Java Web 服务器原理

写下这编文章只是为了让自己不忘记以前学过的知识，下面是基于Socket来完成浏览器的访问，就类似于tomcat（不过tomcat比我功能更全更强大），那下面来看代码：

很简单 先由 HttpServer 来接受浏览器的问访问之后就交给HttpThread类来响应。

package com.zx;

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

/**
 * @author zhouxiang 
 * @version Feb 21, 2013 10:22:55 AM
 */
public class HttpServer {
	// 默认ROOT文件夹
	public static String ROOT = "./wwwroot";
	// 默认文件的文件名
	public static String defaultPage = "index.html";
	
	public static void main(String[] args) throws IOException {
		ServerSocket server = new ServerSocket(8000);
		while(true){
			// 阻塞，等待浏览器的连接
			Socket socket = server.accept();
			System.out.println("Accept Connection.....\n");
			// 启动服务线程
			new HttpThread(socket).start();
		}
	}
}

HttpThread获取到io流并作出响应

package com.zx;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

/**
 * @author zhouxiang
 * @version Feb 21, 2013 10:33:52 AM
 */
public class HttpThread extends Thread {

	private Socket socket;

	public HttpThread(Socket socket) {
		this.socket = socket;
	}

	@Override
	public void run() {
		InputStream inputStream = null;
		OutputStream outputStream = null;
		try {
			inputStream = this.socket.getInputStream();
			outputStream = this.socket.getOutputStream();
			Receiver receiver = new Receiver(inputStream);
			// 取得浏览器发过来的URL请求
			String sURL = receiver.parese();
			if (sURL.equals("/")) {
				sURL = HttpServer.defaultPage;
			}
			Answer ans = new Answer(outputStream);
			ans.send(sURL);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			try {
				if (inputStream != null) {
					inputStream.close();
				}
				if(outputStream != null){
					outputStream.close();
				}
				if(socket != null ){
					socket.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}

Receiver这个类获主要取浏览器访问的地址

package com.zx;

import java.io.IOException;
import java.io.InputStream;

/**
 * @author zhouxiang 
 * @version Feb 21, 2013 10:40:39 AM
 */
public class Receiver {

	InputStream inputStream = null;
	public Receiver(InputStream inputStream) {
		this.inputStream = inputStream;
	}

	/**
	 * 这个方法的目的是将URL请求的文件返回
	 * @return
	 */
	public String parese(){
		StringBuffer receiveStr = new StringBuffer(2048);
		int i = 0;
		byte[] bytes = new byte[2048];
		try {
			//从socket读出数据
			i = inputStream.read(bytes);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			//e.printStackTrace();
			// 读出空数据
			System.out.println("读取流异常......");
			i = -1;
		}
		System.out.println("读取的字节长度："+""+i);
		for(int j = 0 ; j < i ; j++){
			// 读出数据以字符方式保存到receiveStr
			receiveStr.append((char)bytes[j]);
		}
		return getUri(receiveStr.toString());
	}

	/**
	 * 将收到的HTTP协议数据包分解，取出文件名
	 * @param receiveStr
	 * @return
	 */
	private String getUri(String receiveStr) {
		int index1,index2;
		index1 = receiveStr.indexOf(' ');
		if(index1 != -1){
			index2 = receiveStr.indexOf(' ',index1 + 1);
			if(index2 > index1){
				return receiveStr.substring(index1 + 1, index2);
			}
		}
		return null;
	}

}

Answer这个就是响应类了

package com.zx;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;

/**
 * @author zhouxiang
 * @version Feb 21, 2013 11:54:10 AM
 */
public class Answer {

	OutputStream out = null;

	public Answer(OutputStream outputStream) {
		this.out = outputStream;
	}

	public void send(String pageFile) {
		// TODO Auto-generated method stub
		byte[] bytes = new byte[2048];
		FileInputStream fis = null;
		try {
			File file = new File(HttpServer.ROOT, pageFile);
			if (file.exists()) {
				fis = new FileInputStream(file);
				int ch = fis.read(bytes, 0, 2048);
				String sBody = new String(bytes);
				String sendMessage = "HTTP/1.1 200 OK\r\n"+"Content-Type: text/html\r\n"+"Content-Length: "+ch+"\r\n"+
				"\r\n"+sBody;
				out.write(sendMessage.getBytes());
			}
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			if(fis != null){
				try {
					fis.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	}

}

代码很简单主要就是了解下，刚学习服务器的同学现在应该不会对服务器有什么距离了吧！