/**
 * class LozinskiRandomImage extends HttpServlet - Version 2.0
 * 
 * This class is used to generate random images within JSP and Servlets.
 * 
 * INSTALLATION:
 * 1) Download this text file to your server and save as "LozinskiRandomImage.java"
 * 2) Edit the value for the private variable "imageDirectory" from "./gfx/" to whatever 
 *    default directory you would like. It should end with a trailing slash "/" character!
 * 3) Compile the class
 * 4) Install the class on your server in the specified class-path location
 * 
 * RUNNING/USING:
 * 1) You will need to import the compiled class file into your JSP page similar to the following:
 * <%@ page import="LozinskiRandomImage;" %>
 * 2) Use the appropriate constructors and methods.
 * 
 * The random images can be returned one of two ways:
 * 	1) As an HTML IMG tag revealing the name of the random image
 * 	OR
 * 	2) As raw binary data when invoked from an HTML IMG tag as a servlet.
 * 
 * Simple usage examples respectively:
 * 
 * Example 1)
 * 
 * <% 
 * :
 * : <other code>
 * :
 * LozinskiRandomImage lri = new LozinskiRandomImage(getServletConfig().getServletContext(),"gfx/"); 
 * :
 * : <other code>
 * :
 * %>
 * 
 * Any HTML/JSP tags
 * 
 * <%= lri.getRandomImageTag() %>
 * 
 * 
 * Example 2)
 * 
 * <IMG SRC="http://www.yourdomain.com/LozinskiRandomImage" ALT="Random Image">
 * 
 * HISTORY:
 * 06/05/04	2.0	Original release
 * 
 * AUTHOR:
 * http://www.davelozinski.com/scripts/
 */
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class LozinskiRandomImage extends HttpServlet {

	//The URL to the directory where the "Random Images"
	//are kept. This will only need to be changed if
	//1) The directory isn't correct 
	// AND EITHER
	//2) The Constructor is used that doesn't require the directory OR
	//3) This is called as a servlet
	private String imageDirectory = "./gfx/";
	private ServletContext application;

	/**
	 * LozinskiRandomImage(ServletContext a, String d)
	 * 
	 * Constructor when this class is not used as a servlet. 
	 * 
	 * First parameter is the ServletContext object passed in.
	 * Second parameter is the relative directory path where the random images are located.
	 * 
	 * Examples:
	 * <% LozinskiRandomImage lri = new LozinskiRandomImage(getServletConfig().getServletContext(),"gfx/"); %>
	 * <% LozinskiRandomImage lri = new LozinskiRandomImage(getServletConfig().getServletContext(),"../../RandomImages/"); %>
	 */	
	public LozinskiRandomImage(ServletContext a, String d) {
		imageDirectory = d;
		application = a;
	}
	
	/**
	 * LozinskiRandomImage(ServletContext a)
	 * 
	 * Constructor when this class is not used as a servlet. 
	 * 
	 * Parameter is the ServletContext object passed in.
	 * 
	 * Example:
	 * <% LozinskiRandomImage lri = new LozinskiRandomImage(getServletConfig().getServletContext()); %>
	 */	
	public LozinskiRandomImage(ServletContext a) {
		application = a;
	}

	/**
	 * LozinskiRandomImage()
	 * 
	 * Constructor when this class is used as a servlet ONLY, and should not be called. 
	 * 
	 * Example:
	 * <IMG SRC="http://www.yourdomain.com/LozinskiRandomImage" ALT="Random Image">
	 */	
	public LozinskiRandomImage() {
	}

	//This method does the work when called as a servlet.
	//
	//It creates some variables.
	//Reads the specified directory where the random images are kept,
	//filtering for gif and jpg images only.
	//
	//If images are found, then it responds with the content-type headers,
	//and finally writes out the binary image data.
	public void service(javax.servlet.http.HttpServletRequest request, 
			javax.servlet.http.HttpServletResponse response) 
			throws javax.servlet.ServletException, java.io.IOException {		

		application = getServletConfig().getServletContext();				
		File dir = new File(application.getRealPath(imageDirectory));
		byte[] buf = new byte[1024];
		int x=0;		

		//Obtain the list of files						
		FilenameFilter imageFiles = new FilenameFilter() {			
			public boolean accept(File path, String name) {				
				return (name.endsWith("gif") || name.endsWith("jpg") || name.endsWith("jpeg"));			
			}		
		};		
		
		File[] files = dir.listFiles(imageFiles);
		if (files.length > 0) {	
			int randomNum = new Random().nextInt(files.length);		
			OutputStream os = response.getOutputStream();				
			BufferedInputStream in = new BufferedInputStream(new FileInputStream(files[randomNum]));		
		
			//Print the response headers
			response.setHeader("Pragma", "Pragma: no-cache");		
			if (files[randomNum].toString().endsWith("gif")) {		
				response.setContentType("Content-type: image/gif");		
			} else if (files[randomNum].toString().endsWith("jpg")) {
				response.setContentType("Content-type: image/jpg");		
			} else if (files[randomNum].toString().endsWith("jpeg")) {
				response.setContentType("Content-type: image/jpeg");		
			}
			//Write the binary data from the image file
			while ((x = in.read(buf, 0, buf.length)) != -1) {			
				os.write(buf, 0, x);		
			}		
			os.flush();		
			os.close();		
			in.close();	
		}
	} //service
	
	/**
	 * String getRandomImageTag ()
	 * 
	 * Returns an HTML IMG tag specifying an image for the URL.
	 * 
	 * Otherwise, returns an error message.
	 * 
	 * Example:
	 * <% LozinskiRandomImage lri = new LozinskiRandomImage(getServletConfig().getServletContext(),"gfx/"); %>
	 * <%= lri.getRandomImageTag() %>
	 */	
	public String getRandomImageTag () {
		
		File dir = new File(application.getRealPath(imageDirectory));
		String msg = "";//#Either the IMG tag or message to be returned.

		if (dir.isDirectory()) {
			FilenameFilter imageFiles = new FilenameFilter() {			
				public boolean accept(File path, String name) {				
					return (name.endsWith("gif") || name.endsWith("jpg") || name.endsWith("jpeg"));			
				}		
			};		
			File[] files = dir.listFiles(imageFiles);		
			if (files.length > 0) {
				int randomNum = new Random().nextInt(files.length);		
				msg = "<IMG SRC=\"" + imageDirectory + files[randomNum].getName().toString() + "\" ALT=\"\">";
			} else {
				msg = "No random images located in \"" + dir.toString() + "\"";
			}
		} else {
			msg = "\"" + dir.toString() + "\" does not appear to be a valid directory!";
		}
		return msg;
	} //getRandomImageTag ()
	
	/**
	 * String getImageDirectory()
	 * 
	 * Returns the current image directory where the random images are stored.
	 * 
	 * Example:
	 * <% LozinskiRandomImage lri = new LozinskiRandomImage(getServletConfig().getServletContext()),"gfx/"); %>
	 * <%= lri.getImageDirectory() %>
	 */
	public String getImageDirectory() {
		return imageDirectory;
	}
	
	/**
	 * void setImageDirectory(String d)
	 * 
	 * Sets the random image directory to use to the string passed in.
	 * 
	 * Example:
	 * LozinskiRandomImage lri = new LozinskiRandomImage(getServletConfig().getServletContext());
	 * lri.setImageDirectory("gfx/");
	 * lri.getRandomImageTag();
	 */
	public void setImageDirectory(String d) {
		imageDirectory = d;
	}

} //LozinskiRandomImage