org.htmlparser.beans

Class StringBean

Implemented Interfaces:
Serializable

public class StringBean
extends NodeVisitor
implements Serializable

Extract strings from a URL.

Text within <SCRIPT></SCRIPT> tags is removed.

The text within <PRE></PRE> tags is not altered.

The property Strings, which is the output property is null until a URL is set. So a typical usage is:

     StringBean sb = new StringBean ();
     sb.setLinks (false);
     sb.setReplaceNonBreakingSpaces (true);
     sb.setCollapse (true);
     sb.setURL ("http://www.netbeans.org"); // the HTTP is performed here
     String s = sb.getStrings ();
 
You can also use the StringBean as a NodeVisitor on your own parser, in which case you have to refetch your page if you change one of the properties because it resets the Strings property:
     StringBean sb = new StringBean ();
     Parser parser = new Parser ("http://cbc.ca");
     parser.visitAllNodesWith (sb);
     String s = sb.getStrings ();
     sb.setLinks (true);
     parser.reset ();
     parser.visitAllNodesWith (sb);
     String sl = sb.getStrings ();
 
According to Nick Burch, who contributed the patch, this is handy if you don't want StringBean to wander off and get the content itself, either because you already have it, it's not on a website etc.

Field Summary

static String
PROP_COLLAPSE_PROPERTY
Property name in event where the 'collapse whitespace' state changes.
static String
PROP_CONNECTION_PROPERTY
Property name in event where the connection changes.
static String
PROP_LINKS_PROPERTY
Property name in event where the 'embed links' state changes.
static String
PROP_REPLACE_SPACE_PROPERTY
Property name in event where the 'replace non-breaking spaces' state changes.
static String
PROP_STRINGS_PROPERTY
Property name in event where the URL contents changes.
static String
PROP_URL_PROPERTY
Property name in event where the URL changes.
protected StringBuffer
mBuffer
The buffer text is stored in while traversing the HTML.
protected boolean
mCollapse
If true sequences of whitespace characters are replaced with a single space character.
protected int
mCollapseState
The state of the collapse processiung state machine.
protected boolean
mIsPre
Set true when traversing a PRE tag.
protected boolean
mIsScript
Set true when traversing a SCRIPT tag.
protected boolean
mIsStyle
Set true when traversing a STYLE tag.
protected boolean
mLinks
If true the link URLs are embedded in the text output.
protected Parser
mParser
The parser used to extract strings.
protected PropertyChangeSupport
mPropertySupport
Bound property support.
protected boolean
mReplaceSpace
If true regular space characters are substituted for non-breaking spaces in the text output.
protected String
mStrings
The strings extracted from the URL.

Constructor Summary

StringBean()
Create a StringBean object.

Method Summary

void
addPropertyChangeListener(PropertyChangeListener listener)
Add a PropertyChangeListener to the listener list.
protected void
carriageReturn()
Appends a newline to the buffer if there isn't one there already.
protected void
collapse(StringBuffer buffer, String string)
Add the given text collapsing whitespace.
protected String
extractStrings()
Extract the text from a page.
boolean
getCollapse()
Get the current 'collapse whitespace' state.
URLConnection
getConnection()
Get the current connection.
boolean
getLinks()
Get the current 'include links' state.
boolean
getReplaceNonBreakingSpaces()
Get the current 'replace non breaking spaces' state.
String
getStrings()
Return the textual contents of the URL.
String
getURL()
Get the current URL.
static void
main(String[] args)
Unit test.
void
removePropertyChangeListener(PropertyChangeListener listener)
Remove a PropertyChangeListener from the listener list.
void
setCollapse(boolean collapse)
Set the current 'collapse whitespace' state.
void
setConnection(URLConnection connection)
Set the parser's connection.
void
setLinks(boolean links)
Set the 'include links' state.
void
setReplaceNonBreakingSpaces(boolean replace)
Set the 'replace non breaking spaces' state.
protected void
setStrings()
Fetch the URL contents.
void
setURL(String url)
Set the URL to extract strings from.
protected void
updateStrings(String strings)
Assign the Strings property, firing the property change.
void
visitEndTag(Tag tag)
Resets the state of the PRE and SCRIPT flags.
void
visitStringNode(Text string)
Appends the text to the output.
void
visitTag(Tag tag)
Appends a NEWLINE to the output if the tag breaks flow, and possibly sets the state of the PRE and SCRIPT flags.

