Question

我想创建一个简单的服务器客户端应用程序，但我认为IO Streams存在问题。没有GUI，所以聊天将通过控制台进行（你可以打开2 eclipse来测试它或你正在使用的任何IDE）。

这是我的服务器代码：

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class Server {
    ServerSocket serverSocket;
    Socket connection; // connection-to-client
    ObjectOutputStream output;
    ObjectInputStream input;

    public void run() {
        try {
            serverSocket = new ServerSocket(6000, 100);
        } catch (IOException e) {
            System.err.println("Invalid port number");
        }
        while (true) {
            try {
                waitForConnection();
                getIOStreams();
                processConnection();
            } finally {
                closeConnection();
            }
        }
    }

    public void closeConnection() {
        try {
            input.close();
            output.close();
            connection.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void waitForConnection() {
        System.out.println("Server is ready to accept conenctions");
        try {
            connection = serverSocket.accept(); // code will stop here until a
                                                // connection occurs
            System.out.println("Conenction established with the client");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void getIOStreams() {
        try {
            output = new ObjectOutputStream(connection.getOutputStream());
            output.flush(); // send header information to the client, which
                            // contains info required to create the input stream
                            // object
            input = new ObjectInputStream(connection.getInputStream());
            System.out.println("Server established I/O streams");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void processConnection() {
        sendData("Connection established with the server");
        String inputMessage = "";
        new Runnable() {
            Scanner sc = new Scanner(System.in);

            public void run() {
                while (true) {
                    sendData(sc.nextLine());
                }
            }
        };
        do {

            try {
                inputMessage = (String) input.readObject();
                System.out.println(inputMessage);
            } catch (ClassNotFoundException e) {
                System.err.println("Object of an unknown type was recieved");
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        } while (inputMessage.equals("QUIT"));
    }

    public void sendData(String s) {
        try {
            output.writeObject(s);
            output.flush();
            System.out.println("Server: " + s);
        } catch (IOException e) {
            System.err.println("Error writting the message");
        }
    }
}

这是我的客户代码

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;

public class Client {
    ServerSocket serverSocket;
    Socket clientSocket;
    ObjectOutputStream output;
    ObjectInputStream input;
    String serverAddress = "127.0.0.1";

    public void run() {
        connect2Server();
        getIOStreams();
        processConnection();
        closeConnection();
    }

    public void connect2Server() {
        System.out.println("Trying to connect to the server");
        try {
            clientSocket = new Socket(serverAddress, 6000);
        } catch (UnknownHostException e) {
            System.err.println("Server unavailable");
            System.exit(1);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public void getIOStreams() {
        try {
            output = new ObjectOutputStream(clientSocket.getOutputStream());
            output.flush();
            input = new ObjectInputStream(clientSocket.getInputStream());
            System.out.println("Client established I/O Stream");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void processConnection() {
        sendData("Connection established with the client");
        String inputMessage = "";
        new Runnable() {
            Scanner sc = new Scanner(System.in);

            public void run() {
                String outputMessage = "";
                do {
                    outputMessage = sc.nextLine();
                    sendData("Client: " + outputMessage);
                } while (outputMessage.equals("QUIT"));
            }
        };
        while (true) {

            try {
                inputMessage = (String) input.readObject();
                System.out.println(inputMessage);
            } catch (ClassNotFoundException e) {
                System.err.println("Object of an unknown type was recieved");
            } catch (IOException e) {
                e.printStackTrace();
                System.exit(1);
            }
        }
    }

    public void sendData(String s) {
        try {
            output.writeObject(s);
            output.flush();
            System.out.println("Client: " + s);
        } catch (IOException e) {
            System.err.println("Error writting the message");
        }
    }

    public void closeConnection() {
        try {
            output.close();
            input.close();
            clientSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

运行服务器或客户端只需在main client / server.run（）中写入; 请告诉我我的错误是什么以及如何解决它：）

Answer 1

有几点：

1）输入循环结束的条件不正确：

while (inputMessage.equals("QUIT")); // Server#processConnection 

while (outputMessage.equals("QUIT")) // Client#processConnection

这些应该被否定（“！”）。

2）你应该开始System.in阅读帖子：

new Thread() { // instead of `Runnable`
   ...
}.start();

3）你应该在服务器上断开监听循环以寻找一些例外，例如EOFException，这意味着客户端已断开连接。

Java简单的服务器/客户端控制台聊天应用

1 个答案: