# Class XMLFilterImpl

java.lang.Object
org.xml.sax.helpers.XMLFilterImpl

All Implemented Interfaces:
  `ContentHandler`, `DTDHandler`, `EntityResolver`, `ErrorHandler`, `XMLFilter`, `XMLReader`

public class XMLFilterImpl extends Object implements XMLFilter, EntityResolver, DTDHandler, ContentHandler, ErrorHandler
Base class for deriving an XML filter.

This class is designed to sit between an `XMLReader` and the client application's event handlers. By default, it does nothing but pass requests up to the reader and events on to the handlers unmodified, but subclasses can override specific methods to modify the event stream or the configuration requests as they pass through.

Since:
  1.4, SAX 2.0
See Also:
  - `XMLFilter`
  - `XMLReader`
  - `EntityResolver`
  - `DTDHandler`
  - `ContentHandler`
  - `ErrorHandler`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `XMLFilterImpl()`
  Construct an empty XML filter, with no parent.
  `XMLFilterImpl(XMLReader parent)`
  Construct an XML filter with the specified parent.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `characters(char[] ch, int start, int length)`
  Filter a character data event.
  `void`
  `endDocument()`
  Filter an end document event.
  `void`
  `endElement(String uri, String localName, String qName)`
  Filter an end element event.
  `void`
  `endPrefixMapping(String prefix)`
  Filter an end Namespace prefix mapping event.
  `void`
  `error(SAXParseException e)`
  Filter an error event.
  `void`
  `fatalError(SAXParseException e)`
  Filter a fatal error event.
  `ContentHandler`
  `getContentHandler()`
  Get the content event handler.
  `DTDHandler`
  `getDTDHandler()`
  Get the current DTD event handler.
  `EntityResolver`
  `getEntityResolver()`
  Get the current entity resolver.
  `ErrorHandler`
  `getErrorHandler()`
  Get the current error event handler.
  `boolean`
  `getFeature(String name)`
  Look up the value of a feature.
  `XMLReader`
  `getParent()`
  Get the parent reader.
  `Object`
  `getProperty(String name)`
  Look up the value of a property.
  `void`
  `ignorableWhitespace(char[] ch, int start, int length)`
  Filter an ignorable whitespace event.
  `void`
  `notationDecl(String name, String publicId, String systemId)`
  Filter a notation declaration event.
  `void`
  `parse(String systemId)`
  Parse a document.
  `void`
  `parse(InputSource input)`
  Parse a document.
  `void`
  `processingInstruction(String target, String data)`
  Filter a processing instruction event.
  `InputSource`
  `resolveEntity(String publicId, String systemId)`
  Filter an external entity resolution.
  `void`
  `setContentHandler(ContentHandler handler)`
  Set the content event handler.
  `void`
  `setDocumentLocator(Locator locator)`
  Filter a new document locator event.
  `void`
  `setDTDHandler(DTDHandler handler)`
  Set the DTD event handler.
  `void`
  `setEntityResolver(EntityResolver resolver)`
  Set the entity resolver.
  `void`
  `setErrorHandler(ErrorHandler handler)`
  Set the error event handler.
  `void`
  `setFeature(String name, boolean value)`
  Set the value of a feature.
  `void`
  `setParent(XMLReader parent)`
  Set the parent reader.
  `void`
  `setProperty(String name, Object value)`
  Set the value of a property.
  `void`
  `skippedEntity(String name)`
  Filter a skipped entity event.
  `void`
  `startDocument()`
  Filter a start document event.
  `void`
  `startElement(String uri, String localName, String qName, Attributes atts)`
  Filter a start element event.
  `void`
  `startPrefixMapping(String prefix, String uri)`
  Filter a start Namespace prefix mapping event.
  `void`
  `unparsedEntityDecl(String name, String publicId, String systemId, String notationName)`
  Filter an unparsed entity declaration event.
  `void`
  `warning(SAXParseException e)`
  Filter a warning event.

  ### Methods declared in class java.lang.Object

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

  ### Methods declared in interface org.xml.sax.ContentHandler

  `declaration`

- ## Constructor Details

  - ### XMLFilterImpl

    public XMLFilterImpl()
    Construct an empty XML filter, with no parent.

    This filter will have no parent: you must assign a parent before you start a parse or do any configuration with setFeature or setProperty, unless you use this as a pure event consumer rather than as an `XMLReader`.

