using System;using System.Collections;using System.Configuration;using System.Data;using System.Linq;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Xml.Linq;using System.Threading;using System.Net;using System.IO;namespace WebAppTest{    public partial class download : System.Web.UI.Page    {        protected void Page_Load(object sender, EventArgs e)        {            //断点下载大文件            //原理：使用多个线程将一个文件分成多个文件进行下载            MutilDownload();        }        public void MutilDownload()        {            int threadcount = 3;            int threadCompleteNum = 0;            string[] files = new string[threadcount];            int total = (int)GetDownloadFileSize();            int per = total / threadcount;            for (int i = 1; i <= threadcount; i++)            {                int from = (i - 1) * per+1;                int to = i * per;                if (i == 1)                {                    from = 0;                }                if (i == threadcount)                {                    to = total;                }                               string path = Server.MapPath("~/resource/video/");                if (!Directory.Exists(path))                {                    Directory.CreateDirectory(path);                }                int index = i;                Thread thread = new Thread(() =>                {                    HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("http://192.168.1.100:106/test/test.avi");                    request.Method = "get";                    request.AddRange(from, to);                    HttpWebResponse response = (HttpWebResponse)request.GetResponse();                    string filename = path + index + ".avi";                    files[index-1] = filename;                    using (FileStream fs = new FileStream(filename, FileMode.CreateNew))                    {                        byte[] buffer = new byte[5 * 1024 * 1024];                        int r;                        using (Stream stream = response.GetResponseStream())                        {                            while ((r = stream.Read(buffer, 0, buffer.Length)) != 0)                            {                                fs.Write(buffer, 0, r);                            }                        }                    }                    threadCompleteNum++;                    if (threadCompleteNum == threadcount)                    {                        //和并临时文件                        string allFilename = path + "all.avi";                        using (FileStream allFile = new FileStream(allFilename, FileMode.CreateNew))                        {                            for (int j = 0; j < files.Length; j++)                            {                                using (FileStream tempFile = new FileStream(files[j], FileMode.Open))                                {                                    byte[] tempBuffer = new byte[5 * 1024 * 1024];                                    int t;                                    while ((t = tempFile.Read(tempBuffer, 0, tempBuffer.Length)) != 0)                                    {                                        allFile.Write(tempBuffer, 0, t);                                    }                                }                                                           }                        }                        //删除临时文件                        foreach (var f in files)                        {                            if (File.Exists(f))                            {                                File.Delete(f);                            }                         }                    }                });                thread.IsBackground = true;                thread.Start();            }        }        //获取下载文件大小        public long GetDownloadFileSize()        {            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("http://192.168.1.100:106/test/test.avi");            request.Method = "get";            HttpWebResponse response = (HttpWebResponse)request.GetResponse();            return response.ContentLength;        }    }}