sivelrlight 结合asp.net用于大文件下载

来源：互联网发布：林清轩芦荟胶知乎编辑：程序博客网时间：2024/04/28 14:15

一、在web项目下添加一个“一般处理程序”

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.IO;namespace Silverlightdownload.Web{    /// <summary>    /// FileDownLoader 的摘要说明    /// </summary>    public class FileDownLoader : IHttpHandler    {        private long ChunkSize = 20;//100K 每次读取文件，只读取100Ｋ，这样可以缓解服务器的压力        public void ProcessRequest(HttpContext context)        {                   // String fileName = context.Request.QueryString["fileName"]; //客户端传来的文件名              //String filePath = context.Server.MapPath("Files/" + fileName); //要下载文件的路径               String filePath = context.Request.QueryString["filePath"];            String fileName = filePath.Substring(filePath.LastIndexOf('/') + 1);            System.IO.Stream iStream = null;            byte[] buffer = new byte[ChunkSize]; // Buffer to read 10K bytes in chunk:            int lengthRead;//读取的大小            long dataLengthToRead;//获得下载文件的总大小            context.Response.Clear();            System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);                                                  if (fileInfo.Exists == true)                {                           try                    {                    iStream = System.IO.File.OpenRead(filePath);                        dataLengthToRead = iStream.Length;                    context.Response.ContentType = "application/octet-stream";                    //通知浏览器下载文件而不是打开                    context.Response.AddHeader("Content-Disposition", "attachment;  filename=" + fileName);                    UserLog.WriteErrLog("dataLengthToRead", dataLengthToRead.ToString());                                           while (dataLengthToRead > 0 && context.Response.IsClientConnected)                     {                        if (context.Response.IsClientConnected)                        {                                lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));                            context.Response.OutputStream.Write(buffer, 0, lengthRead);                            context.Response.Flush();                            dataLengthToRead = dataLengthToRead - lengthRead;                            UserLog.WriteErrLog("dataLengthToRead", dataLengthToRead.ToString());                        }                        else {                            dataLengthToRead = -1;                        }                                               }                  }                 catch (Exception ex)                        {                            UserLog.WriteErrLog("LocalDownloadError", ex.ToString());                            return;                        }                 finally                       {                            if (iStream != null)                            {                                //Close the file.                                iStream.Close();                            }                        }                   context.Response.Clear();//注意是clear（），不是close（），close（）对空文件报错                   context.Response.End();            }                       }               public bool IsReusable        {            get            {                return false;            }        }    }}

二、在页面中添加一个HyperlinkButton控件

<UserControl x:Class="Silverlightdownload.MainPage"    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"    mc:Ignorable="d"    d:DesignHeight="300" d:DesignWidth="400">    <Grid x:Name="LayoutRoot" Background="White">        <HyperlinkButton Name="hyLinkDownLoad" Content="下载文件" HorizontalAlignment="Left" Height="17" Margin="67,83,0,0" VerticalAlignment="Top" Width="73" Click="hyLinkDownLoad_Click" Cursor="Hand"/>    </Grid></UserControl>

三、添加点击事件

  private void hyLinkDownLoad_Click(object sender, RoutedEventArgs e)        {            string fileName = "C:\\Users\\dell\\Desktop\\ceshi\\hudd1.txt";//要下载的文件名              Uri uri = new Uri("/FileDownLoader.ashx?filePath=" + fileName, UriKind.Relative);            this.hyLinkDownLoad.NavigateUri = uri;        }

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