1. MyBatisPlus

MyBatisPlus Learning Video: Mad God Says MyBatisPlus Tutorial

KuangStudy
https://www.kuangstudy.com/course

MyBatisPlus学习视频:
https://www.bilibili.com/video/BV17E411N7KN?p=1

MyBatisPlus官网：https://baomidou.com/

MyBatisPlus文档：https://baomidou.com/pages/24112f/

1. Introduction to MyBatisPlus

MyBatisPlus official website: https://baomidou.com/

MyBatisPlus document: https://baomidou.com/pages/24112f/

1642410819954

Two, characteristics

No intrusion : only enhancement and no change, the introduction of it will not affect the existing project, as smooth as silk
Low loss : the basic CURD will be automatically injected when it is started, the performance is basically lossless, and the object-oriented operation is directly performed
Powerful CRUD operations : Built-in general Mapper and general Service, most of the CRUD operations on a single table can be realized with only a small amount of configuration, and there is a powerful condition constructor to meet various usage needs
Support Lambda form call : through Lambda expressions, it is convenient to write various query conditions, no need to worry about field typos
Supports automatic primary key generation : supports up to 4 primary key strategies (including a distributed unique ID generator - Sequence), which can be freely configured to perfectly solve the primary key problem
Support ActiveRecord mode : support ActiveRecord form call, the entity class only needs to inherit the Model class to perform powerful CRUD operations
Support custom global general operations : support global general method injection ( Write once, use anywhere )
Built-in code generator : use code or Maven plug-in to quickly generate Mapper, Model, Service, Controller layer code, support template engine, and more custom configurations are waiting for you to use
Built-in paging plug-in : Based on MyBatis physical paging, developers don't need to care about specific operations. After configuring the plug-in, writing paging is equivalent to ordinary List query
The paging plug-in supports multiple databases : supports MySQL, MariaDB, Oracle, DB2, H2, HSQL, SQLite, Postgre, SQLServer and other databases
Built-in performance analysis plug-in : It can output SQL statements and their execution time. It is recommended to enable this function during development and testing, which can quickly find out slow queries
Built-in global interception plug-in : Provides intelligent analysis and blocking of delete and update operations on the entire table, and can also customize interception rules to prevent misoperations

2. Quick start

Using third-party plugins:

Import the corresponding dependencies
Study how dependencies are configured
how the code is written
Improve and expand technical capabilities

1. Create a database`mybatis_plus`

DROP TABLE IF EXISTS user;

CREATE TABLE user
(
	id BIGINT(20) NOT NULL COMMENT '主键ID',
	name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
	age INT(11) NULL DEFAULT NULL COMMENT '年龄',
	email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
	PRIMARY KEY (id)
);
--真实开发环境中,version(乐观锁),deleted(逻辑删除),gmt_create,gmt_modified
DELETE FROM user;

INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, '[email protected]'),
(2, 'Jack', 20, '[email protected]'),
(3, 'Tom', 28, '[email protected]'),
(4, 'Sandy', 21, '[email protected]'),
(5, 'Billie', 24, '[email protected]');

1642413075576

2. Write the project and use SpringBoot to initialize!

1642411303117

1642411321622

3. Import dependencies

注:我们使用mybatis-plus 可以节省我们大量的代码,尽量不要同时导入mybatis和mybatis-plus因为版本有差异!

