C#,Asp.Net多线程断点续传下载

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;
using System.IO;

namespace BreakDownload
{
   public partial class frmBreakDownload : Form
   {
      private DataTable _dtFileInfos = null;
      private DataSet _dsFileInfo = null;
      private DownloadThread _CurrDownload = null;
      
      private const string FILE_NAME = "Download.Log";
      
      public frmBreakDownload()
      {
         InitializeComponent();
      }
      
      private void frmBreakDownload_Load(object sender, EventArgs e)
      {
         if (!File.Exists(FILE_NAME))
         {
            _dsFileInfo=new DataSet();
            
            this.CreateTable();
         }
      }
      
      private void btnStop_Click(object sender, EventArgs e)
      {
         this.StopTask();
      }
      
      private void btnStart_Click(object sender, EventArgs e)
      {
         this.StartTask();
      }
      
      private void btnRestart_Click(object sender, EventArgs e)
      {
         this.RestartTask();
      }
      
      public void StartTask()
      {
         //Create new row to save download file info
         DataRow dr = _dtFileInfos.NewRow();
         _dtFileInfos.Rows.Add(dr);
         
         //Create object
         _CurrDownload = new DownloadThread(
         txtURL.Text,
         "",
         @"c:\" + DateTime.Now.ToString("yyyyMMddHHmmss"),
         dr,
         1);
         
         _CurrDownload.Finished += new ThreadFinishedHandler(Finished);
         _CurrDownload.DataReceived = new DataReceivedEventHandler(DataReceived);
         
         _CurrDownload.Start();
      }
      
      
      public void RestartTask()
      {
         // Read thread info
         DataSet dsThreadInfo = new DataSet();
         
         foreach (DataRow dr in _dtFileInfos.Rows)
         {
            dsThreadInfo.ReadXml(dr["CreatedTime"].ToString() + ".xml");
         }
         
         if (dsThreadInfo.Tables.Count <= 0) return;
         
         // Init download object
         // Restart to download
         _CurrDownload = new DownloadThread(_dtFileInfos.Rows[0], dsThreadInfo.Tables[0]);
         _CurrDownload.Finished += new ThreadFinishedHandler(Finished);
         _CurrDownload.DataReceived = new DataReceivedEventHandler(DataReceived);
         _CurrDownload.Start();
         btnStop.Enabled = true;
      }
      
      public void StopTask()
      {
         // Set stop message to all
         _CurrDownload.Stop();
         
         // Save log file
         _dtFileInfos.AcceptChanges();
         _dsFileInfo.WriteXml(FILE_NAME);
         foreach (DataRow dr in _dtFileInfos.Rows)
         {
            DataSet dsThreadInfo = null;
            
            DataTable dt = _CurrDownload.ThreadInfo;
            
            if (dt.DataSet == null)
            {
               dsThreadInfo = new DataSet();
               dsThreadInfo.Tables.Add(_CurrDownload.ThreadInfo);
            }
            else
            dsThreadInfo = dt.DataSet;
            
            dsThreadInfo.WriteXml(dr["CreatedTime"].ToString() + ".xml");
         }
      }
      
      private void LoadFile()
      {
         _dsFileInfo = new DataSet();
         if (!File.Exists(FILE_NAME))
         {
            CreateTable();
            return;
         }
         
         _dsFileInfo.ReadXml(FILE_NAME);
         
         if (_dsFileInfo.Tables.Count == 0)
         this.CreateTable();
         else
         _dtFileInfos = _dsFileInfo.Tables["DownloadFileInfo"];
      }
      
      private void CreateTable()
      {
         _dtFileInfos = new DataTable("DownloadFileInfo");
         _dtFileInfos.Columns.Add("RequestURL", typeof(string));
         _dtFileInfos.Columns.Add("ResponseURL", typeof(string));
         _dtFileInfos.Columns.Add("FileName", typeof(string));
         _dtFileInfos.Columns.Add("TotalSize", typeof(int));
         _dtFileInfos.Columns.Add("BlockLeftSize", typeof(int));
         _dtFileInfos.Columns.Add("CreatedTime", typeof(string));
         _dsFileInfo.Tables.Add(_dtFileInfos);
      }
      
      private void DataReceived(DownLoadEventArgs e)
      {
         _CurrDownload.UpdateDownloadInfo(e.ThreadNO, e.StartPosition, e.ReadCount);
         
         Debug.WriteLine(string.Format("Thread NO:{0} read {2} bytes from {1} postion!",
         e.ThreadNO,
         e.StartPosition,
         e.ReadCount));
      }
      
      private void Finished()
      {
         _dtFileInfos.AcceptChanges();
         _dsFileInfo.WriteXml(FILE_NAME); //your log file
         btnStop.Enabled = false;
         btnRestart.Enabled = false;
         btnDownload.Enabled = true;
         
         MessageBox.Show("Download finished");
      }
      
   }
}

开始下载...

Thread NO:0 begins to download!
Thread NO:0 call function named DownloadData!
Thread NO:0 reads data!
Thread NO:0 writes data!
Thread NO:0 writes 3768 data!
Thread NO:0 send callback info!
Thread NO:0 read 3768 bytes from 0 postion!
Thread NO:0 reads data!
Thread NO:0 writes data!
Thread NO:0 writes 65536 data!
Thread NO:0 send callback info!

暂停下载...

The thread 0x13e0 has exited with code 0 (0x0).
Thread NO:0 is stopped!
The thread 0xefc has exited with code 0 (0x0).

暂停后重新下载...

Thread NO:0 begins to download!
Thread NO:0 call function named DownloadData!
Thread NO:0 reads data!
Thread NO:0 writes data!
Thread NO:0 writes 3763 data!
Thread NO:0 send callback info!