How Tomcat Works 读书笔记(第一章)

进来在看《How Tomcat Works》这本书，将读书笔记贴在这里，好记性不如烂笔头。
最简单的一个服务器，一个很简单的结果。
HttpServer构建ServerSocket，每次当请求到来是创建一个Socket,并创建Request，Response对象，根据URI读取位于WebRoot底下的静态资源。
类如下：

package com.ex01.pyrmont;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;

public class HttpServer {
	public final static String WEB_ROOT = "webRoot";
	
	public final static String SHUT_DOWN = "/SHUTDOWN";
	
	private boolean shutdown = false;
	
	public static void main(String[] args) {
		HttpServer httpServer = new HttpServer();
		httpServer.await();
	}
	
	public void await() {
		int port = 8080;
		ServerSocket serverSocket = null;
			try {
				serverSocket = new ServerSocket(port,1,InetAddress.getByName("127.0.0.1"));
			} catch (UnknownHostException e) {
				e.printStackTrace();
				System.exit(1);
			} catch (IOException e) {
				System.exit(1);
			}
		Socket socket = null;
		InputStream input;
		OutputStream out;
		
		while(!shutdown){
			try {
				socket = serverSocket.accept();
				input = socket.getInputStream();
				out = socket.getOutputStream();
				Request request = new Request(input);
				request.parse();
				
				Response response = new Response(out);
				response.setRequest(request);
				response.sendStaticResource();
				
				input.close();
				out.close();
				socket.close();
				
				shutdown = request.getUri().equals(SHUT_DOWN);
			} catch (IOException e) {
				e.printStackTrace();
			} 
		}
		
		
	}
}

package com.ex01.pyrmont;

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

public class Request {
	private InputStream input;
	
	private String uri;
	
	public Request() {}
	
	public Request(InputStream input){
		this.input = input;
	}
	
	public void parse(){
		StringBuffer buffer =  new StringBuffer(2048);
		byte[] buf = new byte[2048];
		int len = 0;
		try {
			len = input.read(buf);
		} catch (IOException e) {
			len = 0;
			e.printStackTrace();
		}
		for(int i = 0; i < len; i++){
			buffer.append((char)buf[i]);
		}
		uri = parseUri(buffer.toString());
	}
	
	private String parseUri(String uriStr){
		int spaceIndex = uriStr.indexOf(" ");
		if(spaceIndex != -1){
			int spaceSecondIndex = uriStr.indexOf(" ", spaceIndex + 1);
			if(spaceSecondIndex > spaceIndex){
				return uriStr.substring(spaceIndex + 1,spaceSecondIndex);
			}
		}
		return null;
	}
	
	public String getUri(){
		return uri;
	}
}

package com.ex01.pyrmont;

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

public class Response {
	public final static int BUFFER_SIZE = 2048;
	private OutputStream out;
	private Request request;

	public Response() {}

	public Response(OutputStream out) {
		this.out = out;
	}

	public void sendStaticResource() throws IOException {
		String uri = request.getUri();
		FileInputStream fis = null;
		File file = new File(HttpServer.WEB_ROOT, uri);
		if (file.exists()) {
			fis = new FileInputStream(file);
			byte[] buf = new byte[BUFFER_SIZE];
			int len = fis.read(buf);
			while (len != -1) {
				out.write(buf, 0, len);
				len = fis.read(buf);
			}
		} else {
			// file not found
			String errorMessage = "HTTP/1.1 404 File Not Found\r\n"
					+ "Content-Type: text/html\r\n" + "Content-Length: 23\r\n"
					+ "\r\n" +

					"<h1>File Not Found</h1>";
			out.write(errorMessage.getBytes());
		}
		if(fis != null){
			fis.close();
		}
	}

	public void setRequest(Request request) {
		this.request = request;
	}
}

上面的程序比较简单，但也有一定的问题：
1. 比如获取URI的过程，感觉就很不好，没有一定的容错性
2. 异常的处理比较混乱等
虽然这些tomcat都得到了很好的处理，并且有很多值得借鉴的地方，但是思考一下到后面估计和它有一定的共鸣。

源码在google这里面有http://www.google.com/codesearch/p?hl=en&sa=N&ct=rx&cd=9#X8Q3DKkF7lI/HowTomcatWorks/:java