MyBatis-Plus快速上手

其他 2021-03-18 17:48:29 阅读次数: 0

官方文档

https://mp.baomidou.com/

创建SpringBoot项目，添加以下依赖

		<dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.0.5</version>
        </dependency>

这里用的版本是3.0.5，需要新版可以参照官方文档快速入门

数据库

在这里插入图片描述

Sql代码

use mybatisPlus;
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)
);
insert into user(id,name,age,email) values
(1,'Jone',18,'test1qq.com'),
(2,'Jack',20,'test2qq.com'),
(3,'Tom',28,'test3qq.com'),
(4,'Sandy',21,'test4qq.com'),
(5,'Billie',24,'test5qq.com');

-- 设置主键自增
ALTER TABLE `mybatisplus`.`user` 
CHANGE COLUMN `id` `id` BIGINT(20) NOT NULL AUTO_INCREMENT COMMENT '主键ID' ;

-- 增加创建和更新时间字段
ALTER TABLE `mybatisplus`.`user` 
ADD COLUMN `create_time` DATETIME NULL COMMENT '创建时间' AFTER `email`,
ADD COLUMN `update_time` DATETIME NULL COMMENT '更新时间' AFTER `create_time`;

-- 增加乐观锁
ALTER TABLE `mybatisplus`.`user` 
ADD COLUMN `version` INT(10) NULL DEFAULT 1 COMMENT '乐观锁' AFTER `email`;

-- 增加逻辑删除字段
ALTER TABLE `mybatisplus`.`user` 
ADD COLUMN `deleted` INT(1) NULL DEFAULT 0 COMMENT '逻辑删除' AFTER `version`;

POJO(Entity)实体类

package com.zzf.mybatis_plus.pojo;

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

import java.util.Date;

/*
 *
 *@author:zzf
 *@time:2021-01-19
 *
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    
    
    @TableId(type=IdType.AUTO)//可设置不同的主键策略，默认是雪花算法
    private Integer id;
    private String name;
    private Integer age;
    private String email;

    @Version//乐观锁（每次更新先查询version值，在此基础上比较和加1，如果多线程可能会出现更新失败）
    private Integer version;

    @TableLogic//逻辑删除
    private Integer deleted;

    @TableField(fill = FieldFill.INSERT)//自动填充
    private Date createTime;
    @TableField(fill = FieldFill.INSERT_UPDATE)//自动填充
    private Date updateTime;
}

要实现自动填充，需要添加handler

package com.zzf.mybatis_plus.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;

/*
 *
 *@author:zzf
 *@time:2021-01-20
 *
 */
@Slf4j
@Component//放进IOC容器
public class MyMetaObjectHandler implements MetaObjectHandler {
    
    
    @Override
    public void insertFill(MetaObject metaObject) {
    
    
        log.info("start insert fill....");//插入时填充
        this.setFieldValByName("createTime",new Date(),metaObject);
        this.setFieldValByName("updateTime",new Date(),metaObject);

    }

    @Override
    public void updateFill(MetaObject metaObject) {
    
    
        log.info("start update fill....");//更新时填充
        this.setFieldValByName("updateTime",new Date(),metaObject);

    }
}

添加相关插件的所需的配置类

package com.zzf.mybatis_plus.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.apache.ibatis.annotations.Property;
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;

/*
 *
 *@author:zzf
 *@time:2021-01-20
 *
 */
@MapperScan("com.zzf.mybatis_plus.mapper")
@EnableTransactionManagement
@Configuration//配置类
public class MyBatisPlusConnfig {
    
    
    //乐观锁插件
    @Bean
    public OptimisticLockerInterceptor optimisticLockerInterceptor(){
    
    
        return new OptimisticLockerInterceptor();
    }

    //分页插件
    @Bean
    public PaginationInterceptor paginationInterceptor(){
    
    
        return new PaginationInterceptor();
    }

    //逻辑删除组件
    //逻辑删除是为了方便数据恢复和保护数据本身价值等等的一种方案
    @Bean
    public ISqlInjector sqlInjector(){
    
    
        return new LogicSqlInjector();
    }

    @Bean
    @Profile({
    
    "dev","test"})
    public PerformanceInterceptor performanceInterceptor(){
    
    
        PerformanceInterceptor performanceInterceptor=new PerformanceInterceptor();
        performanceInterceptor.setMaxTime(1000);//设置sql执行的最大时间，如果超过了则不执行
        performanceInterceptor.setFormat(true);
        return performanceInterceptor;
    }

}

配置文件application.properties

##配置开发环境
spring.profiles.active=dev

# 应用名称
spring.application.name=mybatis_plus
# 应用服务 WEB 访问端口
server.port=8080

spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.url=jdbc:mysql://localhost:3306/mybatisPlus?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
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

#配置逻辑删除
mybatis-plus.global-config.db-config.logic-delete-value=1
mybatis-plus.global-config.db-config.logic-not-delete-value=0

持久层

package com.zzf.mybatis_plus.mapper;

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

/*
 *
 *@author:zzf
 *@time:2021-01-19
 *
 */
@Repository//代表持久层
public interface UserMapper extends BaseMapper<User> {
    
    
}

简单CRUD测试

package com.zzf.mybatis_plus;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.zzf.mybatis_plus.mapper.UserMapper;
import com.zzf.mybatis_plus.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;

@SpringBootTest
class MybatisPlusApplicationTests {
    
    

    @Autowired
    private UserMapper userMapper;

    @Test
    void contextLoads() {
    
    

        //查询全部用户，参数为Wrapper条件构建器，先设为null
        List<User> users = userMapper.selectList(null);
        users.forEach(System.out::println);

    }

    //测试插入
    @Test
    void testInsert(){
    
    
        User user=new User();
        user.setName("aaaaaBO");
        user.setAge(18);
        user.setEmail("[email protected]");
        userMapper.insert(user);
    }

    //测试更新
    @Test
    void testUpdate(){
    
    
        User user=new User();
        //通过条件自动拼装动态sql
        user.setId(8);
        user.setName("HHHa");
        user.setAge(22);
        int i=userMapper.updateById(user);
        System.out.println(i);
    }

    //测试乐观锁(单线程）
    @Test
    public void testOptimisticLocker(){
    
    
        //查询用户信息
        User user=userMapper.selectById(8L);
        //修改
        user.setName("Kkkkg");
        user.setEmail("[email protected]");
        userMapper.updateById(user);
    }

    //测试乐观锁(多线程）
    @Test
    void testOptimisticLocker2(){
    
    
        //线程1
        User user=userMapper.selectById(8L);
        user.setName("zzf");
        user.setEmail("[email protected]");

        //模拟另外一线程执行了插队操作
        User user2=userMapper.selectById(8L);
        user2.setName("zzzf");
        user2.setEmail("[email protected]");
        userMapper.updateById(user2);
        userMapper.updateById(user);
    }

    //测试查询ById
    @Test
    void testSelectById(){
    
    
        User user =userMapper.selectById(8L);
        System.out.println(user);
    }

    //测试批量查询
    @Test
    void testSelectByBatchId(){
    
    
        List<User> users=userMapper.selectBatchIds(Arrays.asList(6,7,8));
        users.forEach(System.out::println);
    }

    //测试按条件查询By map
    @Test
    void testSelectByMap(){
    
    
        HashMap<String, Object> map = new HashMap();
        map.put("name","zzzf");
        map.put("age",22);
        List<User> users = userMapper.selectByMap(map);
        users.forEach(System.out::println);
    }
    //测试分页查询
    @Test
    void testPage(){
    
    
        //参数1：当前页，页面大小
        //参数2：页面大小
        Page<User> page = new Page<>(2, 5);
        userMapper.selectPage(page,null);
    }

    //测试删除
    @Test
    void testDeleteById(){
    
    
        userMapper.deleteById(1);
    }

    //通过id批量删除
    @Test
    void testDeleteBatchById(){
    
    
        userMapper.deleteBatchIds(Arrays.asList(2,3));
    }

    //通过Map删除
    @Test
    void testDeleteByMap(){
    
    
        HashMap<String, Object> map=new HashMap<>();
        map.put("name","JoLin");
        userMapper.deleteByMap(map);
    }

    //测试逻辑删除
    @Test
    void tsetLogicDelete(){
    
    
        userMapper.deleteById(5);
    }
}

基于条件构造器的测试

package com.zzf.mybatis_plus;

import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.zzf.mybatis_plus.mapper.UserMapper;
import com.zzf.mybatis_plus.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;

/*
 *
 *@author:zzf
 *@time:2021-01-20
 *
 */
@SpringBootTest
public class WrapperTest {
    
    

