给你 2 万条数据，怎么快速导入到 MySQL？写得太好了！

Posted Hollis Chuang

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Hollis的新书限时折扣中，一本深入讲解Java基础的干货笔记！

来源：blog.csdn.net/kisscatforever/

article/details/79817039

一、前言

前两天做了一个导入的功能，导入开始的时候非常慢，导入2w条数据要1分多钟，后来一点一点的优化，从直接把list怼进mysql中，到分配把list导入Mysql中，到多线程把list导入Mysql中。时间是一点一点的变少了。非常的爽，最后变成了10s以内。下面就展示一下过程。

基于 Spring Boot + MyBatis Plus + Vue & Element 实现的后台管理系统 + 用户小程序，支持 RBAC 动态权限、多租户、数据权限、工作流、三方登录、支付、短信、商城等功能。

项目地址：https://github.com/YunaiV/ruoyi-vue-pro

二、直接把list怼进Mysql

使用mybatis的批量导入操作：

@Transactional(rollbackFor = Exception.class)
    public int addFreshStudentsNew2(List<FreshStudentAndStudentModel> list, String schoolNo) 
        if (list == null || list.isEmpty()) 
            return 0;
        
        List<StudentEntity> studentEntityList = new LinkedList<>();
        List<EnrollStudentEntity> enrollStudentEntityList = new LinkedList<>();
        List<AllusersEntity> allusersEntityList = new LinkedList<>();

        for (FreshStudentAndStudentModel freshStudentAndStudentModel : list) 

            EnrollStudentEntity enrollStudentEntity = new EnrollStudentEntity();
            StudentEntity studentEntity = new StudentEntity();
            BeanUtils.copyProperties(freshStudentAndStudentModel, studentEntity);
            BeanUtils.copyProperties(freshStudentAndStudentModel, enrollStudentEntity);
            String operator = TenancyContext.UserID.get();
            String studentId = BaseUuidUtils.base58Uuid();
            enrollStudentEntity.setId(BaseUuidUtils.base58Uuid());
            enrollStudentEntity.setStudentId(studentId);
            enrollStudentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard());
            enrollStudentEntity.setOperator(operator);
            studentEntity.setId(studentId);
            studentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard());
            studentEntity.setOperator(operator);
            studentEntityList.add(studentEntity);
            enrollStudentEntityList.add(enrollStudentEntity);

            AllusersEntity allusersEntity = new AllusersEntity();
            allusersEntity.setId(enrollStudentEntity.getId());
            allusersEntity.setUserCode(enrollStudentEntity.getNemtCode());
            allusersEntity.setUserName(enrollStudentEntity.getName());
            allusersEntity.setSchoolNo(schoolNo);
            allusersEntity.setTelNum(enrollStudentEntity.getTelNum());
            allusersEntity.setPassword(enrollStudentEntity.getNemtCode());  //密码设置为考生号
            allusersEntityList.add(allusersEntity);
        
            enResult = enrollStudentDao.insertAll(enrollStudentEntityList);
            stuResult = studentDao.insertAll(studentEntityList);
            allResult = allusersFacade.insertUserList(allusersEntityList);

        if (enResult > 0 && stuResult > 0 && allResult) 
            return 10;
        
        return -10;
    

Mapper.xml

<insert id="insertAll" parameterType="com.dmsdbj.itoo.basicInfo.entity.EnrollStudentEntity">
        insert into tb_enroll_student
        <trim prefix="(" suffix=")" suffixOverrides=",">
                id,  
                remark,  
                nEMT_aspiration,  
                nEMT_code,  
                nEMT_score,  
                student_id,  
                identity_card_id,  
                level,  
                major,  
                name,  
                nation,  
                secondary_college,  
                operator,  
                sex,  
                is_delete,  
                account_address,  
                native_place,  
                original_place,  
                used_name,  
                pictrue,  
                join_party_date,  
                political_status,  
                tel_num,  
                is_registry,  
                graduate_school,  
                create_time,  
                update_time        </trim>        
        values
        <foreach collection="list" item="item" index="index" separator=",">
        (
                #item.id,jdbcType=VARCHAR,
                #item.remark,jdbcType=VARCHAR,
                #item.nemtAspiration,jdbcType=VARCHAR,
                #item.nemtCode,jdbcType=VARCHAR,
                #item.nemtScore,jdbcType=VARCHAR,
                #item.studentId,jdbcType=VARCHAR,
                #item.identityCardId,jdbcType=VARCHAR,
                #item.level,jdbcType=VARCHAR,
                #item.major,jdbcType=VARCHAR,
                #item.name,jdbcType=VARCHAR,
                #item.nation,jdbcType=VARCHAR,
                #item.secondaryCollege,jdbcType=VARCHAR,
                #item.operator,jdbcType=VARCHAR,
                #item.sex,jdbcType=VARCHAR,
                0,
                #item.accountAddress,jdbcType=VARCHAR,
                #item.nativePlace,jdbcType=VARCHAR,
                #item.originalPlace,jdbcType=VARCHAR,
                #item.usedName,jdbcType=VARCHAR,
                #item.pictrue,jdbcType=VARCHAR,
                #item.joinPartyDate,jdbcType=VARCHAR,
                #item.politicalStatus,jdbcType=VARCHAR,
                #item.telNum,jdbcType=VARCHAR,
                #item.isRegistry,jdbcType=TINYINT,
                #item.graduateSchool,jdbcType=VARCHAR,
                now(),
                now()        
        )   
        </foreach>                
  </insert>

