这个程序的思路是共同做一件事情（从一个ArrayList中删除元素）,如果执行完成了，两个线程都停止执行。

代码如下：

using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;

///
/// 在开发中经常会遇到线程的例子，如果某个后台操作比较费时间，我们就可以启动一个线程去执行那个费时的操作，同时程序继续执行。在某些情况下可能会出现多个线程的同步协同的问题，下面的例子就展示了在两个线程之间如何协同工作。
///
///这个程序的思路是共同做一件事情（从一个ArrayList中删除元素）,如果执行完成了，两个线程都停止执行。
///作者：周公
/// 时间：2008-5-17
/// 原发地址：http://blog.csdn.net/zhoufoxcn
///
public class ThreadDemo
{
private Thread threadOne;
private Thread threadTwo;
private ArrayList stringList;
private event EventHandler OnNumberClear;//数据删除完成引发的事件
public static void Main()
{
ThreadDemo demo = new ThreadDemo(1000);
demo.Action();
}
public ThreadDemo(int number)
{
Random random = new Random(1000000);
stringList = new ArrayList(number);
for (int i = 0; i < number; i++)
{
stringList.Add(random.Next().ToString());
}
threadOne = new Thread(new ThreadStart(Run));//两个线程共同做一件事情
threadTwo = new Thread(new ThreadStart(Run));//两个线程共同做一件事情
threadOne.Name = "线程1";
threadTwo.Name = "线程2";
OnNumberClear += new EventHandler(ThreadDemo_OnNumberClear);

}
///
/// 开始工作
///
public void Action()
{
threadOne.Start();
threadTwo.Start();
}
///
/// 共同做的工作
///
private void Run()
{
string stringValue = null;
while (true)
{
Monitor.Enter(this);//锁定，保持同步
stringValue = (string)stringList[0];
Console.WriteLine(Thread.CurrentThread.Name + "删除了" + stringValue);
stringList.RemoveAt(0);//删除ArrayList中的元素
if (stringList.Count == 0)
{
OnNumberClear(this, new EventArgs());//引发完成事件
}
Monitor.Exit(this);//取消锁定
Thread.Sleep(5);
}
}

//执行完成之后，停止所有线程
void ThreadDemo_OnNumberClear(object sender, EventArgs e)
{
Console.WriteLine("执行完了，停止了所有线程的执行。");
threadTwo.Abort();
threadOne.Abort();

}
}
说明：要实现线程同步不止这一种方式。在这里采用了事件，在事件处理程序里中止了线程（主要是回答csdn论坛的一个朋友的问题才用了这种办法）。

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;

///
/// 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
{
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
}

///
/// 包含 Exception 事件数据的类
///
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;
}
}

///
/// 包含 DownLoad 事件数据的类
///
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;
}

}

///
/// 支持断点续传多线程下载的类
///
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;
}
}

///
/// 分块下载文件
///
/// URL 地址
/// 保存到本地的路径文件名
/// 块数,线程数
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 s)
{
l -= s;
if (l 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);
}
}

///
/// 下载一个文件块,利用该方法可自行实现多线程断点续传
///
/// URL 地址
/// 保存到本地的路径文件名
/// 块大小
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;
}

}

}

///
/// 测试类
///
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";
a._F = F;
F = "http://localhost/download/jdk-1_5_0_01-windows-i586-p.aa.exe";

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, @"E:\temp\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");
}
}