C#通讯编程（多方面收集并整理）

C# code

public class XmlSocket
{

//异步socket诊听
// Incoming data from client.从客户端传来的数据
public static string data = null;

// Thread signal.线程 用一个指示是否将初始状态设置为终止的布尔值初始化 ManualResetEvent 类的新实例。
public static ManualResetEvent allDone = new ManualResetEvent(false);
//static void Main(string[] args)
//{
// StartListening();
//}

public static void StartListening()
{
// Data buffer for incoming data. 传入数据缓冲
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket. 建立本地端口
// The DNS name of the computer
// running the listener is "host.contoso.com".

IPAddress ipAddress;
String ipString = ConfigurationManager.AppSettings.Get("SocketIP");
if (ipString==null || ipString ==String.Empty)
{
IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
ipAddress = ipHostInfo.AddressList[0];
}
else
{
ipAddress = IPAddress.Parse(ipString);
}

int port;
String portString = ConfigurationManager.AppSettings.Get("SocketPort");
if (portString==null || portString==String.Empty)
{
port = 11001;
}
else
{
port = int.Parse(portString);
}
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, port);

// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);

// Bind the socket to the local endpoint and listen for incoming connections.绑定端口和数据
try
{
listener.Bind(localEndPoint);
listener.Listen(100);

while (true)
{
// Set the event to nonsignaled state.设置无信号状态的事件
allDone.Reset();
// Start an asynchronous socket to listen for connectio
4000
ns.重新 启动异步连接
listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
// Wait until a connection is made before continuing.等待连接创建后继续
allDone.WaitOne();
}
}
catch (Exception e)
{
//
}
}

public static void AcceptCallback(IAsyncResult ar)
{
try
{
// Signal the main thread to continue.接受回调方法 该方法的此节向主应用程序线程发出信号，
//让它继续处理并建立与客户端的连接
allDone.Set();
// Get the socket that handles the client request.获取客户端请求句柄
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
catch (Exception e)
{
//
}
}

/// <summary>
/// 与接受回调方法一样，读取回调方法也是一个 AsyncCallback 委托。
/// 该方法将来自客户端套接字的一个或多个字节读入数据缓冲区，然后再次调用 BeginReceive 方法，直到客户端发送的数据完成为止。
/// 从客户端读取整个消息后，在控制台上显示字符串，并关闭处理与客户端的连接的服务器套接字。
/// </summary>
/// <param name="ar">IAsyncResult 委托</param>
public static void ReadCallback(IAsyncResult ar)
{
try
{
String content = String.Empty;
// Retrieve the state object and the handler socket创建自定义的状态对象 from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.workSocket;//处理的句柄
// Read data from the client socket. 读出
int bytesRead = handler.EndReceive(ar);
if (bytesRead > 0)
{
//业务代码
string result = DoSomeThing(...);
String len = Encoding.UTF8.GetBytes(result).Length.ToString().PadLeft(8, '0');
log.writeLine(len);
Send(len + result, handler);
}
}
catch (Exception e)
{
//
}

}
private static void Send(String data, Socket handler)
{
try
{
// Convert the string data to byte data using UTF8 encoding.
byte[] byteData = Encoding.UTF8.GetBytes(data);
// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}
catch (Exception e)
{
//
}
}
/// <summary>
/// 发送
/// </summary>
/// <param name="ar"></param>
private static void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket handler = (Socket)ar.AsyncState;

// Complete sending the data to the remote device.向远端发送数据
int bytesSent = handler.EndSend(ar);
StateObject state = new StateObject();
state.workSocket = handler;

handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,new AsyncCallback(ReadCallback), state);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
catch (Exception e)
{
　　　　　　　　　　　　　　//
}
}

public static void StopListening()
{
allDone.Close();
log.close();
}

/// <summary>
/// 具体处理业务的方法
/// </summary>
/// <returns></returns>
private static string DoSomething(int i)
{
//具体业务代码,返回需要返回的字符串信息
}
/// <summary>
/// 写日志方法
/// </summary>
/// <param name="strLog">写入内容</param>
public static void WriteLog(string strLog)
{
//写入日志代码
}
}

