java - 一个简单的java客户端服务器程序

Question

所以我为我的大学迷你项目用 Java 编写了这个客户端服务器程序。请注意，这只是我正在进行的一个大项目的一个小模块。我需要一个字符串从客户端发送到服务器。服务器将返回给客户端的字符串。 (稍后将修改代码，以便在发送回之前处理字符串)。客户端将在需要时向服务器发送一个字符串。因此，这意味着服务器必须无限期运行。

我在这里面临的问题是，我的服务器仅在客户端第一次发送字符串时才能完美运行。如果我第二次使用不同的字符串运行客户端，我将返回之前发送到服务器的相同字符串!

这是我的服务器程序:

        public class Server {

        public static boolean x = true;
        public static String reply;

        public static void main(String a[]) throws Exception {

        System.out.println("Entered server console..");
            Socket echoSocket = null;
            ServerSocket serverSocket = null;
            PrintWriter out = null;
            BufferedReader in = null;

            System.out.println("Initializing Connection..");

            boolean runFlag = true;
            try {
                serverSocket = new ServerSocket(77);

                while (runFlag) {
                    echoSocket = serverSocket.accept();

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

                    BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));

                    while (x) {

                        in = new BufferedReader(new InputStreamReader(echoSocket.getInputStream()));
                        reply = in.readLine();
                        if (reply != null) {
                            x = false;
                        }
                    }
                    System.out.println("received: " + reply);

                    out.println(reply);

                    System.out.println("sent back: " + reply);
                    stdIn.close();
                }

            } catch (Exception e) {
                System.out.println("Exception in starting server: " + e.getMessage());
            } finally {
                out.close();
                in.close();
                echoSocket.close();
            }

        }
    }

这是我的客户端程序:

    public class Client {
    public static String reply,temp;
    public static boolean x=true;

    public Client()
    {
        temp="lala";
    }
    public Client(String t)
    {
        temp=t;
    }

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

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

        try {
            echoSocket = new Socket("localhost", 77);
            out = new PrintWriter(echoSocket.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(echoSocket.getInputStream()));
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host: localhost.");
            System.exit(1);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: localhost.");
            System.exit(1);
        }

        BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));

        temp="lala"; //this is the string to be sent

        out.println(temp);

        while (x) {
            reply= in.readLine();
            if(reply!=null)
            {
                x=false;
            }
        }

        System.out.println("reply: "+reply);

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

谁能帮我找出问题所在？

Answer 1

while (x) {
   in = new BufferedReader(new InputStreamReader(echoSocket.getInputStream()));
   reply = in.readLine();
   if (reply != null) {
      x = false;
   }
}

您的服务器在客户端第一次连接时进入此循环，并将回复字符串设置为来自客户端的一些输入。但是，它再也不会进入此循环，因为 x 的值永远不会变回 true。