C# 为什么调用BeginConnect时我的表单会冻结？

我使用的这个例子来自

使用系统；
Net系统；
使用System.Net.Sockets；
使用系统线程；
使用系统文本；
//用于从远程设备接收数据的状态对象。
公共类StateObject{
//客户端套接字。
公共套接字工作组=null；
//接收缓冲区的大小。
public const int BufferSize=256；
//接收缓冲区。
公共字节[]缓冲区=新字节[BufferSize]；
//接收到的数据字符串。
公共StringBuilder sb=新StringBuilder（）；
}  
公共类异步客户端{
//远程设备的端口号。
专用常量int端口=11000；
//ManualResetEvent实例信号完成。
专用静态手动重置事件连接完成=
新手动重置事件（错误）；
专用静态手动重置事件sendDone=
新手动重置事件（错误）；
私有静态手动重置事件receiveDone=
新手动重置事件（错误）；
//来自远程设备的响应。
私有静态字符串响应=String.Empty；
私有静态void StartClient（）{
//连接到远程设备。
试试{
//为套接字建立远程端点。
//名称
//远程设备是“host.contoso.com”。
IPHostEntry ipHostInfo=Dns.GetHostEntry（“host.contoso.com”）；
IPAddress IPAddress=ipHostInfo.AddressList[0]；
IPEndPoint remoteEP=新IPEndPoint（ipAddress，端口）；
//创建TCP/IP套接字。
套接字客户端=新套接字（ipAddress.AddressFamily，
流，ProtocolType.Tcp）；
//连接到远程端点。
client.BeginConnect（remoteEP，
新的异步回调（ConnectCallback），客户端）；
connectDone.WaitOne（）；
//将测试数据发送到远程设备。
发送（客户端，“这是一个测试”）；
sendDone.WaitOne（）；
//从远程设备接收响应。
接收（客户）；
receiveDone.WaitOne（）；
//将响应写入控制台。
WriteLine（“收到的响应：{0}”，响应）；
//松开插座。
client.Shutdown（SocketShutdown.Both）；
client.Close（）；
}捕获（例外e）{
Console.WriteLine（如ToString（））；
}  
}  
私有静态无效连接回调（IAsyncResult ar）{
试试{
//从状态对象检索套接字。
套接字客户端=（套接字）ar.AsyncState；
//完成连接。
客户端.EndConnect（ar）；
WriteLine（“连接到{0}的套接字”，
client.RemoteEndPoint.ToString（））；
//表示已建立连接的信号。
connectDone.Set（）；
}捕获（例外e）{
Console.WriteLine（如ToString（））；
}  
}  
私有静态void接收（套接字客户端）{
试试{
//创建状态对象。
StateObject状态=新的StateObject（）；
state.workSocket=客户端；
//开始从远程设备接收数据。
client.BeginReceive（state.buffer，0，StateObject.BufferSize，0，
新建异步回调（ReceiveCallback），状态）；
}捕获（例外e）{
Console.WriteLine（如ToString（））；
}  
}  
私有静态void ReceiveCallback（IAsyncResult ar）{
试试{
//检索状态对象和客户端套接字
//从异步状态对象。
StateObject状态=（StateObject）ar.AsyncState；
套接字客户端=state.workSocket；
//从远程设备读取数据。
int bytesRead=client.EndReceive（ar）；
如果（字节读取>0）{
//可能会有更多数据，因此请存储到目前为止收到的数据。
state.sb.Append（Encoding.ASCII.GetString（state.buffer，0，bytesRead））；
//获取其余的数据。
client.BeginReceive（state.buffer，0，StateObject.BufferSize，0，
新建异步回调（ReceiveCallback），状态）；
}否则{
//所有数据都已到达，请将其作为响应。
如果（状态sb.Length>1）{
response=state.sb.ToString（）；
}  
//表示已接收到所有字节的信号。
receiveDone.Set（）；
}  
}捕获（例外e）{
Console.WriteLine（如ToString（））；
}  
}  
私有静态void发送（套接字客户端，字符串数据）{
//使用ASCII编码将字符串数据转换为字节数据。
byte[]byteData=Encoding.ASCII.GetBytes（数据）；
//开始将数据发送到远程设备。
client.BeginSend（byteData，0，byteData.Length，0，
新的异步回调（SendCallback），客户端）；
}  
私有静态void SendCallback（IAsyncResult ar）{
试试{
//从状态对象检索套接字。
套接字客户端=（套接字）ar.AsyncState；
//完成将数据发送到远程设备。
int bytesent=client.EndSend（ar）；
WriteLine（“向服务器发送了{0}个字节。”，bytesSent）；
//表示已发送所有字节的信号。
sendDone.Set（）；
}捕获（例外e）{
Console.WriteLine（如ToString（））；
}  
}  
公共静态int Main（字符串[]args）{
StartClient（）；
返回0；
}  
}  