 

/// 线程执行体,转发消息
/// </summary>
/// <param name="obj">传递给线程执行体的用户名，用以与用户通信 </param>
private void ThreadFunc(object obj)
{
//通过转发表得到当前用户套接字
Socket clientSkt = _transmit_tb[obj] as Socket;
//主循环
while (true)
{
try
{ //接受第一个数据包。
//由于程序逻辑结构简单，所以在这里对客户机发送的第一个包内容作逐一判断，
//这里的实现不够优雅，但不失为此简单模型的一个解决之道。
byte[] packetBuff = new byte[_maxPacket];
clientSkt.Receive(packetBuff);
string _str = Encoding.Unicode.GetString(packetBuff).TrimEnd('/0');
//如果是发给不在线好友的信息
if (_str.StartsWith("cmd::FriendMessage"))
{
string UserName = _str.Substring("cmd::FriendMessage".Length, 20).Trim();
string MessageS = _str.Substring("cmd::FriendMessage".Length + 20, _str.Length - "cmd::FriendMessage".Length - 20);
SaveMessage(obj as string, UserName, MessageS);
continue;
}
//如果是离线请求
if (_str.StartsWith("cmd::RequestLogout"))
{
_transmit_tb.Remove(obj);
UpdateFriendList((string)obj, false, "");
// string svrlog = string.Format("[系统消息]用户 {0} 在 {1} 已断开... 当前在线人数: {2}/r/n/r/n", obj, DateTime.Now, _transmit_tb.Count);
// Console.WriteLine(svrlog);
//向所有客户机发送系统消息

//foreach (DictionaryEntry de in _transmit_tb)
//{
// string _clientName = de.Key as string;
// Socket _clientSkt = de.Value as Socket;
// _clientSkt.Send(Encoding.Unicode.GetBytes(svrlog));
//}
Thread.CurrentThread.Abort();
}
//如果是请求好友列表
if (_str.StartsWith("cmd::RequestFriendList"))
{
SerializeFriendList(obj, clientSkt);
// 将该用户不在线时的信息发送给用户
DataTable TabMessage = ReadMessage(obj as string);
if (TabMessage != null)
{
foreach (DataRow myrow in TabMessage.Rows)
{
if (myrow["SendUserName"].ToString() == "System::Message")
{
clientSkt.Send(Encoding.Unicode.GetBytes(myrow["Message"].ToString()));
}
else
{
clientSkt.Send(Encoding.Unicode.GetBytes("cmd::FriendMessage" + myrow["SendUserName"].ToString().PadRight(20, ' ') + myrow["Message"].ToString()));
}
}
} //这里不需要再继续接受后继数据包了，跳出当前循环体。
continue;
}
////如果是请求好友列表
//if (_str.StartsWith("cmd::RequestOnLineList"))
//{
// byte[] onlineBuff = SerializeOnlineList();
// //先发送响应信号，用户客户机的判断
// clientSkt.Send(Encoding.Unicode.GetBytes("cmd::RequestOnLineList"));
// clientSkt.Send(onlineBuff);
// //这里不需要再继续接受后继数据包了，跳出当前循环体。
// continue;
//} //查找用户
if (_str.StartsWith("Find::FindFriend"))
{
DataTable TabFind = TabUser.Clone();
DataRow [] FindRow =null ;
string UserName = _str.Substring("Find::FindFriend".Length, _str.Length - "Find::FindFriend".Length);
if (UserName.Equals("Find::WhoOnLine"))
{ //看谁在线
FindRow = TabUser.Select(" ZX = 1");
}
else//精确查找
{
FindRow = TabUser.Select("UserName = '" + UserName + "'");
}
foreach (DataRow myrow in FindRow)
{
TabFind.ImportRow(myrow);
}

