MyBatis--基本实现

MyBatis

MyBatis 基本操作

1、引入依赖

    <dependencies>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.3</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
   <!--web-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.3.2.RELEASE</version>
        </dependency>
        <!--data log-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

    </dependencies>

2、配置

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&useSSL=true&serverTimezone=GMT%2B8
spring.datasource.username=root
spring.datasource.password=root

3、代码实现

@RestController
public class TestContoller {

    @Autowired
    UserMapper userMapper;


    @GetMapping("users")
    public List<User> testMybatis() {
        List<User> users = userMapper.selectUsers();
        System.out.println(users);
        return users;
    }
}

@SpringBootApplication
//如果用了@Mapper注解，则不需要加入@MapperScan
@MapperScan("com.kingja.springboot.mapper")
public class Application extends SpringBootServletInitializer {


    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }
}

@Data
public class User {
    private Long id;
    private String name;
}

采用注解方式

@Mapper
public interface UserMapper {

    @Select("select * from user")
    List<User> selectUsers();
}

采用xml方式进行操作

rescources下创建mapper/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.kingja.springboot.mapper.UserMapper">
    <resultMap id="BaseResultMap" type="com.kingja.springboot.entity.User">
        <id column="id" jdbcType="INTEGER" property="id"/>
        <result column="name" jdbcType="VARCHAR" property="name"/>
    </resultMap>

    <select id="findAll" resultMap="BaseResultMap">
        select * from user
    </select>
</mapper>

报错

2020-12-28 17:34:58.269 ERROR 10304 --- [nio-8085-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.kingja.springboot.mapper.UserMapper.findAll] with root cause

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.kingja.springboot.mapper.UserMapper.findAll

加入配置

mybatis.mapper-locations=classpath:mapper/*.xml