我正在为我的应用程序r的网络端编程

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

// State object for receiving data from remote device.  
public class StateObject {  
    // Client socket.  
    public Socket workSocket = null;  
    // Size of receive buffer.  
    public const int BufferSize = 256;  
    // Receive buffer.  
    public byte[] buffer = new byte[BufferSize];  
    // Received data string.  
    public StringBuilder sb = new StringBuilder();  
}  

public class AsynchronousClient {  
    // The port number for the remote device.  
    private const int port = 11000;  

    // ManualResetEvent instances signal completion.  
    private static ManualResetEvent connectDone =   
        new ManualResetEvent(false);  
    private static ManualResetEvent sendDone =   
        new ManualResetEvent(false);  
    private static ManualResetEvent receiveDone =   
        new ManualResetEvent(false);  

    // The response from the remote device.  
    private static String response = String.Empty;  

    private static void StartClient() {  
        // Connect to a remote device.  
        try {  
            // Establish the remote endpoint for the socket.  
            // The name of the   
            // remote device is "host.contoso.com".  
            IPHostEntry ipHostInfo = Dns.GetHostEntry("host.contoso.com");  
            IPAddress ipAddress = ipHostInfo.AddressList[0];  
            IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);  

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

            // Connect to the remote endpoint.  
            client.BeginConnect( remoteEP,   
                new AsyncCallback(ConnectCallback), client);  
            connectDone.WaitOne();  

            // Send test data to the remote device.  
            Send(client,"This is a test<EOF>");  
            sendDone.WaitOne();  

            // Receive the response from the remote device.  
            Receive(client);  
            receiveDone.WaitOne();  

            // Write the response to the console.  
            Console.WriteLine("Response received : {0}", response);  

            // Release the socket.  
            client.Shutdown(SocketShutdown.Both);  
            client.Close();  

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

    private static void ConnectCallback(IAsyncResult ar) {  
        try {  
            // Retrieve the socket from the state object.  
            Socket client = (Socket) ar.AsyncState;  

            // Complete the connection.  
            client.EndConnect(ar);  

            Console.WriteLine("Socket connected to {0}",  
                client.RemoteEndPoint.ToString());  

            // Signal that the connection has been made.  
            connectDone.Set();  
        } catch (Exception e) {  
            Console.WriteLine(e.ToString());  
        }  
    }  

    private static void Receive(Socket client) {  
        try {  
            // Create the state object.  
            StateObject state = new StateObject();  
            state.workSocket = client;  

            // Begin receiving the data from the remote device.  
            client.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0,  
                new AsyncCallback(ReceiveCallback), state);  
        } catch (Exception e) {  
            Console.WriteLine(e.ToString());  
        }  
    }  

    private static void ReceiveCallback( IAsyncResult ar ) {  
        try {  
            // Retrieve the state object and the client socket   
            // from the asynchronous state object.  
            StateObject state = (StateObject) ar.AsyncState;  
            Socket client = state.workSocket;  

            // Read data from the remote device.  
            int bytesRead = client.EndReceive(ar);  

            if (bytesRead > 0) {  
                // There might be more data, so store the data received so far.  
            state.sb.Append(Encoding.ASCII.GetString(state.buffer,0,bytesRead));  

                // Get the rest of the data.  
                client.BeginReceive(state.buffer,0,StateObject.BufferSize,0,  
                    new AsyncCallback(ReceiveCallback), state);  
            } else {  
                // All the data has arrived; put it in response.  
                if (state.sb.Length > 1) {  
                    response = state.sb.ToString();  
                }  
                // Signal that all bytes have been received.  
                receiveDone.Set();  
            }  
        } catch (Exception e) {  
            Console.WriteLine(e.ToString());  
        }  
    }  

    private static void Send(Socket client, String data) {  
        // Convert the string data to byte data using ASCII encoding.  
        byte[] byteData = Encoding.ASCII.GetBytes(data);  

        // Begin sending the data to the remote device.  
        client.BeginSend(byteData, 0, byteData.Length, 0,  
            new AsyncCallback(SendCallback), client);  
    }  

    private static void SendCallback(IAsyncResult ar) {  
        try {  
            // Retrieve the socket from the state object.  
            Socket client = (Socket) ar.AsyncState;  