clientSkt.Send(Encoding.Unicode.GetBytes("Find::FindFriend"));
IFormatter format = new BinaryFormatter();
MemoryStream stream = new MemoryStream();
format.Serialize(stream, TabFind);
stream.Position = 0;
byte[] ret = new byte[_maxPacket];
int count = 0;
count = stream.Read(ret, 0, _maxPacket);
while (count >0)
{
clientSkt.Send(ret);
count = stream.Read(ret, 0, _maxPacket);
}
clientSkt.Send(Encoding.Unicode.GetBytes("Find::FindFriendEnd"));
stream.Close();
TabFind = null;
FindRow = null; //这里不需要再继续接受后继数据包了，跳出当前循环体。
continue;
} //请求添加好友
if (_str.StartsWith("Find::AddFriendAsk"))
{
string UserName = _str.Substring("Find::AddFriendAsk".Length, _str.Length - "Find::AddFriendAsk".Length);
//通过转发表查找接收方的套接字
if (_transmit_tb.Count != 0 && _transmit_tb.ContainsKey(UserName))
{
Socket receiverSkt = _transmit_tb[UserName] as Socket;
receiverSkt.Send(Encoding.Unicode.GetBytes("Find::AddFriendAsk" + obj as string));
}
//这里不需要再继续接受后继数据包了，跳出当前循环体。
continue;
}
//回复答应添加好友
if (_str.StartsWith("Find::AddFriendYes"))
{
string UserName = _str.Substring("Find::AddFriendYes".Length, _str.Length - "Find::AddFriendYes".Length);
//// 保存数据
DataTable TabmyFriend = new DataTable() ;
//保存该用户
TabmyFriend.ReadXml(MyPath + "//UserFriend//" + obj as string + ".xml");
DataRow newRow = TabmyFriend.NewRow();
newRow["UserName"] = UserName;
TabmyFriend.Rows.Add(newRow);
TabmyFriend.WriteXml(MyPath + "//UserFriend//" + obj as string + ".xml", XmlWriteMode.WriteSchema, false);
//保存其好友
TabmyFriend = new DataTable();
TabmyFriend.ReadXml(MyPath + "//UserFriend//" + UserName + ".xml");
DataRow newRow1 = TabmyFriend.NewRow();
newRow1["UserName"] = obj as string;
TabmyFriend.Rows.Add(newRow1);
TabmyFriend.WriteXml(MyPath + "//UserFriend//" + UserName + ".xml", XmlWriteMode.WriteSchema, false);
TabmyFriend = null;
SerializeFriendList(obj, clientSkt);
//"开始"按钮事件

private void button1_Click(object sender, System.EventArgs e) {

//取得预保存的文件名

string fileName=textBox3.Text.Trim();

//远程主机

string hostName=textBox1.Text.Trim();

//端口

int port=Int32.Parse(textBox2.Text.Trim());

//得到主机信息

IPHostEntry ipInfo=Dns.GetHostByName(hostName);

//取得IPAddress[]

IPAddress[] ipAddr=ipInfo.AddressList;

//得到ip

IPAddress ip=ipAddr[0];

//组合出远程终结点

IPEndPoint hostEP=new IPEndPoint(ip,port);

//创建Socket 实例

Socket socket=new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);

try

{

//尝试连接

socket.Connect(hostEP);

}

catch(Exception se)

{

MessageBox.Show("连接错误"+se.Message,"提示信息

,MessageBoxButtons.RetryCancel,MessageBoxIcon.Information);

}

//发送给远程主机的请求内容串

string sendStr="GET / HTTP/1.1/r/nHost: " + hostName +

"/r/nConnection: Close/r/n/r/n";

//创建bytes字节数组以转换发送串

byte[] bytesSendStr=new byte[1024];

//将发送内容字符串转换成字节byte数组

bytesSendStr=Encoding.ASCII.GetBytes(sendStr);

try

{

//向主机发送请求

socket.Send(bytesSendStr,bytesSendStr.Length,0);

}

catch(Exception ce)

{

MessageBox.Show("发送错误:"+ce.Message,"提示信息

,MessageBoxButtons.RetryCancel,MessageBoxIcon.Information);

}

//声明接收返回内容的字符串

string recvStr="";

//声明字节数组，一次接收数据的长度为1024字节

byte[] recvBytes=new byte[1024];

