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弱网分块续传实践

最近更新时间:2021-04-26 15:41:10

背景

本文主要介绍基于腾讯云对象存储(COS)服务,移动端在弱网情况下,如何根据实际情况动态调节上传分块大小,来提高上传成功率。

注意:

该功能目前处于灰度测试阶段,如需支持该功能,请 联系我们,申请开通白名单。

实践须知

  1. COS 目前支持最小分块大小为100KB。
  2. 分块越小,意味着请求数也多。目前根据测试统计,100KB分块大小的请求耗时是1MB分块大小的2倍左右。
  3. 在正常网络下发起请求,建议设置分块大小为1MB及以上。
  4. 在网络信号弱等网络环境下上传对象容易导致上传失败,可以考虑将分块大小设置为100KB,再重新上传。
  5. 分块大小设置越小,将来下载该文件时可能比较缓慢。

示例

Android SDK

下面举例在弱网络环境中,使用分块上传对象的示例代码:

import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import com.tencent.cos.xml.CosXmlService;
import com.tencent.cos.xml.CosXmlServiceConfig;
import com.tencent.cos.xml.common.ClientErrorCode;
import com.tencent.cos.xml.common.Region;
import com.tencent.cos.xml.exception.CosXmlClientException;
import com.tencent.cos.xml.exception.CosXmlServiceException;
import com.tencent.cos.xml.listener.CosXmlProgressListener;
import com.tencent.cos.xml.listener.CosXmlResultListener;
import com.tencent.cos.xml.model.CosXmlRequest;
import com.tencent.cos.xml.model.CosXmlResult;
import com.tencent.cos.xml.transfer.COSXMLUploadTask;
import com.tencent.cos.xml.transfer.TransferConfig;
import com.tencent.cos.xml.transfer.TransferManager;
import com.tencent.cos.xml.transfer.TransferState;
import com.tencent.cos.xml.transfer.TransferStateListener;
import com.tencent.qcloud.core.auth.QCloudCredentialProvider;
import com.tencent.qcloud.core.auth.ShortTimeCredentialProvider;
public class ResumeHelper {
  private final static String TAG = ResumeHelper.class.getSimpleName();
   private Context context;
  String bucket = "examplebucket-1250000000"; //存储桶,格式 BucketName-APPID, 替换为您的 bucket
  String region = Region.AP_Guangzhou.getRegion(); //存储桶所在地域, 填写您的 bucket 所在的地域
  private CosXmlService cosXmlService;
   private Handler mainHandler;
  private boolean isTriedOnce = false; //是否已重传过,避免无限制重传
  private final int MESSAGE_RETRY = 1;
   public ResumeHelper(Context context){
      this.context = context;
      this.mainHandler = new Handler(context.getMainLooper()){
          @Override
          public void handleMessage(Message msg) {
              super.handleMessage(msg);
              switch (msg.what){
                  case MESSAGE_RETRY:
                      /** 已重传过 */
                      if(isTriedOnce)return;
                      isTriedOnce = true;
                      Parameter parameter = (Parameter) msg.obj;
                      /** 再次上传 */
                      upload(parameter.srcPath, parameter.cosPath, parameter.uploadId, parameter.sliceSize);
                      break;
              }
          }
      };
      initCosXml();
  }
   /**
   * 初始化 CosXmlService
   */
  private void initCosXml(){
      /** 初始化 CosXmlServiceConfig */
      CosXmlServiceConfig cosXmlServiceConfig = new CosXmlServiceConfig.Builder()
              .setDebuggable(true)
              .isHttps(true)
              .setRegion(region)
              .builder();
       //此处为了方便测试,使用了永久密钥,实际应用中建议使用临时密钥
      String secretId = "COS_SECRETID"; //填写您的 云 API 密钥 SecretId
      String secretKey = "COS_SECRETKEY"; //填写您的 云 API 密钥 SecretKey
      /** 初始化 密钥信息 */
      QCloudCredentialProvider qCloudCredentialProvider = new ShortTimeCredentialProvider(secretId, secretKey, 6000);
       /** 初始化 CosXmlService */
      cosXmlService = new CosXmlService(context, cosXmlServiceConfig, qCloudCredentialProvider);
  }
   /**
   * 上传
   * @param srcPath 本地文件路径
   * @param cosPath 存储在 COS 上的路径
   * @param uploadId 是否续传,若无,则为 null
   * @param sliceSize 分块上传时,设置的分块块大小
   */
  public void upload(final String srcPath, final String cosPath, final String uploadId, long sliceSize){
       /** 设置分块上传时,分块块的大小 */
      TransferConfig transferConfig = new TransferConfig.Builder()
              .setSliceSizeForUpload(sliceSize)
              .build();
      /** 初始化TransferManager */
      TransferManager transferManager = new TransferManager(cosXmlService, transferConfig);
      /** 开始上传: 若 uploadId != null,则可以进行续传 */
      final COSXMLUploadTask uploadTask = transferManager.upload(bucket, cosPath, srcPath, uploadId);
      /** 显示任务状态信息 */
      uploadTask.setTransferStateListener(new TransferStateListener() {
          @Override
          public void onStateChanged(TransferState state) {
              Log.d(TAG, "upload task state: " + state.name());
          }
      });
      /** 显示任务上传进度 */
      uploadTask.setCosXmlProgressListener(new CosXmlProgressListener() {
          @Override
          public void onProgress(long complete, long target) {
              Log.d(TAG, "upload task progress: " + complete + "/" + target);
          }
      });
      /** 显示任务上传结果 */
      uploadTask.setCosXmlResultListener(new CosXmlResultListener() {
          /** 任务上传成功 */
          @Override
          public void onSuccess(CosXmlRequest request, CosXmlResult result) {
              COSXMLUploadTask.COSXMLUploadTaskResult uploadTaskResult = (COSXMLUploadTask.COSXMLUploadTaskResult) result;
              Log.d(TAG, "upload task success: " + uploadTaskResult.printResult());
          }
           /** 任务上传失败 */
          @Override
          public void onFail(CosXmlRequest request, CosXmlClientException exception, CosXmlServiceException serviceException) {
              Log.d(TAG, "upload task failed: " + (exception == null ? serviceException.getMessage() :
                      (exception.errorCode + "," + exception.getMessage())));
              if(exception != null){
                  /** 若是因为网络导致失败, 则可尝试将分块大小设置为100KB再运行一遍*/
                  if(exception.errorCode == ClientErrorCode.IO_ERROR.getCode()
                          || exception.errorCode == ClientErrorCode.POOR_NETWORK.getCode()){
                      Log.d(TAG, "upload task try again");
                      Message msg = mainHandler.obtainMessage();
                      msg.what = MESSAGE_RETRY;
                      Parameter parameter = new Parameter();
                      parameter.cosPath = cosPath;
                      parameter.srcPath = srcPath;
                      parameter.uploadId = uploadTask.getUploadId();
                      parameter.sliceSize = 100 * 1024L;
                      msg.obj = parameter;
                      mainHandler.sendMessage(msg);
                  }
              }
          }
      });
  }
   private static class Parameter{
      private String cosPath;
      private String srcPath;
      private String uploadId;
      private long sliceSize;
  }
}

