一个例子加深对servlet与tcp协议的理解

理解一下servlet

Java Servlet 是运行在 Web 服务器或应用服务器上的程序，它是作为来自 Web 浏览器或其他 HTTP 客户端的请求和 HTTP 服务器上的数据库或应用程序之间的中间层。

理解一下TCP/IP协议

TCP/IP不是一个协议，而是一个协议族的统称。里面包括了IP协议，IMCP协议，TCP协议，以及我们更加熟悉的http、ftp、pop3协议等等。电脑有了这些，就好像学会了外语一样，就可以和其他的计算机终端做自由的交流了。

通过代码加深一下印象。

客户端代码Client.java

package com.java.tcp;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

import com.java.util.PrintUtil;

public class Client
{
    public static void main(String[] args)
    {
        try
        {
            Socket socket = new Socket("localhost",8888);

            //向服务端输出
            OutputStream outputStream = socket.getOutputStream();
            PrintWriter printWriter = new PrintWriter(outputStream);
            String clientName = Integer.toString( (int)(Math.random()*100) );
            printWriter.print("服务端你好，我是客户端"+clientName+"，今天天气不错啊");
            printWriter.flush();
            socket.shutdownOutput();

            //获取客户端信息
            InputStream inputStream = socket.getInputStream();
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String temp = null;
            StringBuilder info = new StringBuilder();
            while( (temp = bufferedReader.readLine()) !=null )
            {
                info.append(temp);
            }
            PrintUtil.show("服务端说："+info);
            socket.shutdownInput();

            //关闭流对象等
            printWriter.close();
            outputStream.close();
            bufferedReader.close();
            inputStreamReader.close();
            inputStream.close();
            socket.close();

        } catch (UnknownHostException e) {
            // TODO 自动生成的 catch 块
            e.printStackTrace();
        } catch (IOException e) {
            // TODO 自动生成的 catch 块
            e.printStackTrace();
        }
    }
}

服务端代码ServerThread.java

import com.java.util.PrintUtil;

public class ServerThread extends Thread
{
    private Socket socket;

    public ServerThread(Socket socketIn)
    {
        this.socket = socketIn;
    }

    public void run()
    {
        try
        {
            //读取客户端的信息
            InputStream inputStream = socket.getInputStream();
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String temp = null;
            StringBuilder infoBuilder = new StringBuilder();
            while((temp = bufferedReader.readLine()) !=null)
            {
                infoBuilder.append(temp);
            }
            PrintUtil.show("已经接收到客户端的连接");
            PrintUtil.show("服务端收到客户端信息："+infoBuilder.toString());
            PrintUtil.show("服务端地址为："+socket.getInetAddress().getHostAddress());
            socket.shutdownInput();
            //向客户端发送信息
            OutputStream outputStream = socket.getOutputStream();
            PrintWriter printWriter = new PrintWriter(outputStream);
            printWriter.print("您好，服务端已经接收到您的信息");
            printWriter.flush();
            socket.shutdownOutput();
            //关闭需要关闭的对象
            printWriter.close();
            outputStream.close();
            bufferedReader.close();
            inputStream.close();
            socket.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }
}

服务端代码Server.java

package com.java.tcp;

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

import com.java.util.PrintUtil;

public class Server
{
    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(8888);
            PrintUtil.show("---服务端已经启动，等待客户端连接---");
            while (true) {
                Socket socket = serverSocket.accept();// 侦听并接受到此套接字的连接,返回一个Socket对象
                ServerThread socketThread = new ServerThread(socket);
                socketThread.start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

跑起来的示例

( 写得粗糙，只做mark，后期再完善 )