ASP.NET 实现PDF文件下载

本文介绍了一种在ASP.NET中下载文件的方法。 方法一：可能是最简单的、最短的方式：

  Response.ContentType = "application/pdf";
  Response.AppendHeader("Content-Disposition", "attachment; filename=MyFile.pdf");
  Response.TransmitFile(Server.MapPath("~/Files/MyFile.pdf"));
  Response.End();

第一步是设置文档内容的类型，上面的例子是下载一个.PDF格式的文件。下面是最常用的一些文档内容类型：

.htm, .html     Response.ContentType = "text/HTML";

.txt    Response.ContentType = "text/plain";

.doc, .rtf, .docx    Response.ContentType = "Application/msword";

.xls, .xlsx    Response.ContentType = "Application/x-msexcel";

.jpg, .jpeg    Response.ContentType = "image/jpeg";

.gif    Response.ContentType =  "image/GIF";

.pdf    Response.ContentType = "application/pdf";

方法二：解决.PDF文件较大时，可能导致所下载的PDF文件无法打开的方案

     protected void Button1_Click(object sender, EventArgs e)
     {
         string path;
         try
         {
             path = Request.PhysicalApplicationPath + "/" + Session["pdfpath"].ToString() + "/PDF/" + Session["mlmc"].ToString() + ".pdf";
         }
         catch (Exception)
         {
             return;
         }
         System.IO.Stream iStream = null;
         byte[] buffer = new Byte[];
         int length;
         long dataToRead;
         string filename = Session["mlmc"].ToString() + ".pdf";  

         try
         {
             iStream = new System.IO.FileStream(path, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read);
             dataToRead = iStream.Length;
             Response.Clear();
             Response.ClearHeaders();
             Response.ClearContent();
             Response.ContentType = "application/pdf"; //文件类型
             Response.AddHeader("Content-Length", dataToRead.ToString());//添加文件长度，进而显示进度
             Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8));
             while (dataToRead > )
             {
                 if (Response.IsClientConnected)
                 {
                     length = iStream.Read(buffer, , );
                     Response.OutputStream.Write(buffer, , length);
                     Response.Flush();  

                     buffer = new Byte[];
                     dataToRead = dataToRead - length;
                 }
                 else
                 {
                     dataToRead = -;
                 }
             }  

         }
         catch (Exception ex)
         {
             Response.Write("文件下载时出现错误!");
         }
         finally
         {
             if (iStream != null)
             {
                 iStream.Close();
             }
             //结束响应，否则将导致网页内容被输出到文件，进而文件无法打开
             Response.End();
         }
     }  
  通过以上代码，可在浏览器中打开一个“打开/保存”对话框来下载并保存文件。