ElementRemover (NekoHTML 1.9.21 Implementation)

java.lang.Object
- org.cyberneko.html.filters.DefaultFilter
- - org.cyberneko.html.filters.ElementRemover

All Implemented Interfaces:

HTMLComponent
```
public class ElementRemover
extends DefaultFilter
```
This class is a document filter capable of removing specified elements from the processing stream. There are two options for processing document elements:
- specifying those elements which should be accepted and, optionally, which attributes of that element should be kept; and
- specifying those elements whose tags and content should be completely removed from the event stream.
The first option allows the application to specify which elements appearing in the event stream should be accepted and, therefore, passed on to the next stage in the pipeline. All elements not in the list of acceptable elements have their start and end tags stripped from the event stream unless those elements appear in the list of elements to be removed.
The second option allows the application to specify which elements should be completely removed from the event stream. When an element appears that is to be removed, the element's start and end tag as well as all of that element's content is removed from the event stream.
A common use of this filter would be to only allow rich-text and linking elements as well as the character content to pass through the filter — all other elements would be stripped. The following code shows how to configure this filter to perform this task:
```
  ElementRemover remover = new ElementRemover();
  remover.acceptElement("b", null);
  remover.acceptElement("i", null);
  remover.acceptElement("u", null);
  remover.acceptElement("a", new String[] { "href" });
 
```
However, this would still allow the text content of other elements to pass through, which may not be desirable. In order to further "clean" the input, the removeElement option can be used. The following piece of code adds the ability to completely remove any <SCRIPT> tags and content from the stream.
```
  remover.removeElement("script");
 
```
Note: All text and accepted element children of a stripped element is retained. To completely remove an element's content, use the removeElement method.
Note: Care should be taken when using this filter because the output may not be a well-balanced tree. Specifically, if the application removes the <HTML> element (with or without retaining its children), the resulting document event stream will no longer be well-formed.
Version:

$Id: ElementRemover.java,v 1.5 2005/02/14 03:56:54 andyc Exp $

Author:

Andy Clark

Field Summary

Fields
Modifier and Type	Field and Description
`protected java.util.Hashtable`	`fAcceptedElements` Accepted elements.
`protected int`	`fElementDepth` The element depth.
`protected int`	`fRemovalElementDepth` The element depth at element removal.
`protected java.util.Hashtable`	`fRemovedElements` Removed elements.
`protected static java.lang.Object`	`NULL` A "null" object.

Fields inherited from class org.cyberneko.html.filters.DefaultFilter
fDocumentHandler, fDocumentSource

Constructor Summary

Constructors
Constructor and Description

ElementRemover()

Constructors
Constructor and Description
`ElementRemover()`

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`acceptElement(java.lang.String element, java.lang.String[] attributes)` Specifies that the given element should be accepted and, optionally, which attributes of that element should be kept.
`void`	`characters(XMLString text, Augmentations augs)` Characters.
`void`	`comment(XMLString text, Augmentations augs)` Comment.
`protected boolean`	`elementAccepted(java.lang.String element)` Returns true if the specified element is accepted.
`protected boolean`	`elementRemoved(java.lang.String element)` Returns true if the specified element should be removed.
`void`	`emptyElement(QName element, XMLAttributes attributes, Augmentations augs)` Empty element.
`void`	`endCDATA(Augmentations augs)` End CDATA section.
`void`	`endElement(QName element, Augmentations augs)` End element.
`void`	`endGeneralEntity(java.lang.String name, Augmentations augs)` End general entity.
`void`	`endPrefixMapping(java.lang.String prefix, Augmentations augs)` End prefix mapping.
`protected boolean`	`handleOpenTag(QName element, XMLAttributes attributes)` Handles an open tag.
`void`	`ignorableWhitespace(XMLString text, Augmentations augs)` Ignorable whitespace.
`void`	`processingInstruction(java.lang.String target, XMLString data, Augmentations augs)` Processing instruction.
`void`	`removeElement(java.lang.String element)` Specifies that the given element should be completely removed.
`void`	`startCDATA(Augmentations augs)` Start CDATA section.
`void`	`startDocument(XMLLocator locator, java.lang.String encoding, Augmentations augs)` Start document.
`void`	`startDocument(XMLLocator locator, java.lang.String encoding, NamespaceContext nscontext, Augmentations augs)` Start document.
`void`	`startElement(QName element, XMLAttributes attributes, Augmentations augs)` Start element.
`void`	`startGeneralEntity(java.lang.String name, XMLResourceIdentifier id, java.lang.String encoding, Augmentations augs)` Start general entity.
`void`	`startPrefixMapping(java.lang.String prefix, java.lang.String uri, Augmentations augs)` Start prefix mapping.
`void`	`textDecl(java.lang.String version, java.lang.String encoding, Augmentations augs)` Text declaration.

Methods inherited from class org.cyberneko.html.filters.DefaultFilter
doctypeDecl, endDocument, getDocumentHandler, getDocumentSource, getFeatureDefault, getPropertyDefault, getRecognizedFeatures, getRecognizedProperties, merge, reset, setDocumentHandler, setDocumentSource, setFeature, setProperty, xmlDecl

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NULL

protected static final java.lang.Object NULL

A "null" object.

fAcceptedElements

protected java.util.Hashtable fAcceptedElements

Accepted elements.

fRemovedElements

protected java.util.Hashtable fRemovedElements

Removed elements.

fElementDepth
```
protected int fElementDepth
```
The element depth.

fRemovalElementDepth
```
protected int fRemovalElementDepth
```
The element depth at element removal.

Constructor Detail
- ElementRemover
```
public ElementRemover()
```

Method Detail

acceptElement
```
public void acceptElement(java.lang.String element,
                 java.lang.String[] attributes)
```
Specifies that the given element should be accepted and, optionally, which attributes of that element should be kept.

Parameters:
element - The element to accept.
attributes - The list of attributes to be kept or null if no attributes should be kept for this element. see #removeElement

removeElement
```
public void removeElement(java.lang.String element)
```
Specifies that the given element should be completely removed. If an element is encountered during processing that is on the remove list, the element's start and end tags as well as all of content contained within the element will be removed from the processing stream.

Parameters:
element - The element to completely remove.

startDocument

public void startDocument(XMLLocator locator,
                 java.lang.String encoding,
                 NamespaceContext nscontext,
                 Augmentations augs)
                   throws XNIException

Start document.

Overrides:: startDocument in class DefaultFilter
Throws:: XNIException

startDocument

public void startDocument(XMLLocator locator,
                 java.lang.String encoding,
                 Augmentations augs)
                   throws XNIException

Start document.

Overrides:: startDocument in class DefaultFilter
Throws:: XNIException

startPrefixMapping

public void startPrefixMapping(java.lang.String prefix,
                      java.lang.String uri,
                      Augmentations augs)
                        throws XNIException

Start prefix mapping.

Overrides:: startPrefixMapping in class DefaultFilter
Throws:: XNIException

startElement

public void startElement(QName element,
                XMLAttributes attributes,
                Augmentations augs)
                  throws XNIException

Start element.

Overrides:: startElement in class DefaultFilter
Throws:: XNIException

emptyElement

public void emptyElement(QName element,
                XMLAttributes attributes,
                Augmentations augs)
                  throws XNIException

Empty element.

Overrides:: emptyElement in class DefaultFilter
Throws:: XNIException

comment

public void comment(XMLString text,
           Augmentations augs)
             throws XNIException

Comment.

Overrides:: comment in class DefaultFilter
Throws:: XNIException

processingInstruction

public void processingInstruction(java.lang.String target,
                         XMLString data,
                         Augmentations augs)
                           throws XNIException

Processing instruction.

Overrides:: processingInstruction in class DefaultFilter
Throws:: XNIException

characters

public void characters(XMLString text,
              Augmentations augs)
                throws XNIException

Characters.

Overrides:: characters in class DefaultFilter
Throws:: XNIException

ignorableWhitespace

public void ignorableWhitespace(XMLString text,
                       Augmentations augs)
                         throws XNIException

Ignorable whitespace.

Overrides:: ignorableWhitespace in class DefaultFilter
Throws:: XNIException

startGeneralEntity

public void startGeneralEntity(java.lang.String name,
                      XMLResourceIdentifier id,
                      java.lang.String encoding,
                      Augmentations augs)
                        throws XNIException

Start general entity.

Overrides:: startGeneralEntity in class DefaultFilter
Throws:: XNIException

textDecl

public void textDecl(java.lang.String version,
            java.lang.String encoding,
            Augmentations augs)
              throws XNIException

Text declaration.

Overrides:: textDecl in class DefaultFilter
Throws:: XNIException

endGeneralEntity

public void endGeneralEntity(java.lang.String name,
                    Augmentations augs)
                      throws XNIException

End general entity.

Overrides:: endGeneralEntity in class DefaultFilter
Throws:: XNIException

startCDATA
```
public void startCDATA(Augmentations augs)
                throws XNIException
```
Start CDATA section.

Overrides:

startCDATA in class DefaultFilter

Throws:

XNIException

endCDATA
```
public void endCDATA(Augmentations augs)
              throws XNIException
```
End CDATA section.

Overrides:

endCDATA in class DefaultFilter

Throws:

XNIException

endElement

public void endElement(QName element,
              Augmentations augs)
                throws XNIException

End element.

Overrides:: endElement in class DefaultFilter
Throws:: XNIException

endPrefixMapping

public void endPrefixMapping(java.lang.String prefix,
                    Augmentations augs)
                      throws XNIException

End prefix mapping.

Overrides:: endPrefixMapping in class DefaultFilter
Throws:: XNIException

elementAccepted
```
protected boolean elementAccepted(java.lang.String element)
```
Returns true if the specified element is accepted.

elementRemoved
```
protected boolean elementRemoved(java.lang.String element)
```
Returns true if the specified element should be removed.

handleOpenTag

protected boolean handleOpenTag(QName element,
                    XMLAttributes attributes)

Handles an open tag.

Class ElementRemover

Field Summary

Fields inherited from class org.cyberneko.html.filters.DefaultFilter

Constructor Summary

Method Summary

Methods inherited from class org.cyberneko.html.filters.DefaultFilter

Methods inherited from class java.lang.Object

Field Detail

NULL

fAcceptedElements

fRemovedElements

fElementDepth

fRemovalElementDepth

Constructor Detail

ElementRemover

Method Detail

acceptElement

removeElement

startDocument

startDocument

startPrefixMapping

startElement

emptyElement

comment

processingInstruction

characters

ignorableWhitespace

startGeneralEntity

textDecl

endGeneralEntity

startCDATA

endCDATA

endElement

endPrefixMapping

elementAccepted

elementRemoved

handleOpenTag