1. springboot整合mybatis

1. pom.xml

	
        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            2.2.0
        

1. 实体类

@Data
public class User {

    @Id
    private String username;
    private String password;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

2. UserMapper

@Mapper
public interface UserMapper {

    public User getUser(String username);
}

3. UserService

@Service
public class UserService {

    @Autowired
    UserMapper userMapper;

    public User getUserByName(String username){
        return userMapper.getUser(username);
    }
}

1. 创建配置文件mybatis-config.xml，从 XML 中构建 SqlSessionFactory这里可以参考官网的说明 https://mybatis.org/mybatis-3/zh/getting-started.html.

2. 创建UserMapper.xml，探究已映射的 SQL 语句

    
        select * from User where username = #{username}
    

3. 配置mybatis规则，application.yaml

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT%2B8
    # url=jdbc:mysql://localhost:3306/book?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT
    username: root
    password: 2550
    driver-class-name: com.mysql.cj.jdbc.Driver
# 配置mybatis规则
mybatis:
  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations: classpath:mybatis/mapper/*.xml

	@ResponseBody
    @GetMapping("/user")
    public User getUserByName(@RequestParam("username") String username) {
        return userService.getUserByName(username);
    }

添加依赖 参考第二步

1. 创建一张表
   
2. 创建实体类City

@Data
public class City {

    private Long id;
    private String name;
    private String state;
    private String country;
}

3. 创建CityMapper

@Mapper
public interface CityMapper {

    @Select("select * from city where id = #{id} ")
    public City getById(Long id);
}

1. 创建CityService

@Service
public class CityService {

    @Autowired
    CityMapper cityMapper;

    public City getCityById(Long id) {
        return cityMapper.getById(id);
    }
}

2. 测试方法

	@Autowired
    CityService cityService;

    @ResponseBody
    @GetMapping("/city")
    public City getCityById(@RequestParam("id")Long id) {
        return cityService.getCityById(id);
    }

3. 测试