Spring Boot + Mybatis 完成数据查询

引入依赖

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.1</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

mybatis-spring-boot-starter版本需要与spring boot 的版本一致（不同的mybatis的start对应的springboot的版本都是不完全一致的）

properties里进行数据库连接配置

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/imooc?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=GMT
spring.datasource.username=root
spring.datasource.password=123456

数据库建表

create table students
(
    id   int auto_increment primary key,
    name varchar(23) not null
);
insert into students (id, name) values (1, '小明');
insert into students (id, name) values (2, '小红');

新建实体类

public class Student {
    private int id;
    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

新建Mapper对象操作数据库（这里是用的interface接口！！）

/**
 * 新建Mapper对象操作数据库
 */
@Mapper
@Repository
public interface StudentMapper {
    @Select("select * from students where id=#{id}")
    Student findById(int id);
}

新建service类

/**
 * 学生service
 */
@Service
public class StudentService {
    @Autowired
    StudentMapper studentMapper;

    public Student findStudent(int id) {
        return studentMapper.findById(id);
    }
}

新建controller层

@RestController
public class StudentController {
    @Autowired
    StudentService studentService;

    @GetMapping("/student")
    public Map findStudent(@RequestParam int num) {
        HashMap<Object, Object> result = new HashMap<>();

        Student student = studentService.findStudent(num);
        result.put("data", student);
        result.put("msg", "Successful");
        result.put("code", 0);

        return result;
    }
}

output

{
  "msg": "Successful",
  "code": 0,
  "data": {
    "id": 1,
    "name": "小明"
  }
}