通过HTTPS

Question

我一直在使用WinHTTP和WinInet处理HTTP客户端，最近考虑过切换到POCO，因为它为HTTP实现提供了最佳API。

我确实让它工作，但问题是我想通过定期查询流或通过某些事件处理来了解文件的下载进度。

开始搜索可以执行此操作的API，然后遇到了Http upload with progress info, in C++ (Poco/Boost)，其中讨论了使用CountingOutputStream获取文件上载方案的进度。我觉得这是不完整的，并没有按照我的预期那样做，根本没有使用CountingStream的实际实现。

我开始知道可以通过CountingInputStream实现，但我不知道如何使用HttpStreamFactory的公开调用返回的流来实现。是否可以使用多个块读取流？或定期查询读取的数据量，以便我可以通知用户界面？

这是我的代码：

bool HttpClientConnection::DownloadFile ( const std::string& file_url, const std::string file_location )
{

         try
         {
               std::string complete_page_url = "";
               std::ofstream file_stream;
               std::unique_ptr<std::istream> pStr       = nullptr;


               if (isSecureConnection)
               {
                    complete_page_url = "https://";
               }
               else
               {
                    complete_page_url = "http://";
               }


               {
                    complete_page_url = serverHostName + file_url;// assuming the file url itself will contain leading forward slash
               }


             // Create the URI from the URL to the file.
             URI uri(complete_page_url);

               //std::auto_ptr<std::istream>pStr(URIStreamOpener::defaultOpener().open(uri);
            //StreamCopier::copyStream(*pStr.get(), std::cout);

             if (isSecureConnection)
             {
                  std::unique_ptr<HTTPSStreamFactory> https_stream_factory = nullptr;

                  if (_buseProxy)
                  {
                       https_stream_factory = std::unique_ptr<HTTPSStreamFactory>(new HTTPSStreamFactory(proxyHostName, proxyPort, getProxyUserName(),  getProxyPassword()));
                  }
                  else
                  {
                       https_stream_factory = std::unique_ptr<HTTPSStreamFactory>(new HTTPSStreamFactory());
                  }

                  if (https_stream_factory)
                  {
                      pStr  = std::unique_ptr<std::istream>(https_stream_factory->open(uri));
                  }
              }
              else
              {
                  std::unique_ptr<HTTPStreamFactory> http_stream_factory = nullptr;

                  if (_buseProxy)
                  {
                      http_stream_factory = std::unique_ptr<HTTPStreamFactory>(new HTTPStreamFactory(proxyHostName, proxyPort, getProxyUserName(),  getProxyPassword()));
                  }
                  else
                  {
                      http_stream_factory   = std::unique_ptr<HTTPStreamFactory>(new HTTPStreamFactory());
                  }

                  if (http_stream_factory)
                  {
                      pStr  = std::unique_ptr<std::istream>(http_stream_factory->open(uri));
                  }
            }

            if (pStr)
            {
                  file_stream.open(file_location, ios::out | ios::trunc | ios::binary);

                  StreamCopier::copyStream(*pStr.get(), file_stream);

                  file_stream.close();
             }

           return true;
}
catch (Exception& exc)
{
    if (httpLogger)
    {
                                         httpLogger->log(dcLogger::LOG_INFO, "HttpClient:: Exception in DownloadFile , error code: %d", exc.code());
    }
}

return false;

}

Answer 1

将fileoutput流对象传递给CountingOutputStream，并以计数输出流作为参数启动计时器。定期调用Timer，直到数据传输完成，获取写入的字节数，并通知注册该事件的人。那很有用！。

shared_ptr<CountingOutputStream> cout_stream = shared_ptr<CountingOutputStream>(new CountingOutputStream(file_stream));

if (callback && callback_interval_in_millis > 0)
{
    shared_ptr<FileProgressHandler> file_progress = shared_ptr<FileProgressHandler>(new FileProgressHandler(cout_stream, file_size, callback));

    if (file_progress)
    {
        TimerCallback<FileProgressHandler> callback(*(file_progress.get()), &FileProgressHandler::onTimer);

        timer = shared_ptr<Timer>(new Timer(0, callback_interval_in_millis));

        if (timer)
        {
            timer->start(callback);
        }
    }

    StreamCopier::copyStream(*pStr.get(), *cout_stream);

    if (timer)
    {
         timer->stop();
    }
}

void onTimer(Timer& timer)
{
    try
    {
        if (progress_callback)
        {
            int data_processed = 0;

            counting_io_stream ? data_processed = counting_io_stream->chars() : __noop;

            if (data_processed != total_processed_data)
            {
                total_processed_data = data_processed;

                int percent     = (100 * total_processed_data) / file_size;

                progress_callback(percent);
            }
        }
    }
    catch(const std::bad_function_call& e) 
    {

    }
    catch(const std::bad_weak_ptr& e)
    {

    }
    catch(const std::exception& e)
    {

    }
}