//返回实际接收内容的字节数

int bytes=0;

//循环读取，直到接收完所有数据

while(true)

{

bytes=socket.Receive(recvBytes,recvBytes.Length,0);

//读取完成后退出循环

if(bytes〈=0)

break;

//将读取的字节数转换为字符串

recvStr+=Encoding.ASCII.GetString(recvBytes,0,bytes);

}

//将所读取的字符串转换为字节数组

byte[] content=Encoding.ASCII.GetBytes(recvStr);

try

{

//创建文件流对象实例

FileStream fs=new FileStream(fileName,FileMode.OpenOrCreate,FileAccess.ReadWrite);

//写入文件

fs.Write(content,0,content.Length);

}

catch(Exception fe)

{

MessageBox.Show("文件创建/写入错误:"+fe.Message,"提示信息",MessageBoxButtons.RetryCancel,MessageBoxIcon.Information);

}

//禁用Socket

socket.Shutdown(SocketShutdown.Both);

//关闭Socket

socket.Close();

}

}

TCP/UDP通讯

namespace UDPServer
{
class Program
{
static void Main(string[] args)
{
int recv;
byte[] data = new byte[1024];

//构建TCP 服务器

//得到本机IP，设置TCP端口号
IPEndPoint ipep = new IPEndPoint(IPAddress.Any , 8001);
Socket newsock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram , ProtocolType.Udp);

//绑定网络地址
newsock.Bind(ipep);

Console.WriteLine("This is a Server, host name is {0}",Dns.GetHostName());

//等待客户机连接
Console.WriteLine("Waiting for a client...");

//得到客户机IP
IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
EndPoint Remote = (EndPoint)(sender);
recv = newsock.ReceiveFrom(data, ref Remote);
Console .WriteLine ("Message received from {0}: ", Remote.ToString ());
Console .WriteLine (Encoding .ASCII .GetString (data ,0,recv ));

//客户机连接成功后，发送欢迎信息
string welcome = "Welcome ! ";

//字符串与字节数组相互转换
data  = Encoding .ASCII .GetBytes (welcome );

//发送信息
newsock .SendTo (data ,data.Length ,SocketFlags .None ,Remote );
while (true )
{
data =new byte [1024];
//发送接受信息
recv =newsock.ReceiveFrom(data ,ref Remote);
Console .WriteLine (Encoding .ASCII .GetString (data ,0,recv));
newsock .SendTo (data ,recv ,SocketFlags .None ,Remote );
}
}

}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace UDPClient
{
class Program
{
static void Main(string[] args)
{
byte[] data = new byte[1024];
string input ,stringData;

//构建TCP 服务器

Console.WriteLine("This is a Client, host name is {0}", Dns.GetHostName());

//设置服务IP，设置TCP端口号
IPEndPoint ipep = new IPEndPoint(IPAddress .Parse ("127.0.0.1") , 8001);

//定义网络类型，数据连接类型和网络协议UDP
Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

string welcome = "Hello! ";
data = Encoding.ASCII.GetBytes(welcome);
server.SendTo(data, data.Length, SocketFlags.None, ipep);
IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
EndPoint Remote = (EndPoint)sender;

data = new byte[1024];
int recv = server.ReceiveFrom(data, ref Remote);
Console.WriteLine("Message received from {0}: ", Remote.ToString());
Console.WriteLine(Encoding .ASCII .GetString (data,0,recv));
while (true)
{
input = Console .ReadLine ();
if (input =="exit")
break ;
server .SendTo (Encoding .ASCII .GetBytes (input ),Remote );
data = new byte [1024];
recv = server.ReceiveFrom(data, ref Remote);
stringData = Encoding.ASCII.GetString(data, 0, recv);
Console.WriteLine(stringData);
}
Console .WriteLine ("Stopping Client.");
server .Close ();
}

