闲来无事，写个mybatis-plus的流程

导包，版本什么的我就不说了
第一步：写yml文件
给个端口号
server:
port: 8081
给个数据源
spring:
datasource:
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://192.168.47.130:3306/mybatis_plus?serverTimezone=GMT%2B8&characterEncoding=utf-8
username: root
password: 123456
配mybatisplus驼峰和映射位置
mybatis-plus:
configuration:
map-underscore-to-camel-case: true
mapper-locations: classpath:mapper 继承IService泛型实体类 public interface UserService extends IService { }

第七步：service实现类
package com.lindashua.mybatisplus.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.lindashua.mybatisplus.entity.User;
import com.lindashua.mybatisplus.mapper.UserMapper;
import com.lindashua.mybatisplus.service.UserService;
import org.springframework.stereotype.Service;
注解开启通用Service
@Service
实现UserService 并继承ServiceImpl泛型mapper和实体类
public class UserServiceImpl extends ServiceImpl implements UserService {
}

第八步：UserMapper.xml
这个是为了实现自定义mapper，就和mybatis一样写就可以




select * from user
where name like “%”#{name}"%"

第九步：测试类
这里提醒一下，测试类要和我们的启动类在一个位置上，不然注解读不到spring配置

package com.lindashua.mybatisplus;

import com.lindashua.mybatisplus.entity.User;
import com.lindashua.mybatisplus.mapper.UserMapper;
import com.lindashua.mybatisplus.service.UserService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;


import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


@SpringBootTest
public class MybatisPlusTest {

    @Autowired
    private UserMapper userMapper;

    @Autowired
    private UserService userService;

    @Test
    public void test1(){
        System.out.println("1");
    }

    @Test
    public void FindById(){
        Object o = userMapper.selectById(1l);
        System.out.println(o);
    }

    @Test
    public void selectAllUseLike(){
        List userList = userMapper.selectAllUseLike("j");
        for (User user : userList) {
            System.out.println(user);
        }
    }

    @Test
    public void FindByBatchIds(){
        List users = userMapper.selectBatchIds(Arrays.asList(1, 2, 3));
        for (User user : users) {
            System.out.println(user);
        }
    }

    @Test
    public void CountAll(){
        int count = userService.count();
        System.out.println(count);
    }

    @Test
    public void InsertBatch(){
        List userList = new ArrayList<>();

        for (int i = 0; i < 10; i++) {
            User user = new User();
            user.setAge(i);
            user.setName("clone"+i);
            userList.add(user);
        }

        userService.saveBatch(userList);
    }

    @Test
    public void UpdateFill(){
        User user = new User();
        user.setId(55l);
        user.setAge(100);
        userService.updateById(user);
    }
}

这样一套拥有自增ID，自动填充创建及修改日期，且支持自定义sql的MQ程序基本功能就完成了

总结：自动填充需要重写metaObjectHandler方法insertFill和updateFill
this.strictInsertFill(metaObject, “updateTime”, LocalDateTime.class, LocalDateTime.now());
乐观锁和分页需要增加配置类，创建一个bean增强MybatisPlusInterceptor对象， mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());，开启分页或者乐观锁