The URL class is the gateway to any of the resource available on 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
What is a URL?
As many of you must be knowing that Uniform Resource Locator-URL is a string of text that identifies all the resources on 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 three-components system-
- Protocol: HTTP is the protocol here
- Hostname: Name of the machine on which the resource lives.
- File Name: The path name to the file on the machine.
- Port Number: Port number to which to connect (typically optional).
Some constructors for URL class:-
- URL(String address) throws MalformedURLException: It creates a URL object from the specified String.
- URL(String protocol, String host, String file): Creates a URL object from the specified protcol, host, and file name.
- URL(String protocol, String host, int port, String file): Creates a URL object from protocol, host, port and file name.
- URL(URL context, String spec): Creates a URL object by parsing the given spec in the given context.
- 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. - URL(URL context, String spec, URLStreamHandler handler):-
Creates a URL by parsing the given spec with the specified handler within a specified context.
Sample Program:
// Java program to demonstrate working of URL import java.net.MalformedURLException; import java.net.URL; public class URLclass1 { public static void main(String[] args) throws MalformedURLException { // creates a URL with string representation. URL url1 = "WK26I4fT8gfth6CACg#q=geeks+for+geeks+java" ); // creates a URL with a protocol,hostname,and path URL url2 = new URL( "http" , "www.geeksforgeeks.org" , "/jvm-works-jvm-architecture/" ); "q=gnu&rlz=1C1CHZL_enIN71" + "4IN715&oq=gnu&aqs=chrome..69i57j6" + "9i60l5.653j0j7&sourceid=chrome&ie=UTF" + "-8#q=geeks+for+geeks+java" ); // print 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-" ); // retrieve the protocol for the URL System.out.println( "Protocol:- " + url3.getProtocol()); // retrieve the hostname of the url System.out.println( "Hostname:- " + url3.getHost()); // retrieve the defalut port System.out.println( "Default port:- " + url3.getDefaultPort()); // retrieve the query part of URL System.out.println( "Query:- " + url3.getQuery()); // retrive the path of URL System.out.println( "Path:- " + url3.getPath()); // retrive the file name System.out.println( "File:- " + url3.getFile()); // retrieve 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://tutorialspoint.dev/slugresolver/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
Explanation of some methods used in above program are as follows:-
- public String toString(): As in any class, toString() returns the string representation of the given URL object.
- public String getAuthority(): returns the authority part of URL or null if empty.
- public String getPath(): returns the path of the URL, or null if empty.
- public String getQuery(): returns the query part of URL. Query is the the part after the ‘?’ in the URL. Whenever logic is used to display the result, there would be a query field in URL. It is similar to querying a database.
- public String getHost(): return the hostname of the URL in IPv6 format.
- public String getFile(): returns the file name.
- public String 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 exaple by querying anything on google and seeing the part after ‘#’.
- public int getPort(): returns the port associated with the protocol specified by the URL.
- public int getDefaultPort: returns the default port used.
- public String getProtocol(): returns the protocol used by the URL.
References
http://docs.oracle.com/javase/7/docs/api/java/net/URL.html#getAuthority()
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