<?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>2.6.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.Jin</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>
        <!--数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.22</version>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.16</version>
        </dependency>
        <!--mybatis_plus是自己开发的，并非官方的-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.0.5</version>
        </dependency>
        <!-- 代码生成器模板引擎 -->
        <dependency>
            <groupId>org.apache.velocity</groupId>
            <artifactId>velocity-engine-core</artifactId>
            <version>2.0</version>
        </dependency>
        <dependency>
            <groupId>hu.blackbelt.bundles.swagger-parser</groupId>
            <artifactId>io.swagger.parser</artifactId>
            <version>1.0.47_1</version>
        </dependency>

        <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>
    </dependencies>

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

</project>

4. application.properties configuration file

#设置开发环境
spring.profiles.active=dev
#mysql 8
spring.datasource.username=root
spring.datasource.password=123456
#spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus?useUnicode=true&characterEncoding=UTF-8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
#serverTimezone=Asia/Shanghai        serverTimezone=GMT%2B8
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#配置日志
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
#逻辑删除配置
mybatis-plus.global-config.db-config.logic-delete-value=1
mybatis-plus.global-config.db-config.logic-not-delete-value=0

5. Write pojo

package com.jin.pojo;

import com.baomidou.mybatisplus.annotation.*;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.Date;

/**
 * @Package:com.jin.pojo
 * @ClassName: User
 * @Description:
 * @Date: 2021/12/06 17:12
 * @Author: Jin
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
@TableName("user")
public class User {
    
    
    /**
     * Auto	            数据库自增
     * Input	        自行输入
     * ID_Worker	    分布式全局唯一ID 长整型类型
     * UUID	3           2位UUID字符串、全局唯一id uuid
     * NONE	            无状态
     * ID_WORKER_STR	分布式全局唯一ID 字符串类型
     */
    @TableId(type = IdType.AUTO)
    private Long id;
    private String name;
    private Integer age;
    private String email;

    @Version//乐观锁Version注解
    private Integer version;

    @TableLogic//逻辑删除注解
    private Integer deleted;

    //字段添加填充内容
    @TableField(fill = FieldFill.INSERT)
    private Date createTime;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date updateTime;
}

6. Write mapper

package com.jin.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.jin.pojo.User;
import org.springframework.stereotype.Repository;

/**
 * @Package:com.jin.mapper
 * @ClassName: Usermapper
 * @Description:
 * @Date: 2021/12/06 17:14
 * @Author: Jin
 */
@Repository//代表持久层
//在mybatis_plus上面继承基本的类BaseMapper
public interface UserMapper extends BaseMapper<User> {
    
    

}

7. Startup class configuration

package com.jin;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

//扫描mapper文件夹
@MapperScan("com.Jin.mapper")
@SpringBootApplication
public class MybatisPlusApplication {
    
    

    public static void main(String[] args) {
    
    
        SpringApplication.run(MybatisPlusApplication.class, args);
    }

}

8. Test

package com.jin;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.jin.mapper.UserMapper;
import com.jin.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@SpringBootTest
class MybatisPlusApplicationTests {
    
    

    @Autowired
    private UserMapper userMapper;

    @Test
    void contextLoads() {
    
    
        List<User> users = userMapper.selectList(null);
        for (User user : users) {
    
    
            System.out.println(user);
        }
        System.out.println();
        users.forEach(System.out::println);
    }
}

9. Output result

1642411896677

3. Configuration log

Configuration log in properties

#配置日志
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

4. MyMetaObjectHandler

package com.jin.handler;

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;

/**
 * @Package:com.jin.handler
 * @ClassName: MyMetaObjectHandler
 * @Description:	处理器，自动填充插入和更新时间
 * @Date: 2021/12/07 9:20
 * @Author: Jin
 */
@Slf4j
@Component //把处理器加到IOC容器中
public class MyMetaObjectHandler implements MetaObjectHandler {
    
    
    //插入时的填充策略
    @Override
    public void insertFill(MetaObject metaObject) {
    
    
        log.info("start insert fill...");
        //    default MetaObjectHandler setFieldValByName(String fieldName, Object fieldVal, MetaObject metaObject) {
    
    
        this.setFieldValByName("createTime",new Date(),metaObject);
        this.setFieldValByName("updateTime",new Date(),metaObject);
    }
    //更新时的填充策略
    @Override
    public void updateFill(MetaObject metaObject) {
    
    
        log.info("start update fill...");
        this.setFieldValByName("updateTime",new Date(),metaObject);
    }
}

