在 C# winform 中断开连接后无法进行服务器重新连接
Unable to do server reconnection after disconnected in C# winform
我正在做一个应用程序,它要求我作为客户端连接到服务器并从服务器接收数据。当连接断开时,我将需要重新连接。下面是我的代码:
public enum MySocketState
{
Disconnected = 0,
Connecting,
Connected
}
private Socket _serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
private byte[] _recieveBuffer = new byte[128];
void DataProcess()
{
try
{
if (_serverSocket == null || sockState == MySocketState.Disconnected)
{
Console.WriteLine("Trying to connect...");
SetupServer();
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
private void SetupServer()
{
try
{
_serverSocket.Connect("192.168.1.11", 1000);
}
catch (SocketException ex)
{
Console.WriteLine(ex.Message);
}
sockState = MySocketState.Connected;
Console.WriteLine("Server connected...");
_serverSocket.BeginReceive(_recieveBuffer, 0, _recieveBuffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), null);
}
private void ReceiveCallback(IAsyncResult AR)
{
try
{
if (_serverSocket == null)
_serverSocket = (Socket)AR.AsyncState;
int recieved = _serverSocket.EndReceive(AR);
if (recieved <= 0)
{
CloseSocket();
return;
}
byte[] recData = new byte[recieved];
Buffer.BlockCopy(_recieveBuffer, 0, recData, 0, recieved);
string strData = ASCIIEncoding.ASCII.GetString(recData);
Console.WriteLine(strData);
//Process the data stored in recData
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
CloseSocket();
}
finally
{
try
{
//Start receiving again
if (_serverSocket != null)
_serverSocket.BeginReceive(_recieveBuffer, 0, _recieveBuffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), null);
}
catch (Exception ex2)
{ }
}
}
public void CloseSocket()
{
try
{
if (_serverSocket != null)
{
if (_serverSocket.Connected)
_serverSocket.Shutdown(SocketShutdown.Both);
_serverSocket.Close();
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
_serverSocket = null;
sockState = MySocketState.Disconnected;
}
private void timer1_Tick(object sender, EventArgs e)
{
DataProcess();
}
我正在使用计时器 (timer1_tick) 始终检测服务器是否已连接。
但是与服务器断开连接后,无法重新连接,下面是第_serverSocket.Connect("192.168.1.11", 1000)
行的错误信息:
A first chance exception of type 'System.NullReferenceException' occurred in fform.exe
System.NullReferenceException: Object reference not set to an instance of an object.
at fform.Form1.SetupServer() in c:\Work\Project 2015\Form1.cs:line 143
at fform.Form1.DataProcess() in c:\Work\Project 2015\Form1.cs:line 79
你们知道怎么连不上吗?
可能是因为您在 CloseSocket() 之后将 _serverSocket 设置为 null,并且在尝试重新连接时没有创建新的 Socket 实例。
public void CloseSocket()
{
...
_serverSocket = null;
...
}
查看报错信息中的行号
at fform.Form1.SetupServer() in c:\Work\Project 2015\Form1.cs:line
143 at fform.Form1.DataProcess() in c:\Work\Project
2015\Form1.cs:line 79
重新连接时,您可能应该执行以下操作:
private void SetupServer()
{
try
{
_serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); //Added
_serverSocket.Connect("192.168.1.11", 1000);
}
...
}
我正在做一个应用程序,它要求我作为客户端连接到服务器并从服务器接收数据。当连接断开时,我将需要重新连接。下面是我的代码:
public enum MySocketState
{
Disconnected = 0,
Connecting,
Connected
}
private Socket _serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
private byte[] _recieveBuffer = new byte[128];
void DataProcess()
{
try
{
if (_serverSocket == null || sockState == MySocketState.Disconnected)
{
Console.WriteLine("Trying to connect...");
SetupServer();
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
private void SetupServer()
{
try
{
_serverSocket.Connect("192.168.1.11", 1000);
}
catch (SocketException ex)
{
Console.WriteLine(ex.Message);
}
sockState = MySocketState.Connected;
Console.WriteLine("Server connected...");
_serverSocket.BeginReceive(_recieveBuffer, 0, _recieveBuffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), null);
}
private void ReceiveCallback(IAsyncResult AR)
{
try
{
if (_serverSocket == null)
_serverSocket = (Socket)AR.AsyncState;
int recieved = _serverSocket.EndReceive(AR);
if (recieved <= 0)
{
CloseSocket();
return;
}
byte[] recData = new byte[recieved];
Buffer.BlockCopy(_recieveBuffer, 0, recData, 0, recieved);
string strData = ASCIIEncoding.ASCII.GetString(recData);
Console.WriteLine(strData);
//Process the data stored in recData
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
CloseSocket();
}
finally
{
try
{
//Start receiving again
if (_serverSocket != null)
_serverSocket.BeginReceive(_recieveBuffer, 0, _recieveBuffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), null);
}
catch (Exception ex2)
{ }
}
}
public void CloseSocket()
{
try
{
if (_serverSocket != null)
{
if (_serverSocket.Connected)
_serverSocket.Shutdown(SocketShutdown.Both);
_serverSocket.Close();
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
_serverSocket = null;
sockState = MySocketState.Disconnected;
}
private void timer1_Tick(object sender, EventArgs e)
{
DataProcess();
}
我正在使用计时器 (timer1_tick) 始终检测服务器是否已连接。
但是与服务器断开连接后,无法重新连接,下面是第_serverSocket.Connect("192.168.1.11", 1000)
行的错误信息:
A first chance exception of type 'System.NullReferenceException' occurred in fform.exe
System.NullReferenceException: Object reference not set to an instance of an object.
at fform.Form1.SetupServer() in c:\Work\Project 2015\Form1.cs:line 143
at fform.Form1.DataProcess() in c:\Work\Project 2015\Form1.cs:line 79
你们知道怎么连不上吗?
可能是因为您在 CloseSocket() 之后将 _serverSocket 设置为 null,并且在尝试重新连接时没有创建新的 Socket 实例。
public void CloseSocket()
{
...
_serverSocket = null;
...
}
查看报错信息中的行号
at fform.Form1.SetupServer() in c:\Work\Project 2015\Form1.cs:line 143 at fform.Form1.DataProcess() in c:\Work\Project 2015\Form1.cs:line 79
重新连接时,您可能应该执行以下操作:
private void SetupServer()
{
try
{
_serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); //Added
_serverSocket.Connect("192.168.1.11", 1000);
}
...
}