理解一下servlet

Java Servlet 是運行在 Web 服務器或應用服務器上的程序，它是作為來自 Web 瀏覽器或其他 HTTP 客戶端的請求和 HTTP 服務器上的數據庫或應用程序之間的中間層。

理解一下TCP/IP協議

TCP/IP不是一個協議，而是一個協議族的統稱。裏面包括了IP協議，IMCP協議，TCP協議，以及我們更加熟悉的http、ftp、pop3協議等等。電腦有了這些，就好像學會了外語一樣，就可以和其他的計算機終端做自由的交流了。

通過代碼加深一下印象。

客戶端代碼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);
            
            //向服務端輸出
            OutputStream outputStream = socket.getOutputStream();
            PrintWriter printWriter = new PrintWriter(outputStream);
            String clientName = Integer.toString( (int)(Math.random()*100) );
            printWriter.print(
 
"服務端你好，我是客戶端"+clientName+"，今天天氣不錯啊");
            printWriter.flush();
            socket.shutdownOutput();
            
            //獲取客戶端信息
            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("服務端說："+info);
            socket.shutdownInput();
            
            //關閉流對象等
            printWriter.close();
            outputStream.close();
            bufferedReader.close();
            inputStreamReader.close();
            inputStream.close();
            socket.close();
            
            
        } catch (UnknownHostException e) {
            // TODO 自動生成的 catch 塊
            e.printStackTrace();
        } catch (IOException e) {
            // TODO 自動生成的 catch 塊
            e.printStackTrace();
        }
    }
}

服務端代碼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 
        {
            //讀取客戶端的信息
            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("已經接收到客戶端的連接");
            PrintUtil.show("服務端收到客戶端信息："+infoBuilder.toString());
            PrintUtil.show("服務端地址為："+socket.getInetAddress().getHostAddress());
            socket.shutdownInput();
            //向客戶端發送信息
            OutputStream outputStream = socket.getOutputStream();
            PrintWriter printWriter = new PrintWriter(outputStream);
            printWriter.print("您好，服務端已經接收到您的信息");
            printWriter.flush();
            socket.shutdownOutput();
            //關閉需要關閉的對象
            printWriter.close();
            outputStream.close();
            bufferedReader.close();
            inputStream.close();
            socket.close();
        } 
        catch (IOException e) 
        {
            e.printStackTrace();
        }
    }
}

服務端代碼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("---服務端已經啟動，等待客戶端連接---");
            while (true) {
                Socket socket = serverSocket.accept();// 偵聽並接受到此套接字的連接,返回一個Socket對象
                ServerThread socketThread = new ServerThread(socket);
                socketThread.start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    

}

跑起來的示例

( 寫得粗糙，只做mark，後期再完善 )

一個例子加深對servlet與tcp協議的理解