Working with URLs in Java

In this blog post, let's see how we could play around with URLs (Uniform Resource Locator) or simply the address to any website found on the internet, within a java program.

Basic Information about the Website

To start with, we'll be needing java.net.* set of classes. Then a URL object to specify the URL we need to play with:

URL urlObject = new URL("https://nandunb.wordpress.com");

Then let's get some of the basic information about the website, like the protocol, the port connected to and it's host:

System.out.println("Protocol: " + url.getProtocol());
System.out.println("Port: " + url.getPort());
System.out.println("Host: " + url.getHost());

Displaying the content of the Website (HTML)

Moving on, to display the content or the HTML content of the website, we'll need to create a URLConnection type object:

URLConnection conn = url.openConnection();

Then we will check if any content is available using getContentLength(), and use an InputStream to read the content:

InputStream urlInput = conn.getInputStream();
while ((c = urlInput.read()) != -1) {
    System.out.print((char) c);
}
urlInput.close();

Complete Code

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

public class URLProg {
    public static void main(String[] args) throws Exception {
        URL url = new URL("http://www.google.com");
        System.out.println("Basic Information: ");
        System.out.println("Protocol: " + url.getProtocol());
        System.out.println("Port: " + url.getPort());
        System.out.println("Host: " + url.getHost());

        URLConnection conn = url.openConnection();
        int c;
        if (conn.getContentLength() != 0) {
            System.out.println("Content: ");
            InputStream urlInput = conn.getInputStream();
            while ((c = urlInput.read()) != -1) {
                System.out.print((char) c);
            }
            urlInput.close();
        } else {
            System.out.println("Sorry. No content!");
        }
    }
}