URL Class in Java with Examples

URL known as Uniform Resource Locator is simply a string of text that identifies all the resources on the Internet, telling us the address of the resource, how to communicate with it, and retrieve something from it.

Components of a URL

A URL can have many forms. The most general however follows a three-components system as proposed below:

1. Protocol: HTTP is the protocol here
2. Hostname: Name of the machine on which the resource lives.
3. File Name: The pathname to the file on the machine.
4. Port Number: Port number to which to connect (typically optional).

URL Class 

The URL class is the gateway to any of the resources available on the internet. A Class URL represents a Uniform Resource Locator, which is a pointer to a “resource” on the World Wide Web. A resource can point to a simple file or directory, or it can refer to a more complicated object, such as a query to a database or to a search engine.

Constructors of the URL class

1. URL(String address) throws MalformedURLException: It creates a URL object from the specified String.
2. URL(String protocol, String host, String file): Creates a URL object from the specified protocol, host, and file name.
3. URL(String protocol, String host, int port, String file): Creates a URL object from protocol, host, port, and file name.
4. URL(URL context, String spec): Creates a URL object by parsing the given spec in the given context. 
5. URL(String protocol, String host, int port, String file, URLStreamHandler handler):
   Creates a URL object from the specified protocol, host, port number, file, and handler.
6. URL(URL context, String spec, URLStreamHandler handler):
   Creates a URL by parsing the given spec with the specified handler within a specified context.

Important Methods used in URL class

Method	Action Performed
getAuthority()	Returns the authority part of URL or null if empty
getDefaultPort()	Returns the default port used
getFile()	Returns the file name.
getHost()	Return the hostname of the URL in IPv6 format
getPath()	Returns the path of the URL, or null if empty
getPort()	Returns the port associated with the protocol specified by the URL
getProtocol()	Returns the protocol used by the URL
getQuery()	the Returns the query part of URL. A query is a part after the ‘?’ in the URL. Whenever logic is used to display the result, there would be a query field in the URL. It is similar to querying a database.
getRef()	Returns the reference of the URL object. Usually, the reference is the part marked by a ‘#’ in the URL. You can see the working example by querying anything on Google and seeing the part after ‘#’
toString()	As in any class, toString() returns the string representation of the given URL object.

Example:

Java

// Java program to demonstrate working of URL

// Importing required classes
import java.net.MalformedURLException;
import java.net.URL;

// Main class
// URL class
public class GFG {

    // Main driver method
    public static void main(String[] args)
        throws MalformedURLException
    {

        // Creating a URL with string representation
        URL url1 = new URL(
            "https://www.google.co.in/?gfe_rd=cr&ei=ptYq"
            + "WK26I4fT8gfth6CACg#q=geeks+for+geeks+java");

        // Creating a URL with a protocol,hostname,and path
        URL url2 = new URL("http", "www.geeksforgeeks.org",
                           "/jvm-works-jvm-architecture/");

        URL url3 = new URL(
            "https://www.google.co.in/search?"
            + "q=gnu&rlz=1C1CHZL_enIN71"
            + "4IN715&oq=gnu&aqs=chrome..69i57j6"
            + "9i60l5.653j0j7&sourceid=chrome&ie=UTF"
            + "-8#q=geeks+for+geeks+java");

        // Printing the string representation of the URL
        System.out.println(url1.toString());
        System.out.println(url2.toString());
        System.out.println();
        System.out.println(
            "Different components of the URL3-");

        // Retrieving the protocol for the URL
        System.out.println("Protocol:- "
                           + url3.getProtocol());

        // Retrieving the hostname of the url
        System.out.println("Hostname:- " + url3.getHost());

        // Retrieving the default port
        System.out.println("Default port:- "
                           + url3.getDefaultPort());

        // Retrieving the query part of URL
        System.out.println("Query:- " + url3.getQuery());

        // Retrieving the path of URL
        System.out.println("Path:- " + url3.getPath());

        // Retrieving the file name
        System.out.println("File:- " + url3.getFile());

        // Retrieving the reference
        System.out.println("Reference:- " + url3.getRef());
    }
}

Output:  

https://www.google.co.in/?gfe_rd=cr&ei=ptYqWK26I4fT8gfth6CACg#q=geeks+for+geeks+java
https://www.geeksforgeeks.org/jvm-works-jvm-architecture/

Different components of the URL3-
Protocol:- https
Hostname:- www.google.co.in
Default port:- 443
Query:- q=gnu&rlz=1C1CHZL_enIN714IN715&oq=gnu&aqs=chrome..69i57j69i60l5.653j0j7&sourceid=chrome&ie=UTF-8
Path:- /search
File:- /search?q=gnu&rlz=1C1CHZL_enIN714IN715&oq=gnu&aqs=chrome..69i57j69i60l5.653j0j7&sourceid=chrome&ie=UTF-8
Reference:- q=geeks+for+geeks+java

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