UserMappr.java 接口
@Mapperpublic interface UserMapper {    /**     * 通过id查找对弈的 User 对象     * @return     */    User findUserById(Integer id);}
UserMappr.xml 配置文件
<?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="cn.tedu.mybatis01.mapper.UserMapper">    <select id="findUserById" resultType="cn.tedu.mybatis01.entity.User">        select * from t_user where id = #{id}    </select></mapper>
application.properties 配置文件
mybatis.mapper-locations=classpath:mapper/*.xml

6.测试

在test包下创立一个测试类,并且在测试类上必须增加一个@SpringBootTest注解,在测试类中写一个测试方法,测试方法上增加一个@Test注解
注入咱们UserMapper对象,并调用咱们曾经写好的UserMapper里的findUsernameById(int id)办法与 findUserById(int id)

@SpringBootTestpublic class UserMapperTests {~~~~    @Autowired UserMapper userMapper;    @Test void testFindById(){        String username = userMapper.findUsernameById(1);        System.out.println(username);    }        @Test void testFindUserById(){        User user = userMapper.findUserById(1);        System.out.println(user);    }}

注意事项

在xml配置文件中写sql语句,namespace所对应的UserMapper.java的全路径名,具体方法对应的sql语句中的id为对应的办法名称