Question

asp.net中如何写下载代码

我想要详细的说明，谢谢打家了哈！

Answer 1

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.Text;
using System.IO;

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
DownloadClass dd = new DownloadClass();
dd.StrUrl = "http://127.0.0.1/UI.rar";
dd.StrFileName="C:\\1.rar";
dd.DownloadFile();
Response.Write(dd.strError);
}
//测试用线程1断点续传下载网络上的文件到本地电脑
public class DownloadClass
{
public string StrUrl;//文件下载网址
public string StrFileName;//下载文件保存地址
public string strError;//返回结果
public long lStartPos = 0; //返回上次下载字节
public long lCurrentPos = 0;//返回当前下载字节
public long lDownloadFile;//返回当前下载文件长度

public void DownloadFile()
{
System.IO.FileStream fs;
if (System.IO.File.Exists(StrFileName))
{
fs = System.IO.File.OpenWrite(StrFileName);
lStartPos = fs.Length;
fs.Seek(lStartPos, System.IO.SeekOrigin.Current);
//移动文件流中的当前指针
}
else
{
fs = new System.IO.FileStream(StrFileName, System.IO.FileMode.Create);
lStartPos = 0;
}

//打开网络连接
try
{
System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(StrUrl);
long length = request.GetResponse().ContentLength;
lDownloadFile = length;
if (lStartPos > 0)
request.AddRange((int)lStartPos); //设置Range值

//向服务器请求，获得服务器回应数据流
System.IO.Stream ns = request.GetResponse().GetResponseStream();

byte[] nbytes = new byte[512];
int nReadSize = 0;
nReadSize = ns.Read(nbytes, 0, 512);
while (nReadSize > 0)
{
fs.Write(nbytes, 0, nReadSize);
nReadSize = ns.Read(nbytes, 0, 512);
lCurrentPos = fs.Length;
}

fs.Close();
ns.Close();
strError = "下载完成";

}
catch (Exception ex)
{
fs.Close();
strError = "下载过程中出现错误:" + ex.ToString();
}

}
}
}