simple web crawler functionality

crawler.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {

	public static void main(String[] args) {

		URL url;
		HttpURLConnection http;
		
		Pattern pattern;
		Matcher matcher;
		
		BufferedReader reader = null;
		StringBuilder sb;
		
		// taken from : http://stackoverflow.com/questions/163360/regular-expression-to-match-urls-in-java
		String urlRegex = "\\b(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]";

		try {
			url = new URL("http://perlmonks.org");
			http = (HttpURLConnection) url.openConnection();
			http.setRequestMethod("GET");		
			reader = new BufferedReader(new InputStreamReader(http.getInputStream()));
			sb = new StringBuilder();
			
			String line;
			while ((line = reader.readLine())!=null) {
				sb.append(line);
			}
			
			// the entire HTML content of the page
			//System.out.println(sb.toString());
			
			// find URLs
			pattern = Pattern.compile(urlRegex);
			matcher = pattern.matcher(sb.toString());
			System.out.println("Website URL's: ");
			int count = 0;
			while(matcher.find()) {
				++count;
				System.out.println(count + ". " + sb.toString().substring(matcher.start(), matcher.end()));
			}

		} catch (Exception ex) {
			System.out.println("Exception occured");
			ex.printStackTrace();
		} finally {
			if (reader!=null) {
				try {
					reader.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}

	}

}