}
}
简单的UDP

try
{
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);  //向此网段发广播包
int UDPListenerPort = 8082;
IPAddress broadcast = IPAddress.Parse("192.168.0.255"); //此处根据IP及子网掩码改为相应的广播IP
string ts = "This is UPD string for sending";
byte[] sendbuf = Encoding.ASCII.GetBytes(ts);
IPEndPoint ep = new IPEndPoint(broadcast, UDPListenerPort);
s.SendTo(sendbuf, ep);
}
catch (Exception e)
{}

          UdpClient listener;
int UDPListenerPort = 8082;
IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, UDPListenerPort);

try
{
while (true)
{
byte[] bytes = listener.Receive(ref groupEP);
string RecIP = groupEP.ToString().Substring(0, groupEP.ToString().IndexOf(":"));  //收到发送UPD端的IP
string RecStr = Encoding.ASCII.GetString(bytes, 0, bytes.Length);   //收到的UPD字符串
}
}
catch
{}

C# code

//"开始"按钮事件

  private void button1_Click(object sender, System.EventArgs e) {

  //取得预保存的文件名

  string fileName=textBox3.Text.Trim();

  //远程主机

  string hostName=textBox1.Text.Trim();

  //端口

  int port=Int32.Parse(textBox2.Text.Trim());

  //得到主机信息

  IPHostEntry ipInfo=Dns.GetHostByName(hostName);

  //取得IPAddress[]

C#UDP的多路广播组的发送和接收
下列范例使用 UdpClient，在通讯端口11000传送UDP 资料包至多点传送位址群组 224.268.100.2。它传送命令列上指定的信息字串。

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

public class UDPMulticastSender {

private static IPAddress GroupAddress =
IPAddress.Parse("224.168.100.2");
private static int GroupPort = 11000;

private static void Send( String message) {
UdpClient sender = new UdpClient();
IPEndPoint groupEP = new IPEndPoint(GroupAddress,GroupPort);

try {
Console.WriteLine("Sending datagram : {0}", message);
byte[] bytes = Encoding.ASCII.GetBytes(message);

sender.Send(bytes, bytes.Length, groupEP);

sender.Close();

} catch (Exception e) {
Console.WriteLine(e.ToString());
}

}

public static int Main(String[] args) {
Send(args[0]);

return 0;
}
}

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

public class UDPMulticastListener {

private static readonly IPAddress GroupAddress =
IPAddress.Parse("224.168.100.2");
private const int GroupPort = 11000;

private static void StartListener() {
bool done = false;

UdpClient listener = new UdpClient();
IPEndPoint groupEP = new IPEndPoint(GroupAddress,GroupPort);

try {
listener.JoinMulticastGroup(GroupAddress);
listener.Connect(groupEP);

while (!done) {
Console.WriteLine("Waiting for broadcast");
byte[] bytes = listener.Receive( ref groupEP);

Console.WriteLine("Received broadcast from {0} :/n {1}/n",
groupEP.ToString(),
Encoding.ASCII.GetString(bytes,0,bytes.Length));
}

listener.Close();

} catch (Exception e) {
Console.WriteLine(e.ToString());
}

}

public static int Main(String[] args) {
StartListener();

return 0;
}
}

C# code

TCPClient
TCPClient 类提供了一种使用 TCP 协议连接到某个端点的简化方法。它还通过 NetworkStream 对象展现在连接过程中读取或写入的数据。请参见下面从 QuickStart 文档中摘录的日期/时间客户机示例。

使用 C# 编写
using System;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Text;
class Client
{
public static void Main(String[] args)
{
TCPClient tcpc = new TCPClient();
Byte[] read = new Byte[32];
if (args.Length != 1)
{
Console.WriteLine(“请在命令行中指定服务器名称”);
return;
}
String server = args[0];
// 验证服务器是否存在
if (DNS.GetHostByName(server) == null)
{
Console.WriteLine(“找不到服务器：” + 服务器);
return;
}
// 尝试连接到服务器
if (tcpc.Connect(server, 13) == -1)
{
Console.WriteLine(“无法连接到服务器：” + 服务器);
return;
}
// 获取流
Stream s = tcpc.GetStream();
// 读取流并将它转换为 ASCII 码形式
int bytes = s.Read(read, 0, read.Length);
String Time = Encoding.ASCII.GetString(read);
// 显示数据
Console.WriteLine(“已接收到的” + 字节 + “字节”);
Console.WriteLine(“当前日期和时间是：” + 时间);
tcpc.Close();
}
}