            // Complete sending the data to the remote device.  
            int bytesSent = client.EndSend(ar);  
            Console.WriteLine("Sent {0} bytes to server.", bytesSent);  

            // Signal that all bytes have been sent.  
            sendDone.Set();  
        } catch (Exception e) {  
            Console.WriteLine(e.ToString());  
        }  
    }  

    public static int Main(String[] args) {  
        StartClient();  
        return 0;  
    }  
}  

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

// State object for receiving data from remote device.  
public class StateObject {  
    // Client socket.  
    public Socket workSocket = null;  
    // Size of receive buffer.  
    public const int BufferSize = 256;  
    // Receive buffer.  
    public byte[] buffer = new byte[BufferSize];  
    // Received data string.  
    public StringBuilder sb = new StringBuilder();  
}  

public class AsynchronousClient {  
    // The port number for the remote device.  
    private const int port = 11000;  

    // ManualResetEvent instances signal completion.  
    private static ManualResetEvent connectDone =   
        new ManualResetEvent(false);  
    private static ManualResetEvent sendDone =   
        new ManualResetEvent(false);  
    private static ManualResetEvent receiveDone =   
        new ManualResetEvent(false);  

    // The response from the remote device.  
    private static String response = String.Empty;  

    private static void StartClient() {  
        // Connect to a remote device.  
        try {  
            // Establish the remote endpoint for the socket.  
            // The name of the   
            // remote device is "host.contoso.com".  
            IPHostEntry ipHostInfo = Dns.GetHostEntry("host.contoso.com");  
            IPAddress ipAddress = ipHostInfo.AddressList[0];  
            IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);  

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

            // Connect to the remote endpoint.  
            client.BeginConnect( remoteEP,   
                new AsyncCallback(ConnectCallback), client);  


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

    private static void ConnectCallback(IAsyncResult ar) {  
        try {  
            // Retrieve the socket from the state object.  
            Socket client = (Socket) ar.AsyncState;  

            // Complete the connection.  
            client.EndConnect(ar);  

            Console.WriteLine("Socket connected to {0}",  
                client.RemoteEndPoint.ToString());  

            // we do it here now...
            Send(client,"This is a test<EOF>");  
        } catch (Exception e) {  
            Console.WriteLine(e.ToString());  
        }  
    }  

    private static void Receive(Socket client) {  
        try {  
            // Create the state object.  
            StateObject state = new StateObject();  
            state.workSocket = client;  

            // Begin receiving the data from the remote device.  
            client.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0,  
                new AsyncCallback(ReceiveCallback), state);  
        } catch (Exception e) {  
            Console.WriteLine(e.ToString());  
        }  
    }  

    private static void ReceiveCallback( IAsyncResult ar ) {  
        try {  
            // Retrieve the state object and the client socket   
            // from the asynchronous state object.  
            StateObject state = (StateObject) ar.AsyncState;  
            Socket client = state.workSocket;  

            // Read data from the remote device.  
            int bytesRead = client.EndReceive(ar);  

            if (bytesRead > 0) {  
                // There might be more data, so store the data received so far.  
            state.sb.Append(Encoding.ASCII.GetString(state.buffer,0,bytesRead));  

                // Get the rest of the data.  
                client.BeginReceive(state.buffer,0,StateObject.BufferSize,0,  
                    new AsyncCallback(ReceiveCallback), state);  
            } else {  
                // All the data has arrived; put it in response.  
                if (state.sb.Length > 1) {  
                    response = state.sb.ToString();  
                }  

                // after all is done, we shut down the socket
                client.Shutdown(SocketShutdown.Both);  
                client.Close();  
            }  
        } catch (Exception e) {  
            Console.WriteLine(e.ToString());  
        }  
    }  

    private static void Send(Socket client, String data) {  
        // Convert the string data to byte data using ASCII encoding.  
        byte[] byteData = Encoding.ASCII.GetBytes(data);  

        // Begin sending the data to the remote device.  
        client.BeginSend(byteData, 0, byteData.Length, 0,  
            new AsyncCallback(SendCallback), client);  
    }  

    private static void SendCallback(IAsyncResult ar) {  
        try {  
            // Retrieve the socket from the state object.  
            Socket client = (Socket) ar.AsyncState;  

            // Complete sending the data to the remote device.  
            int bytesSent = client.EndSend(ar);  
            Console.WriteLine("Sent {0} bytes to server.", bytesSent);  

            // We do it here now...
            Receive(client); 
        } catch (Exception e) {  
            Console.WriteLine(e.ToString());  
        }  
    }  

    public static int Main(String[] args) {  
        StartClient();  
        return 0;  
    }  
}