asp.net C#实现下载文件的六种方法实例

protected void button1_click(object sender, eventargs e)
  {
  /*
  微软为response对象提供了一个新的方法transmitfile来解决使用response.binarywrite
  下载超过400mb的文件时导致aspnet_wp.exe进程回收而无法成功下载的问题。
  代码如下：
  */

  response.contenttype = "application/x-zip-compressed";
  response.addheader("content-disposition", "attachment;filename=z.zip");
  string filename = server.mappath("download/aaa.zip");
  response.transmitfile(filename);
  }

  //writefile实现下载
  protected void button2_click(object sender, eventargs e)
  {
  /*
  using system.io;

  */

  string filename ="aaa.zip";//客户端保存的文件名
  string filepath=server.mappath("download/aaa.zip");//路径

  fileinfo fileinfo = new fileinfo(filepath);
  response.clear();
  response.clearcontent();
  response.clearheaders();
  response.addheader("content-disposition", "attachment;filename=" + filename);
  response.addheader("content-length", fileinfo.length.tostring());
  response.addheader("content-transfer-encoding", "binary");
  response.contenttype = "application/octet-stream";
  response.contentencoding = system.text.encoding.getencoding("gb2312");
  response.writefile(fileinfo.fullname);
  response.flush();
  response.end();
  }

  //writefile分块下载
  protected void button3_click(object sender, eventargs e)
  {

  string filename = "aaa.zip";//客户端保存的文件名
  string filepath = server.mappath("download/aaa.zip");//路径

  system.io.fileinfo fileinfo = new system.io.fileinfo(filepath);

  if (fileinfo.exists == true)
  {
  const long chunksize = 102400;//100k 每次读取文件，只读取100ｋ，这样可以缓解服务器的压力
  byte[] buffer = new byte[chunksize];

  response.clear();
  system.io.filestream istream = system.io.file.openread(filepath);
  long datalengthtoread = istream.length;//获取下载的文件总大小
  response.contenttype = "application/octet-stream";
  response.addheader("content-disposition", "attachment; filename=" + httputility.urlencode(filename));
  while (datalengthtoread > 0 && response.isclientconnected)
  {
  int lengthread = istream.read(buffer, 0, convert.toint32(chunksize));//读取的大小
  response.outputstream.write(buffer, 0, lengthread);
  response.flush();
  datalengthtoread = datalengthtoread - lengthread;
  }
  response.close();
  }
  }

  //流方式下载
  protected void button4_click(object sender, eventargs e)
  {
  string filename = "aaa.zip";//客户端保存的文件名
  string filepath = server.mappath("download/aaa.zip");//路径

  //以字符流的形式下载文件
  filestream fs = new filestream(filepath, filemode.open);
  byte[] bytes = new byte[(int)fs.length];
  fs.read(bytes, 0, bytes.length);
  fs.close();
  response.contenttype = "application/octet-stream";
  //通知浏览器下载文件而不是打开
  response.addheader("content-disposition", "attachment; filename=" + httputility.urlencode(filename, system.text.encoding.utf8));
  response.binarywrite(bytes);
  response.flush();
  response.end();

  }