idea创建springboot简单查询数据库查询案例

完整代码下载地址：https://download.csdn.net/download/qq_37231511/12028858或

 

1.创建数据库mybatis_01,并建表user,插入一条数据，如图

2.创建springboot项目

点击next, 设置项目名称

点击next,选择需要用的框架，spring web、 mybatis、mysqlDriver

点击next,点击finish即创建成功，如图

3.整合MBG插件，自动生成实体类与mapper文件，MBG插件配置可见博文：https://blog.csdn.net/qq_37231511/article/details/103510314

4.配置application.properties

#mysql
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/mybatis_01?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf-8
spring.datasource.username=root
spring.datasource.password=root
#dao
#与文件目录一致
mybatis.type-aliases-package==com.xue.demo1.repository.dao
mybatis.mapper-locations=classpath*:com/xue/demo1/repository/mapper/*.xml

5.在pom.xml中build中配置资源，因为mapper.xml文件没有放置到src-main-resources下面，是不会被maven build plugin给默认扫描到的

<resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.xml</include>
                <include>**/*.properties</include>
            </includes>
            <filtering>true</filtering>
        </resource>
        </resources>

6. 创建controller包，并创建类UserController

package com.xue.demo1.controller;

import com.xue.demo1.entity.User;
import com.xue.demo1.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {

    @Autowired
    private UserService userService;
    @RequestMapping("/user")
    public User getUser(){
        User user = userService.getUser(1);

        if (null != user){
            return user;
        }else {

            return null;

        }


    }
}

7.创建service层创建接口UserService与接口实现类UserServiceImpl

UserService

package com.xue.demo1.service;

import com.xue.demo1.entity.User;

public interface UserService {

    public User getUser(Integer id);
}

UserServiceImpl

package com.xue.demo1.service.impl;

import com.xue.demo1.entity.User;
import com.xue.demo1.repository.dao.UserMapper;
import com.xue.demo1.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;
    @Override
    public User getUser(Integer id) {

        User user = userMapper.selectByPrimaryKey(id);

        if(null != user){
            return user;
        }else {
            return null;
        }
    }
}

 8.至此代码编写完成，项目结构如图

9.运行项目，在浏览器输入localhost:8080/user，如图