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Net/C#: 实现支持断点续传多线程下载2

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[align=center].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)[/align]

/* .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
{
return _DownloadState;
}
}

public Exception Exception
{
get
{
return _Exception;
}
}

public ExceptionActions ExceptionAction
{
get
{
return _ExceptionAction;
}
set
{
_ExceptionAction = value;
}
}

internal ExceptionEventArgs(System.Exception e, DownLoadState DownloadState)
{
this._Exception = e;
this._DownloadState = DownloadState;
}
}

/// <summary>
/// 包含 DownLoad 事件数据的类
/// </summary>
public class DownLoadEventArgs : System.EventArgs
{
private DownLoadState _DownloadState;

public DownLoadState DownloadState
{
get
{
return _DownloadState;
}
}

public DownLoadEventArgs(DownLoadState DownloadState)
{
this._DownloadState = DownloadState;
}

}

/// <summary>
/// 支持断点续传多线程下载的类
/// </summary>
public class HttpWebClient
{
private static object _SyncLockObject = new object();

public delegate void DataReceiveEventHandler(HttpWebClient Sender, DownLoadEventArgs e);

public event DataReceiveEventHandler DataReceive; //接收字节数据事件

public delegate void ExceptionEventHandler(HttpWebClient Sender, ExceptionEventArgs e);

public event ExceptionEventHandler ExceptionOccurrs; //发生异常事件

private int _FileLength; //下载文件的总大小

public int FileLength
{
get
{
return _FileLength;
}
}

/// <summary>
/// 分块下载文件
/// </summary>
/// <param name="Address">URL 地址</param>
/// <param name="FileName">保存到本地的路径文件名</param>
/// <param name="ChunksCount">块数,线程数</param>
public void DownloadFile(string Address, string FileName, int ChunksCount)
{
int p = 0; // position
int s = 0; // chunk size
string a = null;
HttpWebRequest hwrq;
HttpWebResponse hwrp = null;
try
{
hwrq = (HttpWebRequest) WebRequest.Create(this.GetUri(Address));
hwrp = (HttpWebResponse) hwrq.GetResponse();
long L = hwrp.ContentLength;

hwrq.Credentials = this.m_credentials;

L = ((L == -1) || (L > 0x7fffffff)) ? ((long) 0x7fffffff) : L; //Int32.MaxValue 该常数的值为 2,147,483,647; 即十六进制的 0x7FFFFFFF

int l = (int) L;

this._FileLength = l;

// 在本地预定空间(竟然在多线程下不用先预定空间)
// FileStream sw = new FileStream(FileName, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
// sw.Write(new byte[l], 0, l);
// sw.Close();
// sw = null;

bool b = (hwrp.Headers["Accept-Ranges"] != null & hwrp.Headers["Accept-Ranges"] == "bytes");
a = hwrp.Headers["Content-Disp

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