java网络通信：同步阻塞式I/O模型(BIO)

缺点：一个线程只能处理一个客户端连接

服务端: 

public class TimeServer {
    public static void main(String[] args) throws IOException {
        int port = 8080;
        ServerSocket server = null;
        try {
            server = new ServerSocket(port);
            System.out.println("The time server is start in port : " + port);
            Socket socket = null;
            while (true) {
                socket = server.accept();//阻塞直到有新的连接
                //每监听到一个socket连接就生成一个新的线程来处理
                new Thread(new TimeServerHandler(socket)).start();
            }
        } finally {
            if (server != null) {
                System.out.println("The time server close");
                server.close();
                server = null;
            }
        }
    }
}

事务处理线程：

public class TimeServerHandler implements Runnable {
    private Socket socket;
    public TimeServerHandler(Socket socket) {
        this.socket = socket;
    }
    @Override
    public void run() {
        BufferedReader in = null;
        PrintWriter out = null;
        try {
            //获取输入输出流
            in = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            out = new PrintWriter(this.socket.getOutputStream(), true);

            String currentTime = null;
            String body = null;
            while (true) {
                body = in.readLine();//阻塞直到有数据读入，或者数据读完或发生异常
                if (body == null)
                    break;
                System.out.println("The time server receive order : " + body);
                currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new java.util.Date(
                        System.currentTimeMillis()).toString() : "BAD ORDER";
                out.println(currentTime);//输出
            }
        } catch (Exception e) {
            //处理异常
        }
    }
}

客户端：

public class TimeClient {
    public static void main(String[] args) {
        int port = 8080;
        Socket socket = null;
        BufferedReader in = null;
        PrintWriter out = null;
        try {
            socket = new Socket("127.0.0.1", port);
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            out = new PrintWriter(socket.getOutputStream(), true);
            out.println("QUERY TIME ORDER");//发送请求
            System.out.println("Send order 2 server succeed.");
            String resp = in.readLine();//回复
            System.out.println("Now is : " + resp);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (this.socket != null) {
                try {
                    this.socket.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
                this.socket = null;
            }
        }
    }
}