代码说明：

底层的mapper是通过逆向工程来生成的，批量插入如下，是拼接成类似：insert into tb_enroll_student（）values （），（）…….（）;

这样的缺点是，数据库一般有一个默认的设置，就是每次sql操作的数据不能超过4M。这样插入，数据多的时候，数据库会报错Packet for query is too large (6071393 > 4194304). You can change this value on the server by setting the max_allowed_packet' variable.，虽然我们可以通过

类似 修改 my.ini 加上 max_allowed_packet =67108864，67108864=64M，默认大小4194304 也就是4M

修改完成之后要重启mysql服务，如果通过命令行修改就不用重启mysql服务。

完成本次操作，但是我们不能保证项目单次最大的大小是多少，这样是有弊端的。所以可以考虑进行分组导入。

基于微服务的思想，构建在 B2C 电商场景下的项目实战。核心技术栈，是 Spring Boot + Dubbo 。未来，会重构成 Spring Cloud Alibaba 。

项目地址：https://github.com/YunaiV/onemall

三、分组把list导入Mysql中

同样适用mybatis批量插入，区别是对每次的导入进行分组计算，然后分多次进行导入：

@Transactional(rollbackFor = Exception.class)
    public int addFreshStudentsNew2(List<FreshStudentAndStudentModel> list, String schoolNo) 
        if (list == null || list.isEmpty()) 
            return 0;
        
        List<StudentEntity> studentEntityList = new LinkedList<>();
        List<EnrollStudentEntity> enrollStudentEntityList = new LinkedList<>();
        List<AllusersEntity> allusersEntityList = new LinkedList<>();

        for (FreshStudentAndStudentModel freshStudentAndStudentModel : list) 

            EnrollStudentEntity enrollStudentEntity = new EnrollStudentEntity();
            StudentEntity studentEntity = new StudentEntity();
            BeanUtils.copyProperties(freshStudentAndStudentModel, studentEntity);
            BeanUtils.copyProperties(freshStudentAndStudentModel, enrollStudentEntity);
            String operator = TenancyContext.UserID.get();
            String studentId = BaseUuidUtils.base58Uuid();
            enrollStudentEntity.setId(BaseUuidUtils.base58Uuid());
            enrollStudentEntity.setStudentId(studentId);
            enrollStudentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard());
            enrollStudentEntity.setOperator(operator);
            studentEntity.setId(studentId);
            studentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard());
            studentEntity.setOperator(operator);
            studentEntityList.add(studentEntity);
            enrollStudentEntityList.add(enrollStudentEntity);

            AllusersEntity allusersEntity = new AllusersEntity();
            allusersEntity.setId(enrollStudentEntity.getId());
            allusersEntity.setUserCode(enrollStudentEntity.getNemtCode());
            allusersEntity.setUserName(enrollStudentEntity.getName());
            allusersEntity.setSchoolNo(schoolNo);
            allusersEntity.setTelNum(enrollStudentEntity.getTelNum());
            allusersEntity.setPassword(enrollStudentEntity.getNemtCode());  //密码设置为考生号
            allusersEntityList.add(allusersEntity);
        

        int c = 100;
        int b = enrollStudentEntityList.size() / c;
        int d = enrollStudentEntityList.size() % c;

        int enResult = 0;
        int stuResult = 0;
        boolean allResult = false;

        for (int e = c; e <= c * b; e = e + c) 
            enResult = enrollStudentDao.insertAll(enrollStudentEntityList.subList(e - c, e));
            stuResult = studentDao.insertAll(studentEntityList.subList(e - c, e));
            allResult = allusersFacade.insertUserList(allusersEntityList.subList(e - c, e));
        
        if (d != 0) 
            enResult = enrollStudentDao.insertAll(enrollStudentEntityList.subList(c * b, enrollStudentEntityList.size()));
            stuResult = studentDao.insertAll(studentEntityList.subList(c * b, studentEntityList.size()));
            allResult = allusersFacade.insertUserList(allusersEntityList.subList(c * b, allusersEntityList.size()));
        

        if (enResult > 0 && stuResult > 0 && allResult) 
            return 10;
        
        return -10;
    

