Socket通信入门小实例

客户端：

public class Client {

    private int port = 8000;
    private String host = "localhost";
    private Socket socket;  

    public Client() throws UnknownHostException, IOException {
        socket = new Socket(host, port);
    }  

    public void readFromUser() throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line;
        while((line = br.readLine()) != null){
            if(line.equals("bye")){
                socket.close();
                System.out.println("关闭socket");
                break;
            }
            send(line);
        }
    }  

    public void send(String msg) throws IOException {
        PrintWriter pw = new PrintWriter(socket.getOutputStream(), true);
        pw.println(msg);
    }  

    public static void main(String args[]) throws UnknownHostException,
            IOException {
        new Client().readFromUser();
    }
}

服务端：

public class Server {

    private int port = 8000;
    private ServerSocket serverSocket;
    private ExecutorService executorService;
    private final int POOL_SIZE = 4;  

    public Server() throws IOException {
        serverSocket = new ServerSocket(port, 2);
        // 创建线程池
        executorService = Executors.newFixedThreadPool(Runtime.getRuntime()
                .availableProcessors()
                * POOL_SIZE);
        System.out.println("服务器启动。。。。。" + "初始线程数："
                + Runtime.getRuntime().availableProcessors() * POOL_SIZE);
    }  

    public void service() throws IOException {
        int count = 0;
        while (true) {
            Socket socket = serverSocket.accept();
            System.out.println(++count + "客户端已链接");
            // new Thread(new Handler(socket)).start();
            executorService.execute(new Handler(socket));
        }
    }  

    public static void main(String args[]) throws IOException {
        new Server().service();
    }  

    private class Handler implements Runnable {  

        private Socket socket;  

        public Handler(Socket socket) {
            this.socket = socket;
        }  

        public void run() {
            try {
                handle();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }  

        private void handle() throws IOException {
            BufferedReader br = new BufferedReader(new InputStreamReader(socket
                    .getInputStream()));
            String line;
            while ((line = br.readLine()) != null) {
                if(line.equals("goodbye")){
                    socket.close();
                    serverSocket.close();
                    break;
                }
                System.out.println("From " + socket.getPort() + ":" + line);
            }
        }
    }
}

服务器采用了JDK自带的线程池来处理并发请求。

还可以使用NIO来实现，即非阻塞通信