    @Autowired
    private UserMapper userMapper;
    @Test
    void contextLoads(){
    
    
        //查询name不为空的用户，并且邮箱不为空，年龄大于等于12
        QueryWrapper<User> wrapper=new QueryWrapper<>();
        wrapper.isNotNull("name")
                .isNotNull("email")
                .ge("age",21);
        userMapper.selectList(wrapper).forEach(System.out::println);
    }

    //查询一个结果
    @Test
    void test2(){
    
    
        QueryWrapper<User> wrapper=new QueryWrapper<>();
        wrapper.eq("name","JOBO");
        User user=userMapper.selectOne(wrapper);
        System.out.println(user);
    }

    //查询结果数量
    @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);//区间
        Integer count = userMapper.selectCount(wrapper);
        System.out.println(count);
    }

    //模糊查询
    @Test
    void test4(){
    
    
        QueryWrapper<User> wrapper=new QueryWrapper<>();
        wrapper.notLike("name","e")//不包含e
                .likeRight("email","t");//以t开头，即t%
        List<User> users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }
    //子查询
    @Test
    void test5(){
    
    
        QueryWrapper<User> wrapper=new QueryWrapper<>();
        wrapper.inSql("id","select id from user where id>3");
        List<User> users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }

    //排序查询
    @Test
    void test6(){
    
    
        QueryWrapper<User> wrapper=new QueryWrapper<>();
        wrapper.orderByDesc("id");
        List<User> users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }
}

代码生成器

先添加相关依赖

 		<!-- https://mvnrepository.com/artifact/com.spring4all/swagger-spring-boot-starter -->
        <dependency>
            <groupId>com.spring4all</groupId>
            <artifactId>swagger-spring-boot-starter</artifactId>
            <version>1.9.0.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.baomidou/mybatis-plus-generator -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.0.5</version>
        </dependency>

        <dependency>
            <groupId>org.apache.velocity</groupId>
            <artifactId>velocity-engine-core</artifactId>
            <version>2.2</version>
        </dependency>

package util;

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;

/*
 *
 *@author:zzf
 *@time:2021-01-20
 *
 */
public class GenerateCode {
    
    
    public static void main(String[] args) {
    
    
        //构建代码自动生成器对象
        AutoGenerator mpg=new AutoGenerator();
        //配置策略

        //全局配置
        GlobalConfig gc=new GlobalConfig();
        String projectPath=System.getProperty("user.dir");
        gc.setOutputDir(projectPath+"/src/main/java");
        gc.setAuthor("zzf");
        gc.setOpen(false);
        gc.setFileOverride(false);//是否覆盖
        gc.setServiceName("%sService");//去掉I前缀
        gc.setIdType(IdType.AUTO);
        gc.setDateType(DateType.ONLY_DATE);
        gc.setSwagger2(true);
        mpg.setGlobalConfig(gc);

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

        //包配置
        PackageConfig packageConfig = new PackageConfig();
        packageConfig.setModuleName("plus_test");
        packageConfig.setParent("com.zzf.mybatis_plus");
        packageConfig.setEntity("entity");
        packageConfig.setMapper("mapper");
        packageConfig.setService("service");
        packageConfig.setController("controller");
        mpg.setPackageInfo(packageConfig);
        //策略配置
        StrategyConfig strategyConfig=new StrategyConfig();
        strategyConfig.setInclude("user");//要映射的表，可传多个参数表示多张表
        strategyConfig.setNaming(NamingStrategy.underline_to_camel);
        strategyConfig.setColumnNaming(NamingStrategy.underline_to_camel);
        strategyConfig.setEntityLombokModel(true);//自动lombok

        strategyConfig.setLogicDeleteFieldName("deleted");//逻辑删除
        //自动填充配置
        TableFill createTime=new TableFill("create_time", FieldFill.INSERT);
        TableFill updateTime=new TableFill("update_time", FieldFill.INSERT_UPDATE);
        ArrayList<TableFill> tableFills=new ArrayList<>();
        tableFills.add(updateTime);
        tableFills.add(createTime);
        strategyConfig.setTableFillList(tableFills);

        //乐观锁
        strategyConfig.setVersionFieldName("version");

        //controller风格
        strategyConfig.setRestControllerStyle(true);

        mpg.setStrategy(strategyConfig);

        mpg.execute();


    }
}

使用后能自动生成entity、mapper、service、controller层的代码

参考：
https://www.bilibili.com/video/BV17E411N7KN

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