Tomcat学习笔记（一）一个简单的Web服务器

package com.socket.httpservertest;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
public class HttpServer {
     public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webroot";
     // shutdown command
     private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
     // the shutdown command received
     private boolean shutdown = false;
     public static void main(String[] args)
     {
           HttpServer server = new HttpServer();
           server.await();
           
     }
     public void await() {
     //   System.out.println(System.getProperty("user.dir"));
           ServerSocket serverSocket = null;
           int port = 8080;
           try {
                serverSocket = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1"));
           } catch (IOException e) {
                e.printStackTrace();
                System.exit(1);
           }
           while (!shutdown) {
                Socket socket = null;
                InputStream input = null;
                OutputStream output = null;
                try {
                     //接收了客户端发来的请求，否则一致是等待状态
                     socket = serverSocket.accept();
                     input = socket.getInputStream();
                     output = socket.getOutputStream();
                     // create Request object and parse
                     Request request = new Request(input);
                     request.parse(); //从请求中读取内容
                     // create Response object
                     Response response = new Response(output);
                     response.setRequest(request);
                     response.sendStaticResource();
                     // Close the socket
                     socket.close();
                     //check if the previous URI is a shutdown command
                     shutdown = request.getUri().equals(SHUTDOWN_COMMAND);
                }catch (Exception e)
                {
                     e.printStackTrace ();
                     continue;
                }
           }
    }
}

package com.socket.httpservertest;
import java.io.IOException;
import java.io.InputStream;
public class Request {
     private InputStream input;
     private String uri;
     public Request(InputStream input)
     {
           this.input = input;
     }
     
     public void parse() {
           // Read a set of characters from the socket
           StringBuffer request = new StringBuffer(2048);
           int i;
           byte[] buffer = new byte[2048];
           try {
                i = input.read(buffer); //将从输入流取2048长度的内容存到buffer字节数组中，如果内容不到2048，数组其他空间剩余空着
           } catch (IOException e) {
                e.printStackTrace();
                i = -1;
           }
           
           for (int j=0; j<i; j++)
           {
                request.append((char) buffer[j]);
           }
           System.out.print(request.toString());
           uri = parseUri(request.toString());
     }
     
     private String parseUri(String requestString) {
           int index1, index2;
           index1 = requestString.indexOf(‘ ‘);
           /*
            * http请求行的结构:方法 统一资源标识符（URI） 协议/版本(它们之间以空格分隔)
            * 例如：POST //examples/default.jsp HTTP/1.1
            */
           if (index1 != -1) {// index1 == -1表示没找到
                     index2 = requestString.indexOf(‘ ‘, index1 + 1);//从index+1位置开始寻找‘ ’
                     if (index2 > index1)
                     return requestString.substring(index1 + 1, index2);
                }
           return null;
     }
     
     public String getUri()
     {
           return uri;
     }
}