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需求：下载站点目录下DownLoad文件夹中的logo.zip

前端HTML代码部分：

<div>1.通过超链接下载：<a href="../DownLoadFiles/logo.zip">点击下载</a><br /><!-- 一样的效果 -->1.通过超链接下载：<a href="/DownLoadFiles/logo.zip">点击下载</a><br />2.通过Response对象的TransmitFile方法（这个方法下载下来的是整个网页：DownLoadFile.aspx）：<asp:Button runat="server" ID="btnDownload" Text="点击下载" OnClick="btnDownload_Click" /><br />3.WriteFile实现下载：<asp:Button runat="server" ID="btnDownload2" Text="点击下载" OnClick="btnDownload_Click2" /><br />4.WriteFile分块下载：<asp:Button runat="server" ID="btnDownload3" Text="点击下载" OnClick="btnDownload_Click3" /><br />5.字符流方式下载文件：<asp:Button runat="server" ID="btnDownload4" Text="点击下载" OnClick="btnDownload_Click4" /></div>

后端类部分：

第一种方法：

超链接的形式下载：html代码中已实现

第二种方法：

 protected void btnDownload_Click(object sender, EventArgs e){//这种方法会把整个网页下载下来//TransmitFile实现下载/*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：*///文件下载，所以文件头也含有zipResponse.ContentType = "application/x-zip-compressed";Response.AddHeader("Content-Disposition", "attachment:filename=logo.zip");//找到文件的绝对路径string filename = Server.MapPath(".") + "/DownLoadFiles/logo.zip";Response.TransmitFile(filename);}

第三种方法：

protected void btnDownload_Click2(object sender, EventArgs e){//WriteFile实现下载string fileName = "logo.zip";//客户端保存的文件名string filePath = Server.MapPath(".") + "/DownLoadFiles/logo.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();}

第四种方法：

 protected void btnDownload_Click3(object sender, EventArgs e){//WriteFile分块下载string fileName = "logo.zip";//客户端保存的文件名string filePath = Server.MapPath(".") + "/DownLoadFiles/logo.zip";//路径System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);if (fileInfo.Exists == true){const long ChunkSize = 409600;//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/x-zip-compressed";      //可以改成zip哦Response.ContentType = "application/octet-stream";   //也可以不改哦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();}}

第五种方法：

  protected void btnDownload_Click4(object sender, EventArgs e){//字符流方式下载文件string fileName = "logo.zip";//客户端保存的文件名string filePath = Server.MapPath(".") + "/DownLoadFiles/logo.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();}
}

注意：如果出现无法进行下载，提示logo.zip被另一个文件占用的时候，可以直接关闭项目，再重启项目。问题就会得到解决。
参考链接：https://blog.csdn.net/llftc/article/details/7099753