/* .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.csdn.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.csdn.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;

/// <summary>
/// 记录下载的字节位置
/// </summary>
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
{
return _AttachmentName;
}
}

public string RequestURL
{
get
{
return _RequestURL;
}
}

public string ResponseURL
{
get
{
return _ResponseURL;
}
}


public byte[] Data
{
get
{
return _Data;
}
}

internal DownLoadState(string RequestURL, string ResponseURL, string FileName, string AttachmentName, int Position, int Length, byte[] Data)
{
this._FileName = FileName;
this._RequestURL = RequestURL;
this._ResponseURL = ResponseURL;
this._AttachmentName = AttachmentName;
this._Position = Position;
this._Data = Data;
this._Length = Length;
}

internal DownLoadState(string RequestURL, string ResponseURL, string FileName, string AttachmentName, int Position, int Length, ThreadCallbackHandler tch)
{
this._RequestURL = RequestURL;
this._ResponseURL = ResponseURL;
this._FileName = FileName;
this._AttachmentName = AttachmentName;
this._Position = Position;
this._Length = Length;
this._ThreadCallback = tch;
}

internal DownLoadState(string RequestURL, string ResponseURL, string FileName, string AttachmentName, int Position, int Length)
{
this._RequestURL = RequestURL;
this._ResponseURL = ResponseURL;
this._FileName = FileName;
this._AttachmentName = AttachmentName;
this._Position = Position;
this._Length = Length;
}

private ThreadCallbackHandler _ThreadCallback;

//
internal void StartDownloadFileChunk()
{
if (this._ThreadCallback != null)
{
this._ThreadCallback(this._RequestURL, this._FileName, this._Position, this._Length);
}
}

}

//委托代理线程的所执行的方法签名一致
public delegate void ThreadCallbackHandler(string S, string s, int I, int i);

//异常处理动作
public enum ExceptionActions
{
Throw,
CancelAll,
Ignore,
Retry
}

/// <summary>
/// 包含 Exception 事件数据的类
/// </summary>
public class ExceptionEventArgs : System.EventArgs
{
private System.Exception _Exception;
private ExceptionActions _ExceptionAction;

private DownLoadState _DownloadState;

public DownLoadState DownloadState
{
get
{
retu