org.htmlparser.filters

Class RegexFilter

Implemented Interfaces:
Cloneable, NodeFilter, Serializable

public class RegexFilter
extends Object
implements NodeFilter

This filter accepts all string nodes matching a regular expression. Because this searches Text nodes. it is only useful for finding small fragments of text, where it is unlikely to be broken up by a tag. To find large fragments of text you should convert the page to plain text with something like the StringBean and then apply the regular expression.

For example, to look for dates use:

   (19|20)\d\d([- \\/.](0[1-9]|1[012])[- \\/.](0[1-9]|[12][0-9]|3[01]))?
 
as in:
 Parser parser = new Parser ("http://cbc.ca");
 RegexFilter filter = new RegexFilter ("(19|20)\\d\\d([- \\\\/.](0[1-9]|1[012])[- \\\\/.](0[1-9]|[12][0-9]|3[01]))?");
 NodeIterator iterator = parser.extractAllNodesThatMatch (filter).elements ();
 
which matches a date in yyyy-mm-dd format between 1900-01-01 and 2099-12-31, with a choice of five separators, either a dash, a space, either kind of slash or a period. The year is matched by (19|20)\d\d which uses alternation to allow the either 19 or 20 as the first two digits. The round brackets are mandatory. The month is matched by 0[1-9]|1[012], again enclosed by round brackets to keep the two options together. By using character classes, the first option matches a number between 01 and 09, and the second matches 10, 11 or 12. The last part of the regex consists of three options. The first matches the numbers 01 through 09, the second 10 through 29, and the third matches 30 or 31. The day and month are optional, but must occur together because of the ()? bracketing after the year.

Field Summary

static int
FIND
Use find() match strategy.
static int
LOOKINGAT
Use lookingAt() match strategy.
static int
MATCH
Use match() matching strategy.
protected Pattern
mPattern
The compiled regular expression to search for.
protected String
mPatternString
The regular expression to search for.
protected int
mStrategy
The match strategy.

Constructor Summary

RegexFilter()
Creates a new instance of RegexFilter that accepts string nodes matching the regular expression ".*" using the FIND strategy.
RegexFilter(String pattern)
Creates a new instance of RegexFilter that accepts string nodes matching a regular expression using the FIND strategy.
RegexFilter(String pattern, int strategy)
Creates a new instance of RegexFilter that accepts string nodes matching a regular expression.

Method Summary

boolean
accept(Node node)
Accept string nodes that match the regular expression.
String
getPattern()
Get the search pattern.
int
getStrategy()
Get the search strategy.
void
setPattern(String pattern)
Set the search pattern.
void
setStrategy(int strategy)
Set the search pattern.

Field Details

FIND

public static final int FIND
Use find() match strategy.
Field Value:
3

LOOKINGAT

public static final int LOOKINGAT
Use lookingAt() match strategy.
Field Value:
2

MATCH

public static final int MATCH
Use match() matching strategy.
Field Value:
1

mPattern

protected Pattern mPattern
The compiled regular expression to search for.

mPatternString

protected String mPatternString
The regular expression to search for.

mStrategy

protected int mStrategy
The match strategy.

Constructor Details

RegexFilter

public RegexFilter()
Creates a new instance of RegexFilter that accepts string nodes matching the regular expression ".*" using the FIND strategy.

RegexFilter

public RegexFilter(String pattern)
Creates a new instance of RegexFilter that accepts string nodes matching a regular expression using the FIND strategy.
Parameters:
pattern - The pattern to search for.

RegexFilter

public RegexFilter(String pattern,
                   int strategy)
Creates a new instance of RegexFilter that accepts string nodes matching a regular expression.
Parameters:
pattern - The pattern to search for.
strategy - The type of match:
  1. MATCH use matches() method: attempts to match the entire input sequence against the pattern
  2. LOOKINGAT use lookingAt() method: attempts to match the input sequence, starting at the beginning, against the pattern
  3. FIND use find() method: scans the input sequence looking for the next subsequence that matches the pattern

Method Details

accept

public boolean accept(Node node)
Accept string nodes that match the regular expression.
Specified by:
accept in interface NodeFilter
Parameters:
node - The node to check.
Returns:
true if the regular expression matches the text of the node, false otherwise.

getPattern

public String getPattern()
Get the search pattern.
Returns:
Returns the pattern.

getStrategy

public int getStrategy()
Get the search strategy.
Returns:
Returns the strategy.

setPattern

public void setPattern(String pattern)
Set the search pattern.
Parameters:
pattern - The pattern to set.

setStrategy

public void setStrategy(int strategy)
Set the search pattern.
Parameters:
strategy - The strategy to use. One of MATCH, LOOKINGAT or FIND.

HTML Parser is an open source library released under LGPL. SourceForge.net