代码说明：

这样操作，可以避免上面的错误，但是分多次插入，无形中就增加了操作实践，很容易超时。所以这种方法还是不值得提倡的。

再次改进，使用多线程分批导入。

四、多线程分批导入Mysql

依然使用mybatis的批量导入，不同的是，根据线程数目进行分组，然后再建立多线程池，进行导入。

@Transactional(rollbackFor = Exception.class)
    public int addFreshStudentsNew(List<FreshStudentAndStudentModel> list, String schoolNo) 
        if (list == null || list.isEmpty()) 
            return 0;
        
        List<StudentEntity> studentEntityList = new LinkedList<>();
        List<EnrollStudentEntity> enrollStudentEntityList = new LinkedList<>();
        List<AllusersEntity> allusersEntityList = new LinkedList<>();

        list.forEach(freshStudentAndStudentModel -> 
            EnrollStudentEntity enrollStudentEntity = new EnrollStudentEntity();
            StudentEntity studentEntity = new StudentEntity();
            BeanUtils.copyProperties(freshStudentAndStudentModel, studentEntity);
            BeanUtils.copyProperties(freshStudentAndStudentModel, enrollStudentEntity);
            String operator = TenancyContext.UserID.get();
            String studentId = BaseUuidUtils.base58Uuid();
            enrollStudentEntity.setId(BaseUuidUtils.base58Uuid());
            enrollStudentEntity.setStudentId(studentId);
            enrollStudentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard());
            enrollStudentEntity.setOperator(operator);
            studentEntity.setId(studentId);
            studentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard());
            studentEntity.setOperator(operator);
            studentEntityList.add(studentEntity);
            enrollStudentEntityList.add(enrollStudentEntity);

            AllusersEntity allusersEntity = new AllusersEntity();
            allusersEntity.setId(enrollStudentEntity.getId());
            allusersEntity.setUserCode(enrollStudentEntity.getNemtCode());
            allusersEntity.setUserName(enrollStudentEntity.getName());
            allusersEntity.setSchoolNo(schoolNo);
            allusersEntity.setTelNum(enrollStudentEntity.getTelNum());
            allusersEntity.setPassword(enrollStudentEntity.getNemtCode());  //密码设置为考生号
            allusersEntityList.add(allusersEntity);
        );


        int nThreads = 50;

        int size = enrollStudentEntityList.size();
        ExecutorService executorService = Executors.newFixedThreadPool(nThreads);
        List<Future<Integer>> futures = new ArrayList<Future<Integer>>(nThreads);

        for (int i = 0; i < nThreads; i++) 
            final List<EnrollStudentEntity> EnrollStudentEntityImputList = enrollStudentEntityList.subList(size / nThreads * i, size / nThreads * (i + 1));
            final List<StudentEntity> studentEntityImportList = studentEntityList.subList(size / nThreads * i, size / nThreads * (i + 1));
            final List<AllusersEntity> allusersEntityImportList = allusersEntityList.subList(size / nThreads * i, size / nThreads * (i + 1));

           Callable<Integer> task1 = () -> 
          studentSave.saveStudent(EnrollStudentEntityImputList,studentEntityImportList,allusersEntityImportList);
               return 1;
            ;
          futures.add(executorService.submit(task1));
        
        executorService.shutdown();
        if (!futures.isEmpty() && futures != null) 
            return 10;
        
        return -10;
    

代码说明：

上面是通过应用ExecutorService 建立了固定的线程数，然后根据线程数目进行分组，批量依次导入。一方面可以缓解数据库的压力，另一个面线程数目多了，一定程度会提高程序运行的时间。缺点就是要看服务器的配置，如果配置好的话就可以开多点线程，配置差的话就开小点。

五、小结

通过使用这个操作真是不断的提高了，项目使用技巧也是不错。加油~~ 多线程哦~~

完

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