netty学习（二）--传统的bio编程

网络编程的基本模型是Client/Server模型。也就是两个进程之间进行相互通信，当中服务端提供位置信息（

绑定ip地址和监听port），client通过连接操作向服务端监听的地址发送连接请求，通过三次握手建立连接。

假设连接成功。两方就能够通过socket进行通信。

在基于传统的同步堵塞模型开发中。ServerSocket负责绑定IP地址，启动监听port：Socket负责发起连接请求

操作。操作连接成功后，两方通过输入和输出流进行同步堵塞通信。

以下是经典的时间server代码,分析工作过程：

TimeServer代码：

package com.panther.dong.netty.bio.synchronousblockio;

import java.net.ServerSocket;
import java.net.Socket;

/**
 * server thread(corresponding to all client thread)
 * Created by panther on 15-8-11.
 */
public class TimeServer {
    public static void main(String[] args) {
        int port = 8080;
        if (args != null && args.length > 0) {
            port = Integer.valueOf(args[0]);
        }

        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();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (server != null) {
                System.out.println("the time server close");
                try {
                    server.close();
                } catch (Exception e) {

                }
                server = null;
            }
        }
    }
}

TimerServer依据传入參数设置监听的port。假设没有入參，使用默认8080port。通过构造函数创建ServerSocket

。假设port合法且没有被占用。服务端监听成功。

程序中通过一个循环来监听client的接入，假设没有client的

接入，则线程堵塞在ServerSocket的accept操作上。启动TimeServer，等待client的接入

TimeServerHandler的代码：

package com.panther.dong.netty.bio.synchronousblockio;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Date;

/**
 * listener client socket
 * Created by panther on 15-8-11.
 */
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 current = null;
            String body = null;
            while (true) {
                body = in.readLine();
                if (body == null) {
                    break;
                }
                System.out.println("The time server receive order : " + body);
                current = "QUERY TIME ORDER".equalsIgnoreCase(body) ?
                        new Date(System.currentTimeMillis()).toString() :
                        "BAD ORDER";
                out.println(current);
            }
        } catch (Exception e) {
            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;
            }
        }

    }
}

client代码TimeClient：

package com.panther.dong.netty.bio.synchronousblockio;

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

/**
 * client thread(one thread)
 * Created by panther on 15-8-13.
 */
public class TimeClient {
    public static void main(String[] args) {
        int port = 8080;
        if (args != null && args.length > 0) {
            try {
                port = Integer.valueOf(args[0]);
            } catch (Exception e) {

            }
        }
        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 (IOException e) {

        } finally {
            if (out != null) {
                out.close();
                out = null;
            }
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {

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

                }
                socket = null;
            }
        }
    }
}

执行结果：

先执行TimeServer得到结果：

在执行TimeClient。得到例如以下结果：

由上面的图可知道。TimeServer和TimeClient建立连接！

！

！！

BIO的弊端：

   每当一个新的client接入请求时，server必须创建一个新的线程处理新接入的链路。一个线程仅仅能处理一个

client的连接。在高性能server的应用领域，往往须要成千上万个client的并发连接。这样的模型无法满足高性能

、高并发接入的场景。！

。。

BIO介绍完成~~~~~~~