Use JAVA to implement a simple Http Server

SimpleHttpServer. java

import java.io.FileInputStream;import java.io.IOException;import java.net.InetSocketAddress;import java.net.Socket;import java.nio.ByteBuffer;import java.nio.CharBuffer;import java.nio.channels.FileChannel;import java.nio.channels.ServerSocketChannel;import java.nio.channels.SocketChannel;import java.nio.charset.Charset;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class SimpleHttpServer {private int port=8080;  private ServerSocketChannel serverSocketChannel = null;  private ExecutorService executorService;  private static final int POOL_MULTIPLE = 4;  public SimpleHttpServer() throws IOException {    executorService= Executors.newFixedThreadPool(    Runtime.getRuntime().availableProcessors() * POOL_MULTIPLE);    serverSocketChannel= ServerSocketChannel.open();    serverSocketChannel.socket().setReuseAddress(true);    serverSocketChannel.socket().bind(new InetSocketAddress(port));    System.out.println("ddd");  }  public void service() {    while (true) {      SocketChannel socketChannel=null;      try {        socketChannel = serverSocketChannel.accept();        executorService.execute(new Handler(socketChannel));      }catch (IOException e) {         e.printStackTrace();      }    }  }  public static void main(String args[])throws IOException {    new SimpleHttpServer().service();  }  class Handler implements Runnable{  private SocketChannel socketChannel;  public Handler(SocketChannel socketChannel){    this.socketChannel=socketChannel;  }  public void run(){    handle(socketChannel);  }  public void handle(SocketChannel socketChannel){    try {        Socket socket=socketChannel.socket();        System.out.println("ddd" +        socket.getInetAddress() + ":" +socket.getPort());         ByteBuffer buffer=ByteBuffer.allocate(1024);         socketChannel.read(buffer);         buffer.flip();         String request=decode(buffer);         System.out.print(request);           StringBuffer sb=new StringBuffer("HTTP/1.1 200 OK\r\n");         sb.append("Content-Type:text/html\r\n\r\n");         socketChannel.write(encode(sb.toString()));         FileInputStream in;                  String firstLineOfRequest=request.substring(0,request.indexOf("\r\n"));         if(firstLineOfRequest.indexOf("login.htm")!=-1)            in=new FileInputStream("/Users/tokou/Documents/post.html");         else            in=new FileInputStream("/Users/tokou/Documents/post.html");         FileChannel fileChannel=in.getChannel();         fileChannel.transferTo(0,fileChannel.size(),socketChannel);         fileChannel.close();      }catch (Exception e) {         e.printStackTrace();      }finally {         try{           if(socketChannel!=null)socketChannel.close();         }catch (IOException e) {e.printStackTrace();}      }  }  private Charset charset=Charset.forName("GBK");  public String decode(ByteBuffer buffer){      CharBuffer charBuffer= charset.decode(buffer);    return charBuffer.toString();  }  public ByteBuffer encode(String str){      return charset.encode(str);  } }}