1. BIO编程——读netty权威指南笔记一

1.TimeServer.java

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * @author
 * @Description:
 * @Date: Created in 11:26 2018/6/28
 * @Modified By:
 */
public class TimeServer {


    public static void main(String[] args) throws IOException{
        int port = 8888;
        if(args != null && args.length >0){
            try{
                port = Integer.valueOf(args[0]);
            }catch (NumberFormatException e){
                //采用默认值
            }
        }

        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();
                new Thread(new TimeServerHandler(socket)).start();
            }
        }finally {
            if(server != null){
                System.out.println("the time server close");
                server.close();
                server = null;
            }

        }
    }
}

1. TimeServerHandler.java

/**
 * @author
 * @Description:
 * @Date: Created in 11:39 2018/6/28
 * @Modified By:
 */
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{
            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();
                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);
            }
        }catch (Exception e){
            e.printStackTrace();
            if(in != null){
                try {
                    in.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }

            if(out != null){
                out.close();
                out = null;
            }
            if(this.socket != null){
                try {
                    this.socket.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
                this.socket = null;
            }
        }
    }
}

1. TimeClient.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * @author ${user}
 * @Description:
 * @Date: Created in 11:51 2018/6/28
 * @Modified By:
 */
public class TimeClient {

    public static void main(String[] args) {
        int port = 8888;
        if(args != null && args.length >0){
            try{
                port = Integer.valueOf(args[0]);
            }catch (NumberFormatException e){
                //采用默认值
            }
        }

        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");
            System.out.println("send order 2 server succeed.");
            String resp = in.readLine();
            System.out.println("Now is :"+resp);
        }catch (Exception e){
            //不需要处理
            //e.printStackTrace();
        }finally {
            if(out != null){
                out.close();
                out = null;
            }
            if(in != null){
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                in = null;
            }

            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                socket = null;
            }

        }
    }
}

测试结果：

服务器端：
the time server is start in port :8888
the time server receive order:QUERY TIME ORDER
the time server receive order:QUERY TIME ORDER
the time server receive order:QUERY TIME ORDER

客户端：
send order 2 server succeed.
Now is :Thu Jun 28 11:57:35 CST 2018

BIO的缺点：
同步阻塞式IO主要的问题在于每当有一个新的客户端请求接入时，服务器必须创建一个新的县城处理新接入的客户端链路，一个线程只能处理一个客户端请求。在高性能服务器应用领域，往往需要面向成千上万个客户端的并发链接，这种模型显然无法满足高性能，高并发接入的场景。

为了改进一线程一链接模型，可以通过线程池或者消息队列实现1个或多个线程处理N个客户端的模型，由于它的底层通信机制依然使用同步阻塞IO，所以被称为“伪异步”.