socket编程---一个简单例子

import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class MultiEchoServer {
    private static ServerSocket serverSocket;
    private static final int PORT = 12345;

    public static void main(String[] args) throws IOException {
        try {
            serverSocket = new ServerSocket(PORT);
        } catch (IOException e) {
            System.out.println("Unable connect to the port");
            System.exit(1);
        }
        do {
            Socket client = serverSocket.accept();
            System.out.println("New client accept...");
            ClientHandler clientHandler = new ClientHandler(client);
            clientHandler.start();
        } while (true);
    }
}

class ClientHandler extends Thread {
    private Socket client;
    private Scanner input;
    private PrintWriter output;

    public ClientHandler(Socket client) {
        this.client = client;
        try {
            input = new Scanner(client.getInputStream());
            output = new PrintWriter(client.getOutputStream(),true);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        String receive = "";
        do {
            receive = input.nextLine();
            System.out.println("Server receive message:" + receive);
            output.println("Echo:" + receive);
        } while (!receive.equalsIgnoreCase("q"));
        try {
            if (client != null) {
                System.out.println("Closing connection...");
                client.close();
            }
        } catch (IOException e) {
            System.out.println("Unable to close connection...");
        }
    }
}

import java.io.IOException;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;

public class MultiEchoClient {
    private static InetAddress host;
    private static final int PORT = 12345;

    public static void main(String[] args) {
        try {
            host = InetAddress.getLocalHost();
        } catch (UnknownHostException e) {
            System.out.println("Host id not found!");
            System.exit(1);
        }
        SenderMessages();
    }

    public static void SenderMessages() {
        Socket socket = null;
        try {
            socket = new Socket(host, PORT);
            Scanner input = new Scanner(socket.getInputStream());
            PrintWriter outpout = new PrintWriter(socket.getOutputStream(),true);
            Scanner userInput = new Scanner(System.in);
            String message, response;
            do {
                System.out.println("Enter Message:");
                message = userInput.nextLine();
                outpout.println(message);
                response = input.nextLine();
                System.out.println("Server " + response);
            } while (!message.equalsIgnoreCase("q"));
            input.close();
            userInput.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (socket != null) {
                    System.out.println("Closing connetion...");
                    socket.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}