Package org.apache.nutch.util

Class URLUtil

java.lang.Object

org.apache.nutch.util.URLUtil

public class URLUtil
extends Object

Utility class for URL analysis

Constructor Summary

Constructors

Constructor	Description
URLUtil()

Method Summary

Modifier and Type	Method	Description
static String	chooseRepr(String src, String dst, boolean temp)	Given two urls, a src and a destination of a redirect, it returns the representative url.
static String	getDomainName(String url)	Returns the domain name of the URL.
static String	getDomainName(URL url)	Get the domain name of the URL.
static String	getDomainSuffix(String url)	Returns the domain suffix corresponding to the last public part of the hostname.
static String	getDomainSuffix(URL url)	Returns the public suffix corresponding to the last public part of the hostname.
static String	getHost(String url)	Returns the lowercased hostname for the URL or null if the URL is not well-formed.
static String	getHost(URL url)	Returns the lowercased hostname for the URL.
static String[]	getHostSegments(String url)	Partitions of the hostname of the url by "."
static String[]	getHostSegments(URL url)	Partitions of the hostname of the url by "."
static String	getPage(String url)	Returns the page for the url.
static String	getProtocol(String url)
static String	getProtocol(URL url)
static String	getTopLevelDomainName(String url)	Returns the top-level domain name of the URL.
static String	getTopLevelDomainName(URL url)	Returns the top-level domain name of the URL.
static boolean	isHomePageOf(URL url, String hostName)	Test whether a URL is the home page or root page of a host.
static boolean	isSameDomainName(String url1, String url2)	Returns whether the given URLs have the same domain name.
static boolean	isSameDomainName(URL url1, URL url2)	Returns whether the given URLs have the same domain name.
static void	main(String[] args)	For testing
static URL	resolveURL(URL base, String target)	Resolve relative URL-s and fix a java.net.URL error in handling of URLs with pure query targets.
static String	toASCII(String url)
static String	toUNICODE(String url)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

URLUtil

public URLUtil()

Method Detail

resolveURL

public static URL resolveURL(URL base,
                             String target)
                      throws MalformedURLException

Resolve relative URL-s and fix a java.net.URL error in handling of URLs with pure query targets.

Parameters:

base - base url

target - target url (may be relative)

Returns:

resolved absolute url.

Throws:

MalformedURLException - if the input base URL is malformed

getDomainName

public static String getDomainName(URL url)

Get the domain name of the URL. The domain name of a URL is the substring of the URL's hostname, w/o subdomain names. As an example
getDomainName(new URL("https://lucene.apache.org/"))
will return
apache.org Special cases:

• if the hostname does not end in a valid domain suffix, the entire hostname is returned.
• for URLs without a hostname, an empty string is returned.

Valid domain suffixes are taken from the https://publicsuffix.org/list/public_suffix_list.dat and are compared using crawler-commons' EffectiveTldFinder. Only ICANN domain suffixes are used. Because EffectiveTldFinder loads the public suffix list as file "effective_tld_names.dat" from the Java classpath, it's possible to use the a specific version of the public suffix list (e.g., the most recent one) by placing the public suffix list with the name "effective_tld_names.dat" in Nutch's conf/ folder. See EffectiveTldFinder.getAssignedDomain(String, boolean, boolean)

Parameters:

url - input URL to extract the domain from

Returns:

the domain name string

getDomainName

public static String getDomainName(String url)
                            throws MalformedURLException

Returns the domain name of the URL. The domain name of a URL is the substring of the URL's hostname, w/o subdomain names. As an example
getDomainName("https://lucene.apache.org/")
will return
apache.org See getDomainName(URL) for more information.

Parameters:

url - input URL string to extract the domain from

Returns:

the domain name

Throws:

MalformedURLException - if the input URL is malformed

getTopLevelDomainName

public static String getTopLevelDomainName(URL url)

Returns the top-level domain name of the URL. The top-level domain name of a URL is the substring of the URL's hostname, w/o subdomain names. As an example
getTopLevelDomainName(new URL("https://www.example.co.uk/"))
will return
uk In case of internationalized top-level domains, the ASCII representation is returned.

Parameters:

url - input URL to extract the top-level domain name from

Returns:

the top-level domain name or null if there is none

getTopLevelDomainName

public static String getTopLevelDomainName(String url)
                                    throws MalformedURLException

Returns the top-level domain name of the URL. The top-level domain name of a URL is the substring of the URL's hostname, w/o subdomain names. As an example
getTopLevelDomainName("https://www.example.co.uk/")
will return
uk In case of internationalized top-level domains, the ASCII representation is returned.

Parameters:

url - input URL string to extract the top-level domain name from

Returns:

the top-level domain name or null if there is none

Throws:

MalformedURLException - if the input URL is malformed

isSameDomainName

public static boolean isSameDomainName(URL url1,
                                       URL url2)

Returns whether the given URLs have the same domain name. As an example,
isSameDomain(new URL("http://lucene.apache.org") , new URL("http://people.apache.org/"))
will return true.

