[Java知识库]Mybatis-plus的Service

Service

1、通用Service接口

可以看官网的CRUD接口

https://baomidou.com/pages/49cc81/

在example包下创建接口service.UserService

package com.example.service.service;

import com.baomidou.mybatisplus.extension.service.IService;
import com.example.pojo.User;

public interface UserService extends IService<User> {
}

在service包下创建文件impl.UserServiceImpl

@Service
package com.example.service.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.mapper.UserMapper;
import com.example.pojo.User;
import com.example.service.service.UserService;

public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {

}

ServiceImpl<UserMapper, User> 
UserMapper:自己创建的接口类
User:自己创建的实体类

2、测试通用Service之查询总记录数

创建测试文件

package com.example.mybatisplus;

import com.example.service.service.UserService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
public class MybatisPlusServiceTest {
    @Autowired
    private UserService userService;

    @Test
    public void test1(){
    	//查询总记录数
        //SELECT COUNT( * ) FROM user
        long count = userService.count();
        System.out.println("总结记录数:"+count);
    }
}

3、测试通用Service之批量添加功能

如果用BaseMapper的基本insert添加数据，如果以后有几千行甚至几万行数据需要添加，需要多少代码？这时候需要这个通用接口来实现

public void testInsertMore(){
        //INSERT INTO user ( id, name, age ) VALUES ( ?, ?, ? )
        List<User> list=new ArrayList<>();
        for (int i = 0; i <=10; i++) {
            User user=new User();
            user.setName("lisi"+i);
            user.setAge(20+i);
            list.add(user);
        }
        boolean b = userService.saveBatch(list);
        System.out.println(b);
    }