Five, MyBatisPlusConfig

package com.jin.config;

import com.baomidou.mybatisplus.core.injector.ISqlInjector;
import com.baomidou.mybatisplus.extension.injector.LogicSqlInjector;
import com.baomidou.mybatisplus.extension.plugins.OptimisticLockerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PerformanceInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import org.springframework.transaction.annotation.EnableTransactionManagement;

/**
 * @Package:com.jin.config
 * @ClassName: MyBatisPlusConfig
 * @Description:
 * @Date: 2021/12/07 9:51
 * @Author: Jin
 */
//扫描我们的mapper文件夹
@MapperScan("com.Jin.mapper")
@EnableTransactionManagement
@Configuration               //配置类
public class MyBatisPlusConfig {
    
    
    /**
     * 旧版
     * //注册乐观锁插件
     */
    @Bean
    public OptimisticLockerInterceptor optimisticLockerInterceptor() {
    
    
        return new OptimisticLockerInterceptor();
    }
    /**
     * 旧版
     * 分页插件
     */
    @Bean
    public PaginationInterceptor paginationInterceptor() {
    
    
        return new PaginationInterceptor();
    }
    /**
     * 旧版
     * 逻辑删除组件
     */
    @Bean
    public ISqlInjector sqlInjector(){
    
    
        return new LogicSqlInjector();
    }
    /**
     * 性能分析插件
     */
    @Bean
    @Profile({
    
    "dev","test"}) //设置dev 和 test环境开启,保障开发效率
    public PerformanceInterceptor performanceInterceptor(){
    
    
        PerformanceInterceptor performanceInterceptor = new PerformanceInterceptor();
        //设置sql执行的最大时间，如果超过就不执行（报错，提示sql执行时间too large），不允许用户等待
        performanceInterceptor.setMaxTime(200);
        //是否格式化代码
        performanceInterceptor.setFormat(true);
        return performanceInterceptor;
    }
}

六、MybatisPlusApplicationTests

package com.jin;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.jin.mapper.UserMapper;
import com.jin.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@SpringBootTest
class MybatisPlusApplicationTests {
    
    

    @Autowired
    private UserMapper userMapper;
	//查询所有数据
    @Test
    void contextLoads() {
    
    
        List<User> users = userMapper.selectList(null);
        for (User user : users) {
    
    
            System.out.println(user);
        }
        System.out.println();
        users.forEach(System.out::println);
    }
    //测试插入
    @Test
    public void insert(){
    
    
        User user = new User();
        user.setName("Yangon");
        user.setAge(11);
        user.setEmail("[email protected]");
        int insert = userMapper.insert(user);
        System.out.println(insert);
        System.out.println(user);
    }
    //测试更新
    @Test
    public void update(){
    
    
        User user = new User();
        user.setId(1L);
        user.setName("JiWu");
        user.setAge(99);
        int i = userMapper.updateById(user);
        System.out.println(i);
        System.out.println(user);
    }
    //测试乐观锁成功！
    @Test
    public void testOptimisticLocker(){
    
    
        //1、查询用户信息
        User user = userMapper.selectById(1L);
        System.out.println(user);
        //2、修改用户信息
        user.setName("Nameddd");
        user.setEmail("[email protected]");
        //3、执行更新操作
        userMapper.updateById(user);
    }
    //测试乐观锁失败！多线程下
    @Test
    public void testOptimisticLocker2(){
    
    
        //线程1
        User user = userMapper.selectById(1L);
        System.out.println(user);
        user.setName("Nameddd");
        user.setEmail("[email protected]");
        //模拟另外一个线程执行了插队操作
        User user2 = userMapper.selectById(1L);
        System.out.println(user);
        user2.setName("Nameddd2222");
        user2.setEmail("[email protected]");
        userMapper.updateById(user2);
        //自旋锁来多次尝试提交！
        userMapper.updateById(user);//如果没有乐观锁就会覆盖插队线程的值！
    }