Methods inherited from class org.htmlparser.visitors.NodeVisitor

beginParsing, finishedParsing, shouldRecurseChildren, shouldRecurseSelf, visitEndTag, visitRemarkNode, visitStringNode, visitTag

Field Details

PROP_COLLAPSE_PROPERTY

public static final String PROP_COLLAPSE_PROPERTY
Property name in event where the 'collapse whitespace' state changes.

PROP_CONNECTION_PROPERTY

public static final String PROP_CONNECTION_PROPERTY
Property name in event where the connection changes.

PROP_LINKS_PROPERTY

public static final String PROP_LINKS_PROPERTY
Property name in event where the 'embed links' state changes.

PROP_REPLACE_SPACE_PROPERTY

public static final String PROP_REPLACE_SPACE_PROPERTY
Property name in event where the 'replace non-breaking spaces' state changes.

PROP_STRINGS_PROPERTY

public static final String PROP_STRINGS_PROPERTY
Property name in event where the URL contents changes.

PROP_URL_PROPERTY

public static final String PROP_URL_PROPERTY
Property name in event where the URL changes.

mBuffer

protected StringBuffer mBuffer
The buffer text is stored in while traversing the HTML.

mCollapse

protected boolean mCollapse
If true sequences of whitespace characters are replaced with a single space character.

mCollapseState

protected int mCollapseState
The state of the collapse processiung state machine.

mIsPre

protected boolean mIsPre
Set true when traversing a PRE tag.

mIsScript

protected boolean mIsScript
Set true when traversing a SCRIPT tag.

mIsStyle

protected boolean mIsStyle
Set true when traversing a STYLE tag.

mLinks

protected boolean mLinks
If true the link URLs are embedded in the text output.

mParser

protected Parser mParser
The parser used to extract strings.

mPropertySupport

protected PropertyChangeSupport mPropertySupport
Bound property support.

mReplaceSpace

protected boolean mReplaceSpace
If true regular space characters are substituted for non-breaking spaces in the text output.

mStrings

protected String mStrings
The strings extracted from the URL.

Constructor Details

StringBean

public StringBean()
Create a StringBean object. Default property values are set to 'do the right thing':

Links is set false so text appears like a browser would display it, albeit without the colour or underline clues normally associated with a link.

ReplaceNonBreakingSpaces is set true, so that printing the text works, but the extra information regarding these formatting marks is available if you set it false.

Collapse is set true, so text appears compact like a browser would display it.

Method Details

addPropertyChangeListener

public void addPropertyChangeListener(PropertyChangeListener listener)
Add a PropertyChangeListener to the listener list. The listener is registered for all properties.
Parameters:
listener - The PropertyChangeListener to be added.

carriageReturn

protected void carriageReturn()
Appends a newline to the buffer if there isn't one there already. Except if the buffer is empty.

collapse

protected void collapse(StringBuffer buffer,
                        String string)
Add the given text collapsing whitespace. Use a little finite state machine:
 state 0: whitepace was last emitted character
 state 1: in whitespace
 state 2: in word
 A whitespace character moves us to state 1 and any other character
 moves us to state 2, except that state 0 stays in state 0 until
 a non-whitespace and going from whitespace to word we emit a space
 before the character:
    input:     whitespace   other-character
 state\next
    0               0             2
    1               1        space then 2
    2               1             2
 
Parameters:
buffer - The buffer to append to.
string - The string to append.

