java - 客户端/服务器应用程序

Question

伙计们谁能告诉我我在这里做错了什么？下面是四个文件 Client, main, Server, main.尝试使用 fromServer.readLine() 后，客户端出现错误。
错误:客户端软件错误导致连接中止:接收失败

            package client;
            import java.io.*;
            import java.net.*;
            import java.util.Scanner;

            public class Client
            {
            private PrintWriter toServer;
            private BufferedReader fromServer;
            private Socket socket;
            public Client( )throws IOException
                {
                socket = new Socket("127.0.0.1",3000);
            }
            public void openStreams() throws IOException
                {

            //
            //        InputStream is = socket.getInputStream();
            //        OutputStream os = socket.getOutputStream();
            //        fromServer = new BufferedReader(new InputStreamReader(is));
            //        toServer = new PrintWriter(os, true);

                toServer = new PrintWriter(socket.getOutputStream(),true);
                fromServer = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            }
            public void closeStreams() throws IOException
                {
                fromServer.close();
                toServer.close();
                socket.close();
            }
            public void run()throws IOException
                {
                openStreams();
                String msg = "";
                Scanner scanner = new Scanner(System.in);
                toServer.println("Hello from Client.");
            //    msg = scanner.nextLine();
                while (msg != "exit")
                {
                    System.out.println(">");
            //        msg = scanner.nextLine();
                    toServer.println("msg");
                    String tmp = fromServer.readLine();
                    System.out.println("Server said: " + tmp);
                }
                closeStreams();
            }
            }



        package server;
        import java.net.*;
        import java.io.*;

        public class Server
        {
        private ServerSocket serverSocket;
        private Socket socket;
        private PrintWriter toClient;
        private BufferedReader fromClient;
        public void run() throws IOException
            {
            System.out.println("Server is waiting for connections...");
            while (true)
            {
                openStreams();
                processClient();
                closeStreams();
            }

        }
        public void openStreams() throws IOException
            {
            serverSocket = new ServerSocket(3000);
            socket = serverSocket.accept();
            toClient = new PrintWriter(socket.getOutputStream(),true);
            fromClient = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        }
        public void closeStreams() throws IOException
            {
            fromClient.close();
            toClient.close();
            socket.close();
            serverSocket.close();
        }
        public void processClient()throws IOException
            {
            System.out.println("Connection established.");
            String msg = fromClient.readLine();
            toClient.println("Client said " + msg);
        }
        }


    package client;

    import java.io.IOException;


    public class Main {

        /**
         * @param args the command line arguments
         */
        public static void main(String[] args) {
            // TODO code application logic here

            try
            {
                 Client client = new Client();
                 client.run();
            }
            catch(IOException e)
            {
                 System.err.println("Error in Client " + e.getMessage());
            }
        }

    }



package server;

import java.io.IOException;


public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        Server server = new Server();
        try
        {
        server.run();
        }
        catch(IOException e)
        {
            System.err.println("Error in Server " + e.getMessage());
        }
    }

}

Answer 1

你的服务器端都搞混了。您需要另一个实现 Runnable 的类，将其称为 Connection 或 ConnectedClient；将 Socket 作为构造函数参数；并为特定客户端执行所有服务器端 I/O。目前，您将这一切都与您的服务器类混在一起了。您的服务器类应该做的就是创建一个 ServerSocket，然后进入一个接受套接字并创建连接对象并为它们启动线程的循环。 Server 的 run() 方法中的 Socket 对象只是一个本地对象，关联的输入/输出流或读取器/写入器属于 Connection 类，而不是 Server 类。

这样您就可以同时处理多个客户，而不会互相干扰。

您的下一个问题是 readLine() 在另一端关闭连接时返回 null。每次调用 readLine() 时，您必须先测试它，然后再进行任何其他处理。

接下来，任何时候在使用 Socket 时遇到 SocketException 或 IOException 而不是 SocketTimeoutException 时，它就死了 - 关闭它，忘记客户端并退出线程(如果它发生在服务器中)。