Parameters:

url1 - first URL to compare domain name

url2 - second URL to compare domain name

Returns:

true if the domain names are equal

isSameDomainName

public static boolean isSameDomainName(String url1,
                                       String url2)
                                throws MalformedURLException

Returns whether the given URLs have the same domain name. As an example,
isSameDomain("http://lucene.apache.org" ,"http://people.apache.org/")
will return true.

Parameters:

url1 - first URL string to compare domain name

url2 - second URL string to compare domain name

Returns:

true if the domain names are equal

Throws:

MalformedURLException - if any of the input URLs are malformed

getDomainSuffix

public static String getDomainSuffix(URL url)

Returns the public suffix corresponding to the last public part of the hostname. In case of internationalized domain suffixes, the ASCII representation is returned. For the URL https://www.taiuru.māori.nz/ the suffix xn--mori-qsa.nz is returned.

Parameters:

url - a URL to extract the domain suffix from

Returns:

the domain suffix or null if there is none

getDomainSuffix

public static String getDomainSuffix(String url)
                              throws MalformedURLException

Returns the domain suffix corresponding to the last public part of the hostname. In case of internationalized domain suffixes, the ASCII representation is returned. For the URL https://www.taiuru.māori.nz/ the suffix xn--mori-qsa.nz is returned.

Parameters:

url - a URL to extract the domain suffix from

Returns:

the domain suffix or null if there is none

Throws:

MalformedURLException - if the input URL string is malformed

getHostSegments

public static String[] getHostSegments(URL url)

Partitions of the hostname of the url by "."

Parameters:

url - a URL to extract host segments from

Returns:

a string array of host segments

getHostSegments

public static String[] getHostSegments(String url)
                                throws MalformedURLException

Partitions of the hostname of the url by "."

Parameters:

url - a url string to extract host segments from

Returns:

a string array of host segments

Throws:

MalformedURLException - if the input url string is malformed

chooseRepr

public static String chooseRepr(String src,
                                String dst,
                                boolean temp)

Given two urls, a src and a destination of a redirect, it returns the representative url.

This method implements an extended version of the algorithm used by the Yahoo! Slurp crawler described here:
How does the Yahoo! webcrawler handle redirects?

• Choose target url if either url is malformed.
• If different domains the keep the destination whether or not the redirect is temp or perm
• a.com -> b.com*
• If the redirect is permanent and the source is root, keep the source.
• *a.com -> a.com?y=1 || *a.com -> a.com/xyz/index.html
• If the redirect is permanent and the source is not root and the destination is root, keep the destination
• a.com/xyz/index.html -> a.com*
• If the redirect is permanent and neither the source nor the destination is root, then keep the destination
• a.com/xyz/index.html -> a.com/abc/page.html*
• If the redirect is temporary and source is root and destination is not root, then keep the source
• *a.com -> a.com/xyz/index.html
• If the redirect is temporary and source is not root and destination is root, then keep the destination
• a.com/xyz/index.html -> a.com*
• If the redirect is temporary and neither the source or the destination is root, then keep the shortest url. First check for the shortest host, and if both are equal then check by path. Path is first by length then by the number of / path separators.
• a.com/xyz/index.html -> a.com/abc/page.html*
• *www.a.com/xyz/index.html -> www.news.a.com/xyz/index.html
• If the redirect is temporary and both the source and the destination are root, then keep the shortest sub-domain
• *www.a.com -> www.news.a.com

While not in this logic there is a further piece of representative url logic that occurs during indexing and after scoring. During creation of the basic fields before indexing, if a url has a representative url stored we check both the url and its representative url (which should never be the same) against their linkrank scores and the highest scoring one is kept as the url and the lower scoring one is held as the orig url inside of the index.

Parameters:

src - The source url.

dst - The destination url.

temp - Is the redirect a temporary redirect.

Returns:

String The representative url.

getHost

public static String getHost(String url)

Returns the lowercased hostname for the URL or null if the URL is not well-formed.

Parameters:

url - The URL to check.

Returns:

String the hostname for the URL.

getHost

public static String getHost(URL url)

Returns the lowercased hostname for the URL.

Parameters:

url - The URL to check.

Returns:

String the hostname for the URL.

getPage

public static String getPage(String url)

Returns the page for the url. The page consists of the protocol, host, and path, but does not include the query string. The host is lowercased but the path is not.

Parameters:

url - The url to check.

Returns:

String The page for the url.

getProtocol

public static String getProtocol(String url)

getProtocol

public static String getProtocol(URL url)

toASCII

public static String toASCII(String url)

toUNICODE

public static String toUNICODE(String url)

main

public static void main(String[] args)

For testing

Parameters:

args - print with no args to get help

isHomePageOf

public static boolean isHomePageOf(URL url,
                                   String hostName)

Test whether a URL is the home page or root page of a host. This is the case if the URL path is / and query, port, fragment, userinfo are empty resp. not given. In other words the URL is: protocol://hostName/

Parameters:

url - the URL to test

hostName - the host name to test the URL on

Returns:

true if the URL is the home or root page of the host