这篇文章将为大家详细讲解有关C#如何实现支持断点续传多线程下载客户端工具类，小编觉得挺实用的，因此分享给大家做个参考，希望大家阅读完这篇文章后可以有所收获。
代码如下:
/* .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 ,改写或增加了若干: * 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 */ //2005-03-14 修订: /* .Net/C#: 实现支持断点续传多线程下载的工具类 * Reflector 了一下 System.Net.WebClient ,改写或增加了若干: * DownLoad、Upload 相关方法! * 增加了 DataReceive、ExceptionOccurrs 事件 */ 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; public HttpWebClient httpWebClient { get { return this._hwc; } set { this._hwc = value; } } internal Thread thread { get { return _thread; } set { _thread = value; } } private HttpWebClient _hwc; private Thread _thread; // internal void StartDownloadFileChunk() { if (this._ThreadCallback != null) { this._ThreadCallback(this._RequestURL, this._FileName, this._Position, this._Length); this._hwc.OnThreadProcess(this._thread); } } } //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; } } public class ThreadProcessEventArgs : System.EventArgs { private Thread _thread; public Thread thread { get { return this._thread; } } public ThreadProcessEventArgs(Thread thread) { this._thread = thread; } } /// <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 public delegate void ThreadProcessEventHandler(HttpWebClient Sender, ThreadProcessEventArgs e); public event ThreadProcessEventHandler ThreadProcessEnd; //发生多线程处理完毕事件 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-Disposition"]; //attachment if (a != null) { a = a.Substring(a.LastIndexOf("filename=") + 9); } else { a = FileName; } int ss = s; if (b) { s = l / ChunksCount; if (s < 2 * 64 * 1024) //块大小至少为 128 K 字节 { s = 2 * 64 * 1024; } ss = s; int i = 0; while (l > s) { l -= s; if (l < s) { s += l; } if (i++ > 0) { DownLoadState x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, p, s, new ThreadCallbackHandler(this.DownloadFileChunk)); // 单线程下载 // x.StartDownloadFileChunk(); x.httpWebClient = this; //多线程下载 Thread t = new Thread(new ThreadStart(x.StartDownloadFileChunk)); //this.OnThreadProcess(t); t.Start(); } p += s; } s = ss; byte[] buffer = this.ResponseAsBytes(Address, hwrp, s, FileName); this.OnThreadProcess(Thread.CurrentThread); // lock (_SyncLockObject) // { // this._Bytes += buffer.Length; // } } } catch (Exception e) { ExceptionActions ea = ExceptionActions.Throw; if (this.ExceptionOccurrs != null) { DownLoadState x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, p, s); ExceptionEventArgs eea = new ExceptionEventArgs(e, x); ExceptionOccurrs(this, eea); ea = eea.ExceptionAction; } if (ea == ExceptionActions.Throw) { if (!(e is WebException) && !(e is SecurityException)) { throw new WebException("net_webclient", e); } throw; } } } internal void OnThreadProcess(Thread t) { if (ThreadProcessEnd != null) { ThreadProcessEventArgs tpea = new ThreadProcessEventArgs(t); ThreadProcessEnd(this, tpea); } } /// <summary> /// 下载一个文件块,利用该方法可自行实现多线程断点续传 /// </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="Length">块大小</param> public void DownloadFileChunk(string Address, string FileName, int FromPosition, int Length) { HttpWebResponse hwrp = null; string a = null; try { //this._FileName = FileName; HttpWebRequest hwrq = (HttpWebRequest) WebRequest.Create(this.GetUri(Address)); //hwrq.Credentials = this.m_credentials; hwrq.AddRange(FromPosition); hwrp = (HttpWebResponse) hwrq.GetResponse(); a = hwrp.Headers["Content-Disposition"]; //attachment if (a != null) { a = a.Substring(a.LastIndexOf("filename=") + 9); } else { a = FileName; } byte[] buffer = this.ResponseAsBytes(Address, hwrp, Length, FileName); // lock (_SyncLockObject) // { // this._Bytes += buffer.Length; // } } catch (Exception e) { ExceptionActions ea = ExceptionActions.Throw; if (this.ExceptionOccurrs != null) { DownLoadState x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, FromPosition, Length); ExceptionEventArgs eea = new ExceptionEventArgs(e, x); ExceptionOccurrs(this, eea); ea = eea.ExceptionAction; } if (ea == ExceptionActions.Throw) { if (!