datakom-labb/WebServer.java

//
// Multithreaded Java WebServer
// (C) 2001 Anders Gidenstam
// (based on a lab in Computer Networking: ..)
//

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

public final class WebServer
{
    public static void main(String argv[]) throws Exception
    {
	// Set port number
	int port = 0;
    
	// Establish the listening socket
	ServerSocket serverSocket = new ServerSocket(port);
	System.out.println("Port number is: "+serverSocket.getLocalPort());

    
	// Wait for and process HTTP service requests
	while (true) {
	    // Wait for TCP connection
	    Socket requestSocket = serverSocket.accept();
	    requestSocket.setSoLinger(true, 5);
        
	    // Create an object to handle the request
	    HttpRequest request  = new HttpRequest(requestSocket);
        
	    //request.run()

	    // Create a new thread for the request
	    Thread thread = new Thread(request);

	    // Start the thread
	    thread.start();
	}
    }
}

final class HttpRequest implements Runnable
{
    // Constants
    //   Recognized HTTP methods
    final static class HTTP_METHOD
    {
	final static String GET  = "GET";
	final static String HEAD = "HEAD";
	final static String POST = "POST";
    }

    final static String HTTPVERSION = "HTTP/1.0";
    final static String CRLF = "\r\n";
    final static String Response200 = HTTPVERSION + " 200 OK "+CRLF;
    final static String Response404 = HTTPVERSION + " 404 Not Found "+CRLF;
    final static String Response400 = HTTPVERSION + " 400 Bad Request "+CRLF;
    final static String Response501 = HTTPVERSION + " 501 Not Implemented "+CRLF;
    final static String Location = " datalabb "+CRLF;

    Socket socket;

    // Constructor
    public HttpRequest(Socket socket) throws Exception
    {
	this.socket = socket;
    }

    // Implements the run() method of the Runnable interface
    public void run()
    {
	try {
	    processRequest();
	} catch (Exception e) {
	    System.out.println(e);
	}
    }

    // Process a HTTP request
    private void processRequest() throws Exception
    {
        // Get the input and output streams of the socket.
	InputStream ins       = socket.getInputStream();
	DataOutputStream outs = new DataOutputStream(socket.getOutputStream());

	// Set up input stream filters
	BufferedReader br = new BufferedReader(new InputStreamReader(ins));
	Date d = new Date();

	// Get the request line of the HTTP request
	String requestLine = br.readLine();
    
	// Display the request line
	System.out.println();
	System.out.println("Request:");
	System.out.println("  " + requestLine);

	String[] tokens = requestLine.split("\\s+");
	//System.out.println("-->"+tokens.length);
	String Request = tokens[0];
	if(tokens.length != 3){
	    System.out.println("Wrong number of arguments in request!");
	    outs.writeChars(Response400+Location+getDateString(d));
	}
	else if(tokens[1].charAt(0) != '/'){
	    System.out.println("illegal url");
	    outs.writeChars(Response501+Location+getDateString(d));
	}
	else if(Request.equals(HTTP_METHOD.GET) || Request.equals(HTTP_METHOD.HEAD)){
	    FileInputStream filein;
	    try{
		File f = new File("." +tokens[1]);
		filein = new FileInputStream(f);
		String response = createHeader(d,f);
		outs.writeChars(response);
		if(Request.equals(HTTP_METHOD.GET))
		   sendBytes(filein,outs);
	    }
	    catch (FileNotFoundException e){
		outs.writeChars(Response404+getDateString(d));
	    }
	} else if(Request.equals(HTTP_METHOD.POST)){
	    outs.writeChars(Response501+getDateString(d));
	}
	else
	    outs.writeChars(Response400+getDateString(d));
	
	
	// Close streams and sockets
	outs.close();
	br.close();
	socket.close();
    }

    private String getDateString(Date d){
	return "Date: "+d.toString()+CRLF;
    }

    private String createHeader(Date d, File f){
	String response = Response200;
	response += getDateString(d);
	response += "Location: " + f.getName() +CRLF;
	response += "Server: Labbserver" + CRLF;
	response += "Allow: " + HTTP_METHOD.GET + " " + HTTP_METHOD.HEAD+CRLF;
	response += "Content-Length: " + f.length() +CRLF;
	response += "Content-Type: " + contentType(f.getName()) +CRLF;
	response += "Last-Modified: " + new Date(f.lastModified()).toString() +CRLF;
	return response;

    }
    private static void sendBytes(FileInputStream  fins,
				  OutputStream     outs) throws Exception
    {
	// Coopy buffer
	byte[] buffer = new byte[1024];
	int    bytes = 0;

	while ((bytes = fins.read(buffer)) != -1) {
	    outs.write(buffer, 0, bytes);
	}
    }

    private static String contentType(String fileName)
    {
	if (fileName.toLowerCase().endsWith(".htm") ||
	    fileName.toLowerCase().endsWith(".html")) {
	    return "text/html";
	} else if (fileName.toLowerCase().endsWith(".gif")) {
	    return "image/gif";
	} else if (fileName.toLowerCase().endsWith(".jpg")) {
	    return "image/jpeg";
	} else {
	    return "application/octet-stream";
	}
    }
}