TCPListener
TCPListener 类便于在来自某个客户机的 TCP 连接的特定套接字上进行侦听的工作。请参见下面包括在 QuickStart 文档中的日期/时间服务器示例。

使用 C# 编写
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
class Server
{
public static void Main()
{
DateTime now;
String strDateLine;
Encoding ASCII = Encoding.ASCII;
// 在端口 13 进行侦听
TCPListener tcpl = new TCPListener(13);
tcpl.Start();
Console.WriteLine(“正在等待客户进行连接”);
Console.WriteLine(“请按 Ctrl+c 退出...”);
while (true)
{
// 接收会阻塞，直到有人连接上
Socket s = tcpl.Accept();
// 获取当前的日期和时间并将它连接成一个字符串
now = DateTime.Now;
strDateLine = now.ToShortDateString() + " " +
now.ToLongTimeString();
// 将该字符串转换成一个字节数组并发送它
Byte[] byteDateLine =
ASCII.GetBytes(strDateLine.ToCharArray());
s.Send(byteDateLine, byteDateLine.Length, 0);
Console.WriteLine(“发送” + strDateLine);
}
}
}

这个似乎是FTP下载的：

C# code

#region "Download: File transfer FROM ftp server"
/// <summary>
/// Copy a file from FTP server to local
/// </summary>
/// <param name="sourceFilename">Target filename, if required </param>
/// <param name="localFilename">Full path of the local file </param>
/// <returns> </returns>
/// <remarks>Target can be blank (use same filename), or just a filename
/// (assumes current directory) or a full path and filename </remarks>
public bool Download(string sourceFilename, string localFilename, bool PermitOverwrite)
{
//2. determine target file
FileInfo fi = new FileInfo(localFilename);
return this.Download(sourceFilename, fi, PermitOverwrite);
}

//Version taking an FtpFileInfo
public bool Download(FtpFileInfo file, string localFilename, bool permitOverwrite)
{
return this.Download(file.FullName, localFilename, permitOverwrite);
}

//Another version taking FtpFileInfo and FileInfo
public bool Download(FtpFileInfo file, FileInfo localFI, bool permitOverwrite)
{
return this.Download(file.FullName, localFI, permitOverwrite);
}

//Version taking string/FileInfo
public bool Download(string sourceFilename, FileInfo targetFI, bool permitOverwrite)
{
//1. check target
if (targetFI.Exists && !(permitOverwrite))
{
throw (new ApplicationException("Target file already exists"));
}

//2. check source
string target;
if (sourceFilename.Trim() == "")
{
throw (new ApplicationException("File not specified"));
}
else if (sourceFilename.Contains("/"))
{
//treat as a full path
target = AdjustDir(sourceFilename);
}
else
{
//treat as filename only, use current directory
target = CurrentDirectory + sourceFilename;
}

string URI = Hostname + target;

//3. perform copy
System.Net.FtpWebRequest ftp = GetRequest(URI);

//Set request to download a file in binary mode
ftp.Method = System.Net.WebRequestMethods.Ftp.DownloadFile;
ftp.UseBinary = true;

//open request and get response stream
using (FtpWebResponse response = (FtpWebResponse)ftp.GetResponse())
{
using (Stream responseStream = response.GetResponseStream())
{
//loop to read & write to file
using (FileStream fs = targetFI.OpenWrite())
{
try
{
byte[] buffer = new byte[2048];
int read = 0;
do
{
read = responseStream.Read(buffer, 0, buffer.Length);
fs.Write(buffer, 0, read);
} while (!(read == 0));
responseStream.Close();
fs.Flush();
fs.Close();
}
catch (Exception)
{
//catch error and delete file only partially downloaded
fs.Close();
//delete target file as it's incomplete
targetFI.Delete();
throw;
}
}

responseStream.Close();
}

response.Close();
}

return true;
}
#endregion

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