模拟tomcat工作原理

本文也是参考了网上的资料，加上我自己的整理得出的。

httpserver原理：服务器端 打开一个socket，一直处在监听tomcat指定的 ip 的指定端口，一旦有访问的，就开启一个线程去处理，代码如下：

-------------------------------server：

package com.kaobian;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import com.session.HttpSession;

public class HttpServer {
    public static void main(String[] args) {
        try {
            ServerSocket server = new ServerSocket(8888);
            while (true) {
                Socket socket = server.accept();
                HttpSession session = new HttpSession(socket);
                new Thread(session).start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

---------------------------------处理线程

package com.session;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.Socket;

import com.config.Config;

public class HttpSession implements Runnable {
    private String path = Config.getConfig().getPath();
    private Socket socket ;

    public HttpSession(Socket socket){
        super();
        this.socket = socket;
    }

    public void run() {
         try {
            BufferedReader br = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            OutputStream out = this.socket.getOutputStream();
            String command = null;
            while((command = br.readLine()) != null){
                System.out.println("浏览器的指令:"+command);
                if(command.length() <3){
                    break;
                }
                String result = command.substring(0,3);
                if(result.equalsIgnoreCase("GET")){
                    int begin = command.indexOf("/")+1;
                    int end   = command.lastIndexOf(" ");
                    String fileName = command.substring(begin,end);
                    doGet(fileName,out);
                }
               
            }
            out.close();
            br.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void doGet(String fileName, OutputStream out) {
        File file = new File(path+fileName);
        if(!file.isDirectory()){
            if(!file.exists()){
                file = new File(path + Config.getConfig().getDefaultPage());   
            }
        }else {
            file = new File(path +  Config.getConfig().getDefaultPage());
        }
        InputStream is  = null;
        try {
            is = new FileInputStream(file);
            byte[] data  =new byte[1024];
            int    len = 0;
            while((len = is.read(data)) != -1){
                out.write(data,0,len);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(is != null){
               try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }finally{
                    is = null;
                }
            }
        }
       
    }

}

---------------------------读取配置文件

package com.config;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

public class Config {
   
    private String  path ;
    private String  defaultPage;
    private static Config config ;
   
    public static Config getConfig(){
        if(config == null){
            config = new Config();
            config.init();
        }
        return config;
    }
   
    private void init(){
        Properties properties = new Properties();
        try {
            InputStream reader = new FileInputStream(new File("config.properties"));
            properties.load(reader);
            this.path = properties.getProperty("path");
            this.defaultPage = properties.getProperty("defaultIndex");
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
   
    private Config(){
    }
   
    public String getPath() {
        return path;
    }
    public void setPath(String path) {
        this.path = path;
    }
    public String getDefaultPage() {
        return defaultPage;
    }
    public void setDefaultPage(String defaultPage) {
        this.defaultPage = defaultPage;
    }
   
}

------------------配置文件要放到工程的根目录下，要不然自行修改属性文件的位置

path=c://
defaultIndex=div.html

评论

2 楼 kaobian 2011-07-18  

cheney_love 写道

while (true) {
                Socket socket = server.accept();
                HttpSession session = new HttpSession(socket);
                new Thread(session).start();
            }

这方法不是在不停的创建HttpSession 吗

不是，这个方法只有在客户端有请求的时候 才会去创建一个线程去执行，server.accept();
是一个阻塞式的执行，他一直 出去监听状态，只有有访问的时候才会实例化一个socket

1 楼 cheney_love 2011-07-18  

while (true) {
                Socket socket = server.accept();
                HttpSession session = new HttpSession(socket);
                new Thread(session).start();
            }

这方法不是在不停的创建HttpSession 吗