java多線程批量拆分List導(dǎo)入數(shù)據(jù)庫的實現(xiàn)過程

更新時間：2021年10月30日 14:56:34 作者：AresCarry

這篇文章主要給大家介紹了關(guān)于java多線程批量拆分List導(dǎo)入數(shù)據(jù)庫的相關(guān)資料,文中通過示例代碼介紹的非常詳細，對大家學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價值,需要的朋友可以參考下

一、前言

前兩天做了一個導(dǎo)入的功能，導(dǎo)入開始的時候非常慢，導(dǎo)入2w條數(shù)據(jù)要1分多鐘，后來一點一點的優(yōu)化，從直接把list懟進Mysql中，到分配把list導(dǎo)入Mysql中，到多線程把list導(dǎo)入Mysql中。時間是一點一點的變少了。非常的爽，最后變成了10s以內(nèi)。下面就展示一下過程。

二、直接把list懟進Mysql

使用mybatis的批量導(dǎo)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());  //密碼設(shè)置為考生號
            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>

代碼說明：

底層的mapper是通過逆向工程來生成的，批量插入如下，是拼接成類似： insert into tb_enroll_student（）values （），（）…….（）；

這樣的缺點是，數(shù)據(jù)庫一般有一個默認的設(shè)置，就是每次sql操作的數(shù)據(jù)不能超過4M。這樣插入，數(shù)據(jù)多的時候，數(shù)據(jù)庫會報錯Packet for query is too large (6071393 > 4194304). You can change this value on the server by setting the max_allowed_packet' variable.，雖然我們可以通過

類似修改 my.ini 加上 max_allowed_packet =67108864

67108864=64M

默認大小4194304 也就是4M

修改完成之后要重啟mysql服務(wù)，如果通過命令行修改就不用重啟mysql服務(wù)。

完成本次操作，但是我們不能保證項目單次最大的大小是多少，這樣是有弊端的。所以可以考慮進行分組導(dǎo)入。

三、分組把list導(dǎo)入Mysql中

同樣適用mybatis批量插入，區(qū)別是對每次的導(dǎo)入進行分組計算，然后分多次進行導(dǎo)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());  //密碼設(shè)置為考生號
            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;
    }

代碼說明：

這樣操作，可以避免上面的錯誤，但是分多次插入，無形中就增加了操作實踐，很容易超時。所以這種方法還是不值得提倡的。

再次改進，使用多線程分批導(dǎo)入。

四、多線程分批導(dǎo)入Mysql

依然使用mybatis的批量導(dǎo)入，不同的是，根據(jù)線程數(shù)目進行分組，然后再建立多線程池，進行導(dǎo)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());  //密碼設(shè)置為考生號
            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;
    }

代碼說明：

上面是通過應(yīng)用ExecutorService 建立了固定的線程數(shù)，然后根據(jù)線程數(shù)目進行分組，批量依次導(dǎo)入。一方面可以緩解數(shù)據(jù)庫的壓力，另一個面線程數(shù)目多了，一定程度會提高程序運行的時間。缺點就是要看服務(wù)器的配置，如果配置好的話就可以開多點線程，配置差的話就開小點。