    //测试按id查询
    @Test
    public void testSelectById(){
    
    
        User user = userMapper.selectById(1L);
        System.out.println(user);
    }
    //测试按批量查询
    @Test
    public void testSelectBatchId(){
    
    
        List<User> users = userMapper.selectBatchIds(Arrays.asList(1, 2, 3));
        System.out.println(users);
        System.out.println();
        users.forEach(System.out::println);
    }

    //测试按条件map查询
    @Test
    public void testSelectByMap(){
    
    
        HashMap<String, Object> map = new HashMap<>();
        //自定义查询
        map.put("name","JiWu");
        map.put("email","[email protected]");
        List<User> users = userMapper.selectByMap(map);
        users.forEach(System.out::println);
    }

    //测试分页查询
    @Test
    public void testPage(){
    
    
        //参数一：当前页
        //参数二：页面大小
        Page<User> page = new Page<>(2,5);
        userMapper.selectPage(page,null);
        page.getRecords().forEach(System.out::println);
        System.out.println(page.getTotal());
    }

    //测试根据id删除记录
    @Test
    public void testDeleteById(){
    
    
        int i = userMapper.deleteById(1L);
        System.out.println(i);
    }
    //测试根据id批量删除记录
    @Test
    public void testDeleteBatchIds(){
    
    
        int i = userMapper.deleteBatchIds(Arrays.asList(1467789606408249346L, 1467789606408249347L, 1467789606408249348L, 1467789606408249349L));
        System.out.println(i);
    }
    //测试通过Map删除记录
    @Test
    public void testDeleteByMap(){
    
    
        HashMap<String, Object> map = new HashMap<>();
        map.put("id",1467789606408249351L);
        int i = userMapper.deleteByMap(map);
        System.out.println(i);
    }
}

7. Wrapper Test

package com.jin;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.jin.mapper.UserMapper;
import com.jin.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;
import java.util.Map;

/**
 * @Package:com.jin
 * @ClassName: WrapperTest
 * @Description:
 * @Date: 2021/12/07 15:16
 * @Author: Jin
 */
@SpringBootTest
public class WrapperTest {
    
    
    @Autowired
    private UserMapper userMapper;

    @Test
    void contextLoads() {
    
    
        //查询name！=null和并且邮箱不为空的用户，年龄大于等于12
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper
            .isNotNull("name")
            .isNotNull("email")
            .ge("age",12);
        userMapper.selectList(wrapper).forEach(System.out::println);
    }
    @Test
    void test2(){
    
    
        //查询名字JiWu
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        //查询一个数据，出现多个结果使用List或者Map
        wrapper.eq("name","Tom");
        User user = userMapper.selectOne(wrapper);
        System.out.println(user);
    }
    @Test
    void test3(){
    
    
        //查询年龄在20~30岁之间的用户
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.between("age",20,30);
        Integer count = userMapper.selectCount(wrapper);
        System.out.println(count);
    }
    @Test
    void test4(){
    
    
        //查询名字里面不包含Ji
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.notLike("name","Ji")
            .likeRight("email","t");
        List<Map<String, Object>> maps = userMapper.selectMaps(wrapper);
        maps.forEach(System.out::println);
    }
    @Test
    void test5(){
    
    
        //查询联表
        //id在子查询中查出来
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.inSql("id","select id from user where id<3");
        List<Object> objects = userMapper.selectObjs(wrapper);
        objects.forEach(System.out::println);
    }
    @Test
    void test6(){
    
    
        //查询通过id进行排序
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.orderByDesc("id");
        List<User> users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }
}

