webserverdemo.java

Java网络编程与分布式计算, 主要分析java网络各方面的编程, 提供许多实用安全

import java.io.*;
import java.net.*;
import java.util.*;

// Chapter 8, Listing 3
public class WebServerDemo
{
  // Directory of HTML pages and other files 
  protected String docroot;
  // Port number of web server
  protected int port;
  // Socket for the web server
  protected ServerSocket ss;

  // Handler for a HTTP request
  class Handler extends Thread
  {
    protected Socket socket;
    protected PrintWriter pw;
    protected BufferedOutputStream bos;
    protected BufferedReader br;
    protected File docroot;

    public Handler(Socket _socket, String _docroot) throws Exception
    {
      socket=_socket;
	  // Get the absolute directory of the filepath
      docroot=new File(_docroot).getCanonicalFile();
    }

    public void run()
    {
      try
      {
		// Prepare our readers and writers
        br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        bos = new BufferedOutputStream(socket.getOutputStream());
        pw = new PrintWriter(new OutputStreamWriter(bos));

		// Read HTTP request from user (hopefully GET /file...... )
        String line = br.readLine();

		// Shutdown any further input
		socket.shutdownInput();

        if(line == null)
        {
          socket.close();
          return;
        }
        if(line.toUpperCase().startsWith("GET"))
        {
		  // Eliminate any trailing ? data, such as for a CGI GET request
          StringTokenizer tokens = new StringTokenizer(line," ?");
          tokens.nextToken();
          String req = tokens.nextToken();

		  // If a path character / or \ is not present, add it to the document root
		  // and then add the file request, to form a full filename
          String name;
          if(req.startsWith("/") || req.startsWith("\\"))
            name = this.docroot+req;
          else
            name = this.docroot+File.separator+req;

		  // Get absolute file path
          File file = new File(name).getCanonicalFile();

		  // Check to see if request doesn't start with our document root ....
          if(!file.getAbsolutePath().startsWith(this.docroot.getAbsolutePath()))
          {
            pw.println("HTTP/1.0 403 Forbidden");
            pw.println();
          }
		  // ... if it's missing .....
          else if(!file.exists())
          {
            pw.println("HTTP/1.0 404 File Not Found");
            pw.println();
          }
		  // ... if it can't be read for security reasons ....
          else if(!file.canRead())
          {
            pw.println("HTTP/1.0 403 Forbidden");
            pw.println();
          }
		  // ... if its actually a directory, and not a file ....
          else if(file.isDirectory())
          {
            sendDir(bos,pw,file,req);
          }
		  // ... or if it's really a file
          else
          {
            sendFile(bos, pw, file.getAbsolutePath());
          }
        }
		// If not a GET request, the server will not support it
        else
        {
          pw.println("HTTP/1.0 501 Not Implemented");
          pw.println();
        }

        pw.flush();
        bos.flush();
      }
      catch(Exception e)
      {
        e.printStackTrace();
      }
      try
      {
        socket.close();
      }
      catch(Exception e)
      {
        e.printStackTrace();
      }
   }

    protected void sendFile(BufferedOutputStream bos, PrintWriter pw, String filename) throws Exception
    {
      try
      {
        java.io.BufferedInputStream bis = new java.io.BufferedInputStream(new FileInputStream(filename));
        byte[] data = new byte[10*1024];
        int read = bis.read(data);

        pw.println("HTTP/1.0 200 Okay");
        pw.println();
        pw.flush();
        bos.flush();

        while(read != -1)
        {
          bos.write(data,0,read);
          read = bis.read(data);
        }
        bos.flush();
      }
      catch(Exception e)
      {
        pw.flush();
        bos.flush();
      }
    }

    protected void sendDir(BufferedOutputStream bos, PrintWriter pw, File dir, String req) throws Exception
    {
      try
      {
        pw.println("HTTP/1.0 200 Okay");
        pw.println();
        pw.flush();

        pw.print("<html><head><title>Directory of ");
        pw.print(req);
        pw.print("</title></head><body><h1>Directory of ");
        pw.print(req);
        pw.println("</h1><table border=\"0\">");

        File[] contents=dir.listFiles();

        for(int i=0;i<contents.length;i++)
        {
          pw.print("<tr>");
          pw.print("<td><a href=\"");
          pw.print(req);
          pw.print(contents[i].getName());
          if(contents[i].isDirectory())
            pw.print("/");
          pw.print("\">");
		  if(contents[i].isDirectory())
			pw.print("Dir -> ");
          pw.print(contents[i].getName());
          pw.print("</a></td>");
          pw.println("</tr>");
        }
        pw.println("</table></body></html>");
        pw.flush();
      }
      catch(Exception e)
      {
        pw.flush();
        bos.flush();
      }
    }
  }

  // Check that a filepath has been specified and a port number
  protected void parseParams(String[] args) throws Exception
  {
    switch(args.length)
    {
      case 1:
      case 0:
		System.err.println ("Syntax: <jvm> "+this.getClass().getName()+" docroot port");
		System.exit(0);

      default:
          this.docroot = args[0];
          this.port = Integer.parseInt(args[1]);
        break;
    }
  }

  public WebServerDemo(String[] args) throws Exception
  {
	System.out.println ("Checking for paramters");

	// Check for command line parameters
    parseParams(args);

	System.out.print ("Starting web server...... ");

	// Create a new server socket
    this.ss = new ServerSocket(this.port);

	System.out.println ("OK");

    for (;;)
    {
	  // Accept a new socket connection from our server socket
      Socket accept = ss.accept();

	  // Start a new handler instance to process the request
      new Handler(accept, docroot).start();
    }
  }

  // Start an instance of the web server running
  public static void main(String[] args) throws Exception
  {
    WebServerDemo webServerDemo = new WebServerDemo(args);
  }
}