extractStrings

protected String extractStrings()
            throws ParserException
Extract the text from a page.
Returns:
The textual contents of the page.
Throws:
ParserException - If a parse error occurs.

getCollapse

public boolean getCollapse()
Returns:
true if sequences of whitespace (space '\u0020', tab '\u0009', form feed '\u000C', zero-width space '\u200B', carriage-return '\r' and NEWLINE '\n') are to be replaced with a single space.

getConnection

public URLConnection getConnection()
Get the current connection.
Returns:
The connection that the parser has or null if it hasn't been set or the parser hasn't been constructed yet.

getLinks

public boolean getLinks()
Get the current 'include links' state.
Returns:
true if link text is included in the text extracted from the URL, false otherwise.

getReplaceNonBreakingSpaces

public boolean getReplaceNonBreakingSpaces()
Get the current 'replace non breaking spaces' state.
Returns:
true if non-breaking spaces (character '\u00a0', numeric character reference &#160; or character entity reference &nbsp;) are to be replaced with normal spaces (character '\u0020').

getStrings

public String getStrings()
Return the textual contents of the URL. This is the primary output of the bean.
Returns:
The user visible (what would be seen in a browser) text.

getURL

public String getURL()
Get the current URL.
Returns:
The URL from which text has been extracted, or null if this property has not been set yet.

main

public static void main(String[] args)
Unit test.
Parameters:
args - Pass arg[0] as the URL to process.

removePropertyChangeListener

public void removePropertyChangeListener(PropertyChangeListener listener)
Remove a PropertyChangeListener from the listener list. This removes a registered PropertyChangeListener.
Parameters:
listener - The PropertyChangeListener to be removed.

setCollapse

public void setCollapse(boolean collapse)
Set the current 'collapse whitespace' state. If the setting is changed after the URL has been set, the text from the URL will be reacquired, which is possibly expensive. The internal state of the collapse state machine can be reset with code like this: setCollapse (getCollapse ());
Parameters:
collapse - If true, sequences of whitespace will be reduced to a single space.

setConnection

public void setConnection(URLConnection connection)
Set the parser's connection. The text from the URL will be fetched, which may be expensive, so this property should be set last.
Parameters:
connection - New value of property Connection.

setLinks

public void setLinks(boolean links)
Set the 'include links' state. If the setting is changed after the URL has been set, the text from the URL will be reacquired, which is possibly expensive.
Parameters:
links - Use true if link text is to be included in the text extracted from the URL, false otherwise.

setReplaceNonBreakingSpaces

public void setReplaceNonBreakingSpaces(boolean replace)
Set the 'replace non breaking spaces' state. If the setting is changed after the URL has been set, the text from the URL will be reacquired, which is possibly expensive.
Parameters:
replace - true if non-breaking spaces (character '\u00a0', numeric character reference &#160; or character entity reference &nbsp;) are to be replaced with normal spaces (character '\u0020').

setStrings

protected void setStrings()
Fetch the URL contents. Only do work if there is a valid parser with it's URL set.

setURL

public void setURL(String url)
Set the URL to extract strings from. The text from the URL will be fetched, which may be expensive, so this property should be set last.
Parameters:
url - The URL that text should be fetched from.

updateStrings

protected void updateStrings(String strings)
Assign the Strings property, firing the property change.
Parameters:
strings - The new value of the Strings property.

visitEndTag

public void visitEndTag(Tag tag)
Resets the state of the PRE and SCRIPT flags.
Overrides:
visitEndTag in interface NodeVisitor
Parameters:
tag - The end tag to process.

visitStringNode

public void visitStringNode(Text string)
Appends the text to the output.
Overrides:
visitStringNode in interface NodeVisitor
Parameters:
string - The text node.

visitTag

public void visitTag(Tag tag)
Appends a NEWLINE to the output if the tag breaks flow, and possibly sets the state of the PRE and SCRIPT flags.
Overrides:
visitTag in interface NodeVisitor
Parameters:
tag - The tag to examine.

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