整合mybatis

整合包

<dependency>
    <groupId>org.mybatis.spring.bootgroupId>
    <artifactId>mybatis-spring-boot-starterartifactId>
    <version>2.2.2version>
dependency>

配置文件:

application.properties

#整合mybatis
#别名
mybatis.type-aliases-package=com.ljm.pojo
#注册mapper
#classpath代表资源目录(resources)
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml

各种层

mybatis配置:

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.ljm.mapper.UserMapper">



    <select id="queryUserList" resultType="user" >
        select * from mybatis.user
    select>
mapper>

mapper(DAO)

@Mapper
@Repository 
public interface UserMapper {

    List queryUserList();
}

//Repository用来表明该类是用来执行与数据库相关的操作（即dao对象），并支持自动处理数据库操作产生的异常
//@Mapper 表示这是一个mybatis的mapper类  注册

service

import com.ljm.pojo.User;
import java.util.List;


public interface UserService {
    List queryUserList();
}

//-------------------
import java.util.List;
@Service
public class UserServiceImpl implements UserService{

    @Autowired
    private UserMapper userMapper;

    @Override
    public List queryUserList() {
        return userMapper.queryUserList();
    }
}

controller  调service层

@RestController
public class UserController {

    @Autowired
    private UserServiceImpl userService;  //实现类
//    private UserService userService;   //接口   两个测试都可以,有什么区别

    @GetMapping("/qu")
    public  List queryUserList(){
        List userList = userService.queryUserList();
        return userList;
    }
}