idea創建springboot簡單查詢數據庫查詢案例

完整代碼下載地址：https://download.csdn.net/download/qq_37231511/12028858或

 

1.創建數據庫mybatis_01,並建表user,插入一條數據，如圖

2.創建springboot項目

點擊next, 設置項目名稱

點擊next,選擇需要用的框架，spring web、 mybatis、mysqlDriver

點擊next,點擊finish即創建成功，如圖

3.整合MBG插件，自動生成實體類與mapper文件，MBG插件配置可見博文：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
#與文件目錄一致
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中配置資源，因爲mapper.xml文件沒有放置到src-main-resources下面，是不會被maven build plugin給默認掃描到的

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

6. 創建controller包，並創建類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.創建service層創建接口UserService與接口實現類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.至此代碼編寫完成，項目結構如圖

9.運行項目，在瀏覽器輸入localhost:8080/user，如圖