CREATE TABLE user
(
    id BIGINT(20) NOT NULL COMMENT '主鍵ID',
    name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
    age INT(11) NULL DEFAULT NULL COMMENT '年齡',
    email VARCHAR(50) NULL DEFAULT NULL COMMENT '郵箱',
    PRIMARY KEY (id)
);

INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');

spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/mybatis_plus?userSSL=false&Unicode=true&CharacterEncoding=utf-8&serverTimezone=GMT%2B8
    driver-class-name: com.mysql.cj.jdbc.Driver

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.sxau</groupId>
    <artifactId>mybatis_plus</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mybatis_plus</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
<!--    mysql-connector-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
<!--        mybatis-plus-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.0</version>
        </dependency>
<!--        lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    //主鍵自增配合 數(shù)據(jù)庫(kù)主鍵自增使用
    @TableId(type = IdType.AUTO)
    private Long id;
    private String name;
    private int age;
    private String email;
}

package com.sxau.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.sxau.pojo.User;
import org.springframework.stereotype.Repository;
@Repository
public interface Usermapper extends BaseMapper<User> {
    //所有CRUD操作已經(jīng)完成
    //不需要一大堆的。xml配置文件
}

@MapperScan("com.sxau.mapper")

package com.sxau.mybatis_plus;
import com.baomidou.mybatisplus.annotation.IdType;
import com.sxau.mapper.Usermapper;
import com.sxau.pojo.User;
import org.junit.jupiter.api.Test;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.List;
@MapperScan("com.sxau.mapper")
@SpringBootTest
class MybatisPlusApplicationTests {
    @Autowired
    Usermapper usermapper;
    @Test
    void contextLoads() {
        List<User> users = usermapper.selectList(null);
        users.forEach(System.out::println);
    }
}

#mybatis-plus日志配置文件
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

public enum IdType {
    AUTO(0),//數(shù)據(jù)庫(kù)ID自增  
    NONE(1),//該類型為未設(shè)置主鍵類型      
    INPUT(2),//手動(dòng)輸入ID
      		 //該類型可以通過(guò)自己注冊(cè)自動(dòng)填充插件進(jìn)行填充  
//以下3種類型、只有當(dāng)插入對(duì)象ID 為空，才自動(dòng)填充。     
    ID_WORKER(3),//全局唯一ID (idWorker)      
    UUID(4),//全局唯一ID (UUID)          
    ID_WORKER_STR(5);//字符串全局唯一ID (idWorker 的字符串表示) 
}

//主鍵自增配合 數(shù)據(jù)庫(kù)主鍵自增使用
@TableId(type = IdType.AUTO)

@Test
    void updateUser(){
        User user = new User();
        user.setId(new Long(201916129));
//        user.setName("張三");
        user.setAge(18);
        usermapper.updateById(user);
    }

    private Date createTime;    //開(kāi)始時(shí)間
    private Date updateTime;  //更新時(shí)間

@TableField(fill = FieldFill.INSERT)
private Date createTime;    //開(kāi)始時(shí)間
@TableField(fill = FieldFill.INSERT_UPDATE)
private Date updateTime;  //更新時(shí)間

package com.sxau.handle;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.util.Date;

@Slf4j
@Component //把處理器加到IOC容器中
public class myMetaObjectHandle implements MetaObjectHandler {
    //插入時(shí)的填充策略
    @Override
    public void insertFill(MetaObject metaObject) {
        log.info("Start insert fill.... ");
        this.setFieldValByName("createTime",new Date(),metaObject);
        this.setFieldValByName("updateTime",new Date(),metaObject);
    }
    //更新時(shí)的填充策略
    @Override
    public void updateFill(MetaObject metaObject) {
        log.info("Start update fill.... ");
        this.setFieldValByName("updateTime",new Date(),metaObject);
    }
}

@ComponentScan("com.sxau.handle")

    @Test
    void insertUser(){
        User user = new User();
//      user.setId(new Long(201916127));
        user.setName("渣渣輝");
        user.setAge(10);
        user.setEmail("1016942589@qq.com");
        usermapper.insert(user);
        System.out.println(user.toString());
    }
    @Test
    void updateUser(){
        User user = new User();
        user.setId(new Long(201916137));
        user.setName("李麗");
        user.setAge(20);
        usermapper.updateById(user);
    }

//測(cè)試批量查詢
@Test
public void selectByBatchId(){
    List<User> users = usermapper.selectBatchIds(Arrays.asList(1, 2, 3));
    users.forEach(System.out::println);
}
//多條件查詢用map
@Test
public void selectByBatchIds(){
    HashMap<String, Object> map = new HashMap<>();
    map.put("age",20);
    List<User> users = usermapper.selectByMap(map);
    for (User user : users) {
        System.out.println(user);
    }
}