关于UDP连接的问题

Question

写了个客户端，连不上（服务器端没问题），主要代码如下byte[] incomingbuf = new byte[1<<16];
System.Diagnostics.Debug.WriteLine("connecting to port  " + _port);
try
{
    _socket = new System.Net.Sockets.UdpClient(60001);
    _socket.Connect("192.168.2.2", 10011);
    String str="connection request";
    byte[] buf = System.Text.Encoding.ASCII.GetBytes(str.ToCharArray());
    int count = _socket.Send(buf,buf.Length);
    System.Diagnostics.Debug.WriteLine(_port + ":  send a string with the count=" + count);
    System.Net.IPEndPoint ipendpoint = null;
    incommingbuf = _socket.Receive(ref ipendpoint);
    //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~在这收不到东西了
    System.Diagnostics.Debug.WriteLine(_port + ": connected");
    _isConnected = true;
}
catch
{
     System.Diagnostics.Debug.WriteLine(_port + ":catched an exception while connecting");
}
用java写了个同样的东西 却能收到东西，代码如下
byte[] incomingbuf = new byte[1<<16];
DatagramPacket incoming = new DatagramPacket(incomingbuf,incomingbuf.length);
try
{
_socket=new DatagramSocket();
_socket.connect(InetAddress.getByName(“192.168.2.2”), 10011);
String buf="connection request";
DatagramPacket message = new DatagramPacket(buf, buf.length);
_socket.send(message);
incomingbuf.length);_socket.setSoTimeout(500);
_socket.receive(incoming);
//~~~~~~~~~~~~~~~~~~~可以正常收到数据包
_socket.setSoTimeout(0); //set to be blocking
System.out.println("["+_port+"] connected ");
_isConnected=true;
} catch (Exception ex) {}哪位高手指点一下可能是什么原因吧，急！
谢谢 ：）

Answer 1

不好意思  java代码部分错了 更正如下
byte[] incomingbuf = new byte[1<<16];
DatagramPacket incoming = new DatagramPacket(incomingbuf,incomingbuf.length);
try
{
_socket=new DatagramSocket();
_socket.connect(InetAddress.getByName(“192.168.2.2”), 10011);byte[] buf = (new String("connection request")).getBytes();
DatagramPacket message = new DatagramPacket(buf, buf.length);
_socket.send(message);_socket.setSoTimeout(500);
_socket.receive(incoming);
//~~~~~~~~~~~~~~~~~~~可以正常收到数据包
_socket.setSoTimeout(0); //set to be blocking
System.out.println("["+_port+"] connected ");
_isConnected=true;
} catch (Exception ex) {}

Answer 2

1.udp协议无须连接
2.incommingbuf = _socket.Receive(ref ipendpoint); 参数 ipendpoint 为空//
IPEndPoint rep= new IPEndPoint(你的主机IP，端口号);
Byte[] receiveBytes = receivingUdpClient.Receive(ref rep);

Answer 3

System.Net.IPEndPoint ipendpoint = null;
    incommingbuf = _socket.Receive(ref ipendpoint);
 注意这两句
不就为null

Answer 4

System.Net.IPEndPoint ipendpoint = null;
    incommingbuf = _socket.Receive(ref ipendpoint);
 注意这两句
不应为null

Answer 5

呵呵，luyangph() 看得真切，引用对象不能为空