    See Also:
      - `XMLReader.setFeature(java.lang.String, boolean)`
      - `XMLReader.setProperty(java.lang.String, java.lang.Object)`
      - `setParent(org.xml.sax.XMLReader)`

  - ### XMLFilterImpl

    public XMLFilterImpl(XMLReader parent)
    Construct an XML filter with the specified parent.
    Parameters:
      `parent` - the specified parent
    See Also:
      - `setParent(org.xml.sax.XMLReader)`
      - `getParent()`

- ## Method Details

  - ### setParent

    public void setParent(XMLReader parent)
    Set the parent reader.

    This is the `XMLReader` from which this filter will obtain its events and to which it will pass its configuration requests. The parent may itself be another filter.

    If there is no parent reader set, any attempt to parse or to set or get a feature or property will fail.

    Specified by:
      `setParent` in interface `XMLFilter`
    Parameters:
      `parent` - The parent XML reader.
    See Also:
      - `getParent()`

  - ### getParent

    public XMLReader getParent()
    Get the parent reader.
    Specified by:
      `getParent` in interface `XMLFilter`
    Returns:
      The parent XML reader, or null if none is set.
    See Also:
      - `setParent(org.xml.sax.XMLReader)`

  - ### setFeature

    public void setFeature(String name, boolean value) throws SAXNotRecognizedException, SAXNotSupportedException
    Set the value of a feature.

    This will always fail if the parent is null.

    Specified by:
      `setFeature` in interface `XMLReader`
    Parameters:
      `name` - The feature name.
      `value` - The requested feature value.
    Throws:
      `SAXNotRecognizedException` - If the feature value can't be assigned or retrieved from the parent.
      `SAXNotSupportedException` - When the parent recognizes the feature name but cannot set the requested value.
    See Also:
      - `XMLReader.getFeature(java.lang.String)`

  - ### getFeature

    public boolean getFeature(String name) throws SAXNotRecognizedException, SAXNotSupportedException
    Look up the value of a feature.

    This will always fail if the parent is null.

    Specified by:
      `getFeature` in interface `XMLReader`
    Parameters:
      `name` - The feature name.
    Returns:
      The current value of the feature.
    Throws:
      `SAXNotRecognizedException` - If the feature value can't be assigned or retrieved from the parent.
      `SAXNotSupportedException` - When the parent recognizes the feature name but cannot determine its value at this time.
    See Also:
      - `XMLReader.setFeature(java.lang.String, boolean)`

  - ### setProperty

    public void setProperty(String name, Object value) throws SAXNotRecognizedException, SAXNotSupportedException
    Set the value of a property.

    This will always fail if the parent is null.

    Specified by:
      `setProperty` in interface `XMLReader`
    Parameters:
      `name` - The property name.
      `value` - The requested property value.
    Throws:
      `SAXNotRecognizedException` - If the property value can't be assigned or retrieved from the parent.
      `SAXNotSupportedException` - When the parent recognizes the property name but cannot set the requested value.

  - ### getProperty

    public Object getProperty(String name) throws SAXNotRecognizedException, SAXNotSupportedException
    Look up the value of a property.
    Specified by:
      `getProperty` in interface `XMLReader`
    Parameters:
      `name` - The property name.
    Returns:
      The current value of the property.
    Throws:
      `SAXNotRecognizedException` - If the property value can't be assigned or retrieved from the parent.
      `SAXNotSupportedException` - When the parent recognizes the property name but cannot determine its value at this time.
    See Also:
      - `XMLReader.setProperty(java.lang.String, java.lang.Object)`

  - ### setEntityResolver

    public void setEntityResolver(EntityResolver resolver)
    Set the entity resolver.
    Specified by:
      `setEntityResolver` in interface `XMLReader`
    Parameters:
      `resolver` - The new entity resolver.
    See Also:
      - `XMLReader.getEntityResolver()`

  - ### getEntityResolver

    public EntityResolver getEntityResolver()
    Get the current entity resolver.
    Specified by:
      `getEntityResolver` in interface `XMLReader`
    Returns:
      The current entity resolver, or null if none was set.
    See Also:
      - `XMLReader.setEntityResolver(org.xml.sax.EntityResolver)`

  - ### setDTDHandler

    public void setDTDHandler(DTDHandler handler)
    Set the DTD event handler.
    Specified by:
      `setDTDHandler` in interface `XMLