C#怎么实现文件下载功能的四种方法

using System;  
using System.Data;  
using System.Configuration;  
using System.Web;  
using System.Web.Security;  
using System.Web.UI;  
using System.Web.UI.WebControls;  
using System.Web.UI.WebControls.WebParts;  
using System.Web.UI.HtmlControls;  
using System.IO;  
  
public partial class _Default : System.Web.UI.Page   
{  
    protected void Page_Load(object sender, EventArgs e)  
    {  
  
    }  
  
    //TransmitFile实现下载  
    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";  
        string FileName = "test.doc";  
        //使用UTF-8对文件名进行编码  
        Response.AppendHeader("Content-Disposition", "attachment;filename="" + HttpUtility.UrlEncode(FileName, System.Text.Encoding.UTF8) + """);  
        Response.ContentType = "application/octet-stream";  
        Response.AddHeader("Content-Disposition", "attachment;filename=" + FileName);  
        string filename = Server.MapPath("../ReportTemplate/test.doc");  
        Response.TransmitFile(filename);  
    }  
  
    //WriteFile实现下载  
    protected void Button2_Click(object sender, EventArgs e)  
    {  
         /* 
         using System.IO;          
         */  
        string fileName = "test.doc";//客户端保存的文件名  
        string filePath = Server.MapPath("../ReportTemplate/test.doc");//路径  
        FileInfo fileInfo = new FileInfo(filePath);  
        Response.Clear();  
        Response.ClearContent();  
        Response.ClearHeaders();  
        Response.AddHeader("Content-Disposition", "attachment;filename="" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8) + """);  
        Response.AddHeader("Content-Length", fileInfo.Length.ToString());  
        Response.AddHeader("Content-Transfer-Encoding", "binary");  
        Response.ContentType = "application/octet-stream";  
        Response.WriteFile(fileInfo.FullName);  
        Response.Flush();  
        Response.End();  
    }  
  
    //WriteFile分块下载  
    protected void Button3_Click(object sender, EventArgs e)  
    {  
        string fileName = "test.doc";//客户端保存的文件名  
        string filePath = Server.MapPath("../ReportTemplate/test.doc");//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, System.Text.Encoding.UTF8));  
            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 = "test.doc";//客户端保存的文件名  
        string filePath = Server.MapPath("../ReportTemplate/test.doc");//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();  
    }  
}  

　　

System.Diagnostics.Process.Start(url);