Working with URL in Java

URL stands for Uniform Resource Locator. Every webpage or resource on the Internet has a unique URL by which it is recognized. If you want to develop a web-based application, your program needs to be able to interact with URLs as well as manipulate if required.

Components of an URL

A general form of an URL is as follows: protocol://host:port/path?query#ref

Commonly used protocols are HTTP, HTTPS, FTP, and File. The host is called the authority. Ports are channels from where data packets are sent and received. If a port is not mentioned, the default PORT 80 is used in the case of HTTP.

Constructors

All methods used to work with URLs can be found in the java.net.URL class. The constructors are as follows:

• public URL (String protocol, String host, int port, String file) throws MalformedURLException
• public URL (String protocol, String host, String file) throws MalformedURLException
• public URL (String url) throws MalformedURLException
• public URL (URL context, String url) throws MalformedURLException

Methods

Example

This example will put to use some of the methods mentioned above on a working URL.

import java.net.*;
import java.io.*;
public class SampleURL {
public static void main (String [] args)
{
try {
URL url = mew URL (“https://www.wikipedia.org/”);
System.out.println("URL is " + url.toString());
System.out.println("protocol is " + url.getProtocol());
System.out.println("authority is " + url.getAuthority());
System.out.println("file name is " + url.getFile());
System.out.println("host is " + url.getHost());
System.out.println("path is " + url.getPath());
System.out.println("port is " + url.getPort());
System.out.println("default port is " + url.getDefaultPort());
System.out.println("query is " + url.getQuery());
System.out.println("ref is " + url.getRef());
}
catch (IO Exception e) {
e.printStackTrace();
}
}
}