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：

watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="">

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~~~~~~~