给你 2 万条数据，怎么快速导入到 MySQL？写得太好了...

java研习社 06-28 860

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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。

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.

<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。

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。

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