SpringBoot+mybatis plus 框架搭建

1、引入引用

<?xml version="1.0" encoding="UTF-8"?>

    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.6.2
         
    
    com.ymn
    mybatis003
    0.0.1-SNAPSHOT
    mybatis003
    mybatis003
    
        1.8
    
    
        
            org.springframework.boot
            spring-boot-starter
        

        
            org.springframework.boot
            spring-boot-starter-test
            test
        

        
            com.baomidou
            mybatis-plus-boot-starter
            3.4.3.4
        
        
        
            mysql
            mysql-connector-java
            runtime
        
        
            com.h2database
            h2
            runtime
        
        
            org.projectlombok
            lombok
            RELEASE
            compile
        
        
            junit
            junit
            4.13.1
            test
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
        
    

　　2、配置数据库连接地址

# DataSource Config
server:
  port: 8099
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatisplus02?autoRe
connect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=CONVERT_TO_NULL&useSSL=false&nullCatalogMeansCurrent=true
    username: root
    password: 545456546546

　3、创建mapper

@Component
public interface UserMapper  extends BaseMapper {


}

4、创建service访问

@Component
public interface UserMapper  extends BaseMapper {


}

5、单元测试测试

package com.ymn.mybatis003;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.ymn.mybatis003.entitys.User;
import com.ymn.mybatis003.mappers.UserMapper;
import com.ymn.mybatis003.services.UserService;
import org.junit.Assert;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;


import java.util.List;
//有了@RunWith(SpringRunner.class)这些类才能实例化到spring容器中，自动注入才能生效，
@RunWith(SpringRunner.class)
@SpringBootTest
class Mybatis003ApplicationTests {

    @Autowired
    private UserMapper userMapper;

    @Autowired
    private UserService userService;

    @Test
    public void testSelect() {
        System.out.println(("----- selectAll method test ------"));
        List userList = userMapper.selectList(null);
        //Assert.assertEquals(5, userList.size());
        userList.forEach(System.out::println);
        userList.get(0).setName("王五77");
        //Update name by id
        userMapper.updateById(userList.get(0));

        //query user by id
        User user = userMapper.selectById(4);
        System.out.println("编号为4的用户："+user.getName());

        //use wrapper query
        QueryWrapper  queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("id",5);
        User user5 = userMapper.selectOne(queryWrapper);
        System.out.println("第五名用户");
        System.out.println(user5);

        //query count
        QueryWrapper queryWrapper1 = new QueryWrapper<>();
        queryWrapper1.gt("age",10);
        Long count = userMapper.selectCount(queryWrapper1);
        System.out.println("大于10岁的用户数："+count);

        User user3 = userService.getById(1);
        System.out.println("使用service获取对象");
        System.out.println(user3);

        LambdaQueryWrapper lamadaQueryWrapper = new LambdaQueryWrapper<>();
        lamadaQueryWrapper.eq(User::getId,9);
        User user9 = userService.getOne(lamadaQueryWrapper);
        System.out.println("第九个用户的名称："+user9.getName());

    }



}


6、sql语句