简单的服务器/客户端套接字连接？

Question

我正在编写一个java套接字,其中服务器运行,客户端连接到服务器,服务器可以从客户端命令行读取.

首先,我想连接到服务器,这里是代码:

public class Server{
    public static void main(String[] args) throws IOException {

        ServerSocket serverSocket = null;

        try {
            serverSocket = new ServerSocket(10000);
        } catch (IOException e) {
            System.err.println("Could not listen on port: 4444.");
            e.printStackTrace();
            System.exit(1);
        }

        Socket clientSocket = null;
        try {
            clientSocket = serverSocket.accept();
        } catch (IOException e) {
            System.err.println("Accept failed.");
            System.exit(1);
        }

        PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
        BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        String inputLine, outputLine;

        out.close();
        in.close();
        clientSocket.close();
        serverSocket.close();
    }

}

这是我的客户:

public class Client {
    public static void main(String[] args) throws IOException {

        Socket socket = null;
        PrintWriter out = null;
        BufferedReader in = null;

        try {
            socket = new Socket("taranis", 4444);
            out = new PrintWriter(socket.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host: taranis.");
            System.exit(1);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: taranis.");
            System.exit(1);
        }

        BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
        String fromServer;
        String fromUser;

        while ((fromServer = in.readLine()) != null) {
            System.out.println("Server: " + fromServer);
            if (fromServer.equals("Bye."))
                break;

            fromUser = stdIn.readLine();
            if (fromUser != null) {
                System.out.println("Client: " + fromUser);
                out.println(fromUser);
            }
        }

        out.close();
        in.close();
        stdIn.close();
        socket.close();
    }
}

当我启动服务器时,我得到"无法收听端口:4444".

为什么？

更新:

现在我无法重新启动服务器,因为我得到了

java.net.BindException: Address already in use: JVM_Bind
    at java.net.DualStackPlainSocketImpl.bind0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketBind(Unknown Source)
    at java.net.AbstractPlainSocketImpl.bind(Unknown Source)
    at java.net.PlainSocketImpl.bind(Unknown Source)
    at java.net.ServerSocket.bind(Unknown Source)
    at java.net.ServerSocket.<init>(Unknown Source)
    at java.net.ServerSocket.<init>(Unknown Source)

我能做些什么呢？(我使用的是windows7)

Answer 1

在我看来,您的服务器没有侦听端口4444,而是侦听端口10000,但是您的客户端尝试连接到端口4444.

要在关闭应用程序时回答第二个问题,请确保实际终止它.有时,如果再次启动应用程序,则运行2次,并且很难看到其中一个应用程序仍处于打开状态.

希望我帮助其他请回复评论il check back you you late :)