socket 异步接收的问题

[clickchen2003]

//以下的程序是msdn上的关于socket异步接收的例子(socket --异步客户端套接字)， 我在调试的过程中 怎么发现ReceiveCallback里面的一个if语句从来都没有执行过（他下面的那句执行了）,不知所以， 哪位高手可以帮我解释一下


public class StateObject
{
public Socket workSocket = null; // Client socket.
public const int BufferSize = 76; // Size of receive buffer.
public byte[] buffer = new byte[BufferSize]; // Receive buffer.
public StringBuilder sb = new StringBuilder();// Received data string.
}

public 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)
{
MessageBox.Show(e.ToString());
}
}

private static void ReceiveCallback( IAsyncResult ar )
{
try
{
// Retrieve the state object and the client socket
// from the async 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.Default.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.
//这个if语句似乎从来都没有执行
if(state.sb.Length > 1)
{
response = state.sb.ToString();
MessageBox.Show(response);
}
// Signal that all bytes have been received.
receiveDone.Set();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

[ptxq]

if语句主要判断有没有节收到数据，然后进行处理。如果没有数据收到，自然不会执行了。

[clickchen2003]

是if(state.sb.Length > 1)这个判断都没有执行？

[xixigongzhu]

你在三个分支的前面各自加个打印语句，把条件打印出来，先测试一下程序运行的路径。