简单的客户端服务器通信

Question

I am learning currently about client server communication using Java through sockets. First of all I retrieve my own machine's IP Address using following code.

InetAddress ownIP=InetAddress.getLocalHost();
//the result being 192.168.56.1

Now I write the simple client server application using the above mentioned address as follow

public class SimpleClientServer {
public static void main(String[] args)
{
    //sending "Hello World" to the server
    Socket clientSocket = null;
    PrintWriter out = null;
    BufferedReader in = null;

    try
    {

        clientSocket = new Socket("192.168.56.1", 16000);

        out = new PrintWriter(clientSocket.getOutputStream(), true);

        in = new BufferedReader(new InputStreamReader(
                                                 clientSocket.getInputStream()));

        out.println("Hello World");

        out.close();
        in.close();
        clientSocket.close();
    }
    catch(IOException e)
    {
        System.err.println("Error occured " + e);

    }
}
}

The result hower reads a follow.

Error occured java.net.ConnectException: Connection refused: connect

What is the reason for this. Is it just the wrong host address?

Answer 1

From the code you have given you seem to suggest that there is currently nothing listening on port 16000 for the socket to connect to.

If this is the case you need to implement something like

ServerSocket serverSocket = null;
try {
    serverSocket = new ServerSocket(16000);
}
catch (IOException e) {
    System.err.println("Could not listen on port: 16000.");
    System.exit(1);
}

More information can be found in the Java online documentation and a full example is included.

Answer 2

With sockets, no matter what language you're using, you either initiate a connection with socket_connect or you listen and accept with socket_listen and socket_accept. Your socket_connect call is trying to connect to an ip address that doesn't seem to be listening to anything.