HTTP协议断点续传

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;

namespace HttpDemo
{
class Program
{
//需要下载的路径
static string url = "http://www.aseoe.com/demo/api/jquery_aseoe_001.zip";
//获取文件全称
static string fileName = Path.GetFileName(url);
//保存路径
static string localPath = "D:\HttpCeShi\" + fileName;
//未下载完后面加.temp后缀名
static string tempPath = localPath + ".temp";
//偏移量（断点）
static int pos;

static void Main(string[] args)
{
DownLoad();
Console.ReadLine();
}
public static void DownLoad()
{
//如果存在要更新的文件就结束
if (File.Exists(localPath))
return;

Stream localfs = null;
//如果不存在未上传完文件（需断点续传文件）
if (File.Exists(tempPath))
{
localfs = new FileStream(tempPath, FileMode.Open);
}

else
{
localfs = new FileStream(tempPath, FileMode.Create);
}
//获取断点
pos = (int)localfs.Length;

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Headers.Add("Accept-Charset", "GBK,utf-8");
request.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)";
request.Method = "GET";
request.Timeout = 30000;
//文件总长度单位（B）
long total = request.GetResponse().ContentLength;
Console.WriteLine("总长度为：" + total);
if (pos > 0)
request.AddRange(pos);//偏移到断点

HttpWebResponse responseResult = (HttpWebResponse)request.GetResponse();
using (Stream stream = responseResult.GetResponseStream())
{
byte[] buffer = new byte[total - pos];

int readSize = stream.Read(buffer, 0, buffer.Length);
while (readSize > 0)
{
localfs.Write(buffer, 0, readSize);
readSize = stream.Read(buffer, 0, buffer.Length);
Console.WriteLine("已下载：" + localfs.Length);
}
localfs.Close();
File.Move(tempPath, localPath);//将临时文件改为正常文件后缀
Console.WriteLine("下载完成!!!");
}

}

}
}