.Net/C#: 实现支持断点续传多线程下载的 Http Web 客户端工具类 (C# DIY Ht

/* .Net/C#: 实现支持断点续传多线程下载的 Http Web 客户端工具类 (C# DIY HttpWebClient)
* Reflector 了一下 System.Net.WebClient ,重载或增加了若干:
* DownLoad、Upload 相关方法!
* DownLoad 相关改动较大!
* 增加了 DataReceive、ExceptionOccurrs 事件!
* 了解服务器端与客户端交互的 HTTP 协议参阅:
* 使文件下载的自定义连接支持 FlashGet 的断点续传多线程链接下载! JSP/Servlet 实现!
* http://blog.111com.net/playyuer/archive/2004/08/02/58430.aspx
* 使文件下载的自定义连接支持 FlashGet 的断点续传多线程链接下载! C#/ASP.Net 实现!
* http://blog.111com.net/playyuer/archive/2004/08/02/58281.aspx
*/
namespace Microshaoft.Utils
{
using System;
using System.IO;
using System.Net;
using System.Text;
using System.Security;
using System.Threading;
using System.Collections.Specialized;

///

/// 记录下载的字节位置
///

public class DownLoadState
{
private string _FileName;
private string _AttachmentName;
private int _Position;
private string _RequestURL;
private string _ResponseURL;
private int _Length;
private byte[] _Data;
public string FileName
{
get
{
return _FileName;
}
}
public int Position
{
get
{
return _Position;
}
}
public int Length
{
get
{
return _Length;
}
}
public string AttachmentName
{
get