文件下载与处理-优快云博客

本文链接：https://blog.youkuaiyun.com/wsd309/article/details/1660952

本文介绍了一个文件下载过程的实现细节，包括使用HTTP POST请求发送文件名，并从服务器接收文件数据，同时提供了用户取消操作的功能。

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private   void   DownLoadFile()
                  {
                          Trans_Transing   =   true;
                          string   strFileName   =   Trans_szFileName;
                          try
                          {
                                  string   strUU   =   @" http://*.*.*/*.asp";
                                  Trans_szTextShow   =   "正在建立连接...";
                                  HttpWebRequest   myRequest   =   (HttpWebRequest)WebRequest.Create(strUU);
                                  myRequest.Method   =   "POST";
                                  string   strData   =   strFileName;
                                  myRequest.ContentLength   =   strData.Length;
                                  Stream   newStream   =   myRequest.GetRequestStream();
                                  if   (Trans_endThread)               //用户结束
                                  {
                                          if   (MessageBox.Show("正在发送数据,您确定要取消当前操作?",   "提醒",   MessageBoxButtons.YesNo,   MessageBoxIcon.Question,   MessageBoxDefaultButton.Button1)   ==   DialogResult.Yes)
                                          {
                                                  newStream.Close();
                                                  Trans_Transing   =   false;
                                                  return;
                                          }
                                  }
                                  Trans_szTextShow   =   "连接成功,正在发送数据";
                                  ASCIIEncoding   encoding   =   new   ASCIIEncoding();
                                  byte[]   byte1   =   encoding.GetBytes(strData);
                                  newStream.Write(byte1,   0,   byte1.Length);
                                  newStream.Close();
                                  if   (Trans_endThread)               //用户结束
                                  {
                                          if   (MessageBox.Show("正在等待网络回复,您确定要取消当前操作?",   "提醒",   MessageBoxButtons.YesNo,   MessageBoxIcon.Question,   MessageBoxDefaultButton.Button1)   ==   DialogResult.Yes)
                                          {
                                                  Trans_Transing   =   false;
                                                  return;
                                          }
                                  }
                                  Trans_szTextShow   =   "发送成功,等待回应";
                                  WebResponse   response   =   null;
                                  try
                                  {
                                          response   =   myRequest.GetResponse();
                                  }
                                  catch   (Exception   error)
                                  {
                                          MessageBox.Show(error.Message);
                                  }
                                  Stream   ReceiveStream   =   response.GetResponseStream();
                                  Encoding   encode   =   Encoding.Default;
                                  StreamReader   readStream   =   new   StreamReader(ReceiveStream,   encode);
                                  char[]   read   =   new   char[256];
                                  Trans_szTextShow   =   "";
                                  Trans_MaxaProcessbar   =   (int)(response.ContentLength   /   256);

                                  int   count   =   readStream.Read(read,   0,   256);
                                  string   str   =   new   string(read,   0,   count);
                                  Trans_aProcessbar++;
                                  Trans_strTempFileData   =   str;
                                  while   (count   >   0)
                                  {
                                          if   (Trans_endThread)               //用户结束
                                          {
                                                  if   (MessageBox.Show("正在下载数据,您确定要取消下载操作?",   "提醒",   MessageBoxButtons.YesNo,   MessageBoxIcon.Question,   MessageBoxDefaultButton.Button1)   ==   DialogResult.Yes)
                                                  {
                                                          readStream.Close();
                                                          ReceiveStream.Close();
                                                          Trans_Transing   =   false;
                                                          return;
                                                  }
                                          }
                                          count   =   readStream.Read(read,   0,   256);
                                          if   (count   <=   0)
                                                  break;
                                          Trans_aProcessbar++;
                                          string   st   =   new   string(read,   0,   count);
                                          Trans_strTempFileData   +=   st;
                                  }
                                  readStream.Close();
                                  ReceiveStream.Close();

                          }
                          catch   (Exception   error)
                          {
                                  MessageBox.Show(error.Message);
                                  Trans_Transing   =   false;
                                  return;
                          }
                          if   (Trans_endThread)               //用户结束
                          {
                                  if   (MessageBox.Show("文件下载,您确定要取消保存操作?",   "提醒",   MessageBoxButtons.YesNo,   MessageBoxIcon.Question,   MessageBoxDefaultButton.Button1)   ==   DialogResult.Yes)
                                  {
                                          Trans_Transing   =   false;
                                          return;
                                  }
                          }

                          Trans_szTextShow   =   "文件传输完毕,正在保存";

                          Trans_Ret   =   WriteFile(strFileName);
                          Trans_Transing   =   false;
                  }