iOS SDK

下面举例在弱网络环境中,使用分块上传对象的示例代码:

  QCloudCOSXMLUploadObjectRequest* put = [QCloudCOSXMLUploadObjectRequest new];
  NSURL* url = [NSURL fileURLWithPath:@"filePathURL"];
  put.object = @"text.txt";
  put.bucket = self.bucket;
  put.body =  url;
  [put setSendProcessBlock:^(int64_t bytesSent, int64_t totalBytesSent, int64_t totalBytesExpectedToSend) {
      NSLog(@"upload %lld totalSend %lld aim %lld", bytesSent, totalBytesSent, totalBytesExpectedToSend);
  }];
  [put setFinishBlock:^(QCloudUploadObjectResult *result, NSError *error) {
      /**
       1. 如果是请求超时,则可能是网络过慢导致的,可以从 error 中得到续传相关的信息 resumeData(存储在 QCloudUploadResumeDataKey 字段中)
       2. 调用 QCloudCOSXMLUploadObjectRequest的requestWithRequestData 传入 resumeData,重新生成一个 request。
       2. 根据需要通过 QCloudCOSXMLUploadObjectRequest 的 sliceSize 重新设置分块大小
       3. 开始上传
       */
      if (error.code == -1001) {
          NSData *resumeData =error.userInfo[QCloudUploadResumeDataKey];
          if (resumeData) {
              QCloudCOSXMLUploadObjectRequest* request = [QCloudCOSXMLUploadObjectRequest   requestWithRequestData:resumeData];
              request.sliceSize = 100*1024;
              [request setFinishBlock:^(QCloudUploadObjectResult* outputObject, NSError *error) {
                  NSLog(@"result: %@",outputObject);
              }];

              [request setSendProcessBlock:^(int64_t bytesSent, int64_t totalBytesSent, int64_t totalBytesExpectedToSend) {
                  NSLog(@"upload %lld totalSend %lld aim %lld", bytesSent, totalBytesSent, totalBytesExpectedToSend);
              }];
              [[QCloudCOSTransferMangerService defaultCOSTransferManager] UploadObject:request];
          }
      }
  }];
 [[QCloudCOSTransferMangerService defaultCOSTransferManager] UploadObject:put];
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