(e is WebException) && !(e is SecurityException)) { throw new WebException("net_webclient", e); } throw; } } } internal byte[] ResponseAsBytes(string RequestURL, WebResponse Response, long Length, string FileName) { string a = null; //AttachmentName int P = 0; //整个文件的位置指针 int num2 = 0; try { a = Response.Headers["Content-Disposition"]; //attachment if (a != null) { a = a.Substring(a.LastIndexOf("filename=") + 9); } long num1 = Length; //Response.ContentLength; bool flag1 = false; if (num1 == -1) { flag1 = true; num1 = 0x10000; //64k } byte[] buffer1 = new byte[(int) num1]; int p = 0; //本块的位置指针 string s = Response.Headers["Content-Range"]; if (s != null) { s = s.Replace("bytes ", ""); s = s.Substring(0, s.IndexOf("-")); P = Convert.ToInt32(s); } int num3 = 0; Stream S = Response.GetResponseStream(); do { num2 = S.Read(buffer1, num3, ((int) num1) - num3); num3 += num2; if (flag1 && (num3 == num1)) { num1 += 0x10000; byte[] buffer2 = new byte[(int) num1]; Buffer.BlockCopy(buffer1, 0, buffer2, 0, num3); buffer1 = buffer2; } // lock (_SyncLockObject) // { // this._bytes += num2; // } if (num2 > 0) { if (this.DataReceive != null) { byte[] buffer = new byte[num2]; Buffer.BlockCopy(buffer1, p, buffer, 0, buffer.Length); DownLoadState dls = new DownLoadState(RequestURL, Response.ResponseUri.AbsolutePath, FileName, a, P, num2, buffer); DownLoadEventArgs dlea = new DownLoadEventArgs(dls); //触发事件 this.OnDataReceive(dlea); //System.Threading.Thread.Sleep(100); } p += num2; //本块的位置指针 P += num2; //整个文件的位置指针 } else { break; } } while (num2 != 0); S.Close(); S = null; if (flag1) { byte[] buffer3 = new byte[num3]; Buffer.BlockCopy(buffer1, 0, buffer3, 0, num3); buffer1 = buffer3; } return buffer1; } catch (Exception e) { ExceptionActions ea = ExceptionActions.Throw; if (this.ExceptionOccurrs != null) { DownLoadState x = new DownLoadState(RequestURL, Response.ResponseUri.AbsolutePath, FileName, a, P, num2); ExceptionEventArgs eea = new ExceptionEventArgs(e, x); ExceptionOccurrs(this, eea); ea = eea.ExceptionAction; } if (ea == ExceptionActions.Throw) { if (!(e is WebException) && !(e is SecurityException)) { throw new WebException("net_webclient", e); } throw; } return null; } } private void OnDataReceive(DownLoadEventArgs e) { //触发数据到达事件 DataReceive(this, e); } public byte[] UploadFile(string address, string fileName) { return this.UploadFile(address, "POST", fileName, "file"); } public string UploadFileEx(string address, string method, string fileName, string fieldName) { return Encoding.ASCII.GetString(UploadFile(address, method, fileName, fieldName)); } public byte[] UploadFile(string address, string method, string fileName, string fieldName) { byte[] buffer4; FileStream stream1 = null; try { fileName = Path.GetFullPath(fileName); string text1 = "---------------------" + DateTime.Now.Ticks.ToString("x"); string text2 = "application/octet-stream"; stream1 = new FileStream(fileName, FileMode.Open, FileAccess.Read); WebRequest request1 = WebRequest.Create(this.GetUri(address)); request1.Credentials = this.m_credentials; request1.ContentType = "multipart/form-data; boundary=" + text1; request1.Method = method; string[] textArray1 = new string[7] {"--", text1, "\r\nContent-Disposition: form-data; name=\"" + fieldName + "\"; filename=\"", Path.GetFileName(fileName), "\"\r\nContent-Type: ", text2, "\r\n\r\n"}; string text3 = string.Concat(textArray1); byte[] buffer1 = Encoding.UTF8.GetBytes(text3); byte[] buffer2 = Encoding.ASCII.GetBytes("\r\n--" + text1 + "\r\n"); long num1 = 0x7fffffffffffffff; try { num1 = stream1.Length; request1.ContentLength = (num1 + buffer1.Length) + buffer2.Length; } catch { } byte[] buffer3 = new byte[Math.Min(0x2000, (int) num1)]; using (Stream stream2 = request1.GetRequestStream()) { int num2; stream2.Write(buffer1, 0, buffer1.Length); do { num2 = stream1.Read(buffer3, 0, buffer3.Length); if (num2 != 0) { stream2.Write(buffer3, 0, num2); } } while (num2 != 0); stream2.Write(buffer2, 0, buffer2.Length); } stream1.Close(); stream1 = null; WebResponse response1 = request1.GetResponse(); buffer4 = this.ResponseAsBytes(response1); } catch (Exception exception1) { if (stream1 != null) { stream1.Close(); stream1 = null; } if (!(exception1 is WebException) && !(exception1 is SecurityException)) { //throw new WebException(SR.GetString("net_webclient"), exception1); throw new WebException("net_webclient", exception1); } throw; } return buffer4; } private byte[] ResponseAsBytes(WebResponse response) { int num2; long num1 = response.ContentLength; bool flag1 = false; if (num1 == -1) { flag1 = true; num1 = 0x10000; } byte[] buffer1 = new byte[(int) num1]; Stream stream1 = response.GetResponseStream(); int num3 = 0; do { num2 = stream1.Read(buffer1, num3, ((int) num1) - num3); num3 += num2; if (flag1 && (num3 == num1)) { num1 += 0x10000; byte[] buffer2 = new byte[(int) num1]; Buffer.BlockCopy(buffer1, 0, buffer2, 0, num3); buffer1 = buffer2; } } while (num2 != 0); stream1.Close(); if (flag1) { byte[] buffer3 = new byte[num3]; Buffer.BlockCopy(buffer1, 0, buffer3, 0, num3); buffer1 = buffer3; } return buffer1; } private NameValueCollection m_requestParameters; private Uri m_baseAddress; private ICredentials m_credentials = CredentialCache.DefaultCredentials; public ICredentials Credentials { get { return this.m_credentials; } set { this.m_credentials = value; } } public NameValueCollection QueryString { get { if (this.m_requestParameters == null) { this.m_requestParameters = new NameValueCollection(); } return this.m_requestParameters; } set { this.m_requestParameters = value; } } public string BaseAddress { get { if (this.m_baseAddress != null) { return this.m_baseAddress.ToString(); } return string.Empty; } set { if ((value == null) || (value.Length == 0)) { this.m_baseAddress = null; } else { try { this.m_baseAddress = new Uri(value); } catch (Exception exception1) { throw new ArgumentException("value", exception1); } } } } private Uri GetUri(string path) { Uri uri1; try { if (this.m_baseAddress != null) { uri1 = new Uri(this.m_baseAddress, path); } else { uri1 = new Uri(path); } if (this.m_requestParameters == null) { return uri1; } StringBuilder builder1 = new StringBuilder(); string text1 = string.Empty; for (int num1 = 0; num1 < this.m_requestParameters.Count; num1++) { builder1.Append(text1 + this.m_requestParameters.AllKeys[num1] + "=" + this.m_requestParameters[num1]); text1 = "&"; } UriBuilder builder2 = new UriBuilder(uri1); builder2.Query = builder1.ToString(); uri1 = builder2.Uri; } catch (UriFormatException) { uri1 = new Uri(Path.GetFullPath(path)); } return uri1; } } } /// <summary> /// 测试类 /// </summary> class AppTest { int _k = 0; int _K = 0; static void Main() { AppTest a = new AppTest(); Microshaoft.Utils.HttpWebClient x = new Microshaoft.Utils.HttpWebClient(); a._K = 10; //订阅 DataReceive 事件 x.DataReceive += new Microshaoft.Utils.HttpWebClient.DataReceiveEventHandler(a.x_DataReceive); //订阅 ExceptionOccurrs 事件 x.ExceptionOccurrs += new Microshaoft.Utils.HttpWebClient.ExceptionEventHandler(a.x_ExceptionOccurrs); x.ThreadProcessEnd += new Microshaoft.Utils.HttpWebClient.ThreadProcessEventHandler(a.x_ThreadProcessEnd); string F = "http://localhost/download/phpMyAdmin-2.6.1-pl2.zip"; F = "http://down6.flashget.com/flashget182cn.exe"; a._F = F; string f = F.Substring(F.LastIndexOf("/") + 1); //(new System.Threading.Thread(new System.Threading.ThreadStart(new ThreadProcessState(F, @"E:\temp\" + f, 10, x).StartThreadProcess))).Start(); x.DownloadFile(F, @"d:\temp\" + f, a._K); // x.DownloadFileChunk(F, @"E:\temp\" + f,15,34556); System.Console.ReadLine(); // string uploadfile = "e:\\test_local.rar"; // string str = x.UploadFileEx("http://localhost/phpmyadmin/uploadaction.php", "POST", uploadfile, "file1"); // System.Console.WriteLine(str); // System.Console.ReadLine(); } string bs = ""; //用于记录上次的位数 bool b = false; private int i = 0; private static object _SyncLockObject = new object(); string _F; string _f; private void x_DataReceive(Microshaoft.Utils.HttpWebClient Sender, Microshaoft.Utils.DownLoadEventArgs e) { if (!this.b) { lock (_SyncLockObject) { if (!this.b) { System.Console.Write(System.DateTime.Now.ToString() + " 已接收数据: "); //System.Console.Write( System.DateTime.Now.ToString() + " 已接收数据: "); this.b = true; } } } string f = e.DownloadState.FileName; if (e.DownloadState.AttachmentName != null) f = System.IO.Path.GetDirectoryName(f) + @"\" + e.DownloadState.AttachmentName; this._f = f; using (System.IO.FileStream sw = new System.IO.FileStream(f, System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.ReadWrite, System.IO.FileShare.ReadWrite)) { sw.Position = e.DownloadState.Position; sw.Write(e.DownloadState.Data, 0, e.DownloadState.Data.Length); sw.Close(); } string s = System.DateTime.Now.ToString(); lock (_SyncLockObject) { this.i += e.DownloadState.Data.Length; System.Console.Write(bs + "\b\b\b\b\b\b\b\b\b\b"+ i + " / " + Sender.FileLength + " 字节数据 " + s); //System.Console.Write(bs + i + " 字节数据 " + s); this.bs = new string('\b', Digits(i) + 3 + Digits(Sender.FileLength) + s.Length); } } int Digits(int n) //数字所占位数 { n = System.Math.Abs(n); n = n / 10; int i = 1; while (n > 0) { n = n / 10; i++; } return i; } private void x_ExceptionOccurrs(Microshaoft.Utils.HttpWebClient Sender, Microshaoft.Utils.ExceptionEventArgs e) { System.Console.WriteLine(e.Exception.Message); //发生异常重新下载相当于断点续传,你可以自己自行选择处理方式 Microshaoft.Utils.HttpWebClient x = new Microshaoft.Utils.HttpWebClient(); x.DownloadFileChunk(this._F, this._f, e.DownloadState.Position, e.DownloadState.Length); e.ExceptionAction = Microshaoft.Utils.ExceptionActions.Ignore; } private void x_ThreadProcessEnd(Microshaoft.Utils.HttpWebClient Sender, Microshaoft.Utils.ThreadProcessEventArgs e) { //if (e.thread.ThreadState == System.Threading.ThreadState.Stopped) if (this._k ++ == this._K - 1) System.Console.WriteLine("\nend"); } }
C#是一个简单、通用、面向对象的编程语言，它由微软Microsoft开发，继承了C和C++强大功能，并且去掉了一些它们的复杂特性，C#综合了VB简单的可视化操作和C++的高运行效率，以其强大的操作能力、优雅的语法风格、创新的语言特性和便捷的面向组件编程从而成为.NET开发的首选语言，但它不适用于编写时间急迫或性能非常高的代码，因为C#缺乏性能极高的应用程序所需要的关键功能。
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