1644330566760

8. Code generator

package com.jin;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.annotation.FieldFill;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.generator.AutoGenerator;
import com.baomidou.mybatisplus.generator.config.DataSourceConfig;
import com.baomidou.mybatisplus.generator.config.GlobalConfig;
import com.baomidou.mybatisplus.generator.config.PackageConfig;
import com.baomidou.mybatisplus.generator.config.StrategyConfig;
import com.baomidou.mybatisplus.generator.config.po.TableFill;
import com.baomidou.mybatisplus.generator.config.rules.DateType;
import com.baomidou.mybatisplus.generator.config.rules.NamingStrategy;

import java.util.ArrayList;

/**
 * @Package:com.jin
 * @ClassName: JinCode
 * @Description:代码自动生成器
 * @Date: 2021/12/07 16:17
 * @Author: Jin
 */
// 代码自动生成器
public class JinCode {
    
    
    public static void main(String[] args) {
    
    
        // 需要构建一个 代码自动生成器 对象
        AutoGenerator mpg = new AutoGenerator();

        // 配置策略
        // 1、全局配置
        GlobalConfig gc = new GlobalConfig();
        String projectPath = System.getProperty("user.dir");
        gc.setOutputDir(projectPath+"/src/main/java");
        gc.setAuthor("Jin"); gc.setOpen(false);
        gc.setFileOverride(false);

        // 是否覆盖
        gc.setServiceName("%sService");

        // 去Service的I前缀
        gc.setIdType(IdType.ID_WORKER);
        gc.setDateType(DateType.ONLY_DATE);
        gc.setSwagger2(true);
        mpg.setGlobalConfig(gc);

        //2、设置数据源
        DataSourceConfig dsc = new DataSourceConfig();
        dsc.setUrl("jdbc:mysql://localhost:3306/test? useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8");
        dsc.setDriverName("com.mysql.cj.jdbc.Driver");
        dsc.setUsername("root");
        dsc.setPassword("123456");
        dsc.setDbType(DbType.MYSQL); mpg.setDataSource(dsc);

        //3、包的配置
        PackageConfig pc = new PackageConfig();
        //只需要改实体类名字 和包名 还有 数据库配置即可
        pc.setModuleName("blog"); pc.setParent("com.Jin");
        pc.setEntity("entity"); pc.setMapper("mapper");
        pc.setService("service"); pc.setController("controller");
        mpg.setPackageInfo(pc);

        //4、策略配置
        StrategyConfig strategy = new StrategyConfig();
        strategy.setInclude("account","emp","dept");

        // 设置要映射的表名
        strategy.setNaming(NamingStrategy.underline_to_camel);
        strategy.setColumnNaming(NamingStrategy.underline_to_camel);
        strategy.setEntityLombokModel(true);

        // 自动lombok；
        strategy.setLogicDeleteFieldName("deleted");

        // 自动填充配置
        TableFill gmtCreate = new TableFill("gmt_create", FieldFill.INSERT);
        TableFill gmtModified = new TableFill("gmt_modified", FieldFill.INSERT_UPDATE);
        ArrayList<TableFill> tableFills = new ArrayList<>();
        tableFills.add(gmtCreate); tableFills.add(gmtModified);
        strategy.setTableFillList(tableFills);

        // 乐观锁
        strategy.setVersionFieldName("version");
        strategy.setRestControllerStyle(true);
        strategy.setControllerMappingHyphenStyle(true);

        // localhost:8080/hello_id_2
        mpg.setStrategy(strategy);
        mpg.execute(); //执行
    }
}

output result

1642412681888

MyBatisPlus Tutorial

1. MyBatisPlus

1. Introduction to MyBatisPlus

1. Introduction to MyBatisPlus

Two, characteristics

2. Quick start

1. Create a databasemybatis_plus

2. Write the project and use SpringBoot to initialize!

3. Import dependencies

4. application.properties configuration file

5. Write pojo

6. Write mapper

7. Startup class configuration

8. Test

9. Output result

3. Configuration log

4. MyMetaObjectHandler

Five, MyBatisPlusConfig

六、MybatisPlusApplicationTests

7. Wrapper Test

8. Code generator

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