CHDownloader3

//This program is used to essentially download every Cyanide and Happiness comic
//By entering the first link of the comic's page, the program will save that image to your computer
//then go to the previous page and download that picture
//It will continue until you stop the program
//v3.0
//v3.0 Changes - Ability to stop program when duplicates found
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
import java.util.Scanner;


public class CHDownloader3 {


    @SuppressWarnings("finally")
    public static void main(String[] args) throws IOException {
        System.out.println("About CHDownloader:");
        System.out.println("This program will essentially download every comic from Cyanide and Happiness");
        System.out.println("It will start at your link, then move to PREVIOUS pages");
        System.out.println("Enter the Cyanide and Happiness comic number to start with (It's found in the URL. Ex 2776)");
        Scanner userInput = new Scanner(System.in);
        int theURL = userInput.nextInt();
        System.out.println("Stop the program when a duplicate is found? Yes or No");
        String repeatQuit = userInput.next();
        System.out.println("Press Ctrl + C to stop the program");


        URL link = new URL("http://www.explosm.net/comics/"+theURL+"/");//Created the first URL using the link above
        boolean stop = false;
        while( stop == false){
            if( theURL == 14){//The comic ends at comic 15. This if statement will stop the program
                stop = true;
                System.out.println("All images downloaded");
            }
            try{
            //This section downloads the HTML page
            ReadableByteChannel rbc = Channels.newChannel(link.openStream());//Gets the html page
            FileOutputStream fos = new FileOutputStream("page.html");//Creates the output name of the html page to be saved to the computer
            fos.getChannel().transferFrom(rbc, 0, 1 << 24);
            Scanner sc = new Scanner(new FileReader("page.html"));//Takes the downloaded HTML page and sends it to a scanner






            //This section converts the html page to the string
            String contents = "";
            while(sc.hasNextLine() || sc.hasNext()){
                contents = contents + sc.nextLine() + "\n"; //Contents is the html page as a string!
            }
            sc.close();//Closes the scanner file



            //This section finds the image to download
            Scanner sc2 = new Scanner(contents);//Sends the html to a scanner
            String theImage = "";
            int counter2 = 0;//I think that the image url is on line 2 so I need a counter
            while((sc2.hasNext() || sc2.hasNextLine()) && (counter2 != 1)){
            theImage = sc2.findWithinHorizon("[h][t][t][p][:][/][/][w]?[w]?[w]?[.]?explosm.net/db/files/Comics/.*?[.][jJpPgG][pPnNiI][eE]?[gGfF]", 0);//This finds the image's url and saves it to a string
            counter2 += 1;//Adds one to my counter
            }
            //Ends finding image



            //This section determines the file extension
                String imageType = "";
                if(theImage.matches(".*[.][jJ][pP][gG]")){
                    imageType = ".jpg";
                }
                if(theImage.matches(".*[.][jJ][pP][eE][gG]")){
                    imageType = ".jpeg";
                }
                if(theImage.matches(".*[.][pP][nN][gG]")){
                    imageType = ".png";
                }
                if(theImage.matches(".*[.][gG][iI][Ff]")){
                    imageType = ".gif";
                }



            //This section saves the image itself
            URL link2 = new URL(theImage);//A new URL is created with the image's url that was found
            String chLinkFinal = "CH-" + theURL + imageType;//The string that will be used to name the file
            boolean exists = (new File(chLinkFinal)).exists();
            if(exists){
                if(repeatQuit.equals("Yes") || repeatQuit.equals("yes")){ //Quits program when duplicate is found
                    System.out.println("Duplicate found. Program Stopped.");
                    System.exit(0);
                }
                else{
                    System.out.println(chLinkFinal + " already exists. Skipping.");
                }
            }
            else{
                ReadableByteChannel rbc2 = Channels.newChannel(link2.openStream());//Gets the image
                FileOutputStream fos2 = new FileOutputStream(chLinkFinal);//The output of the file name
                fos2.getChannel().transferFrom(rbc2, 0, 1 << 24);
                System.out.println("Image Saved: " + chLinkFinal);//Prints the name of the file that is saved
            }
            theURL -= 1;//Decreases the link my 1 to capture the next image
            link = new URL("http://www.explosm.net/comics/" + theURL + "/");//Sets up the next page to be read
            }

            //Some comics using the decreasing number system don't exist. This catch loop skips them
            catch(Exception e){
                theURL -=1;
                link = new URL("http://www.explosm.net/comics/" + theURL + "/");
            }
            //This finally block allows the program to continue past the catch block
            finally{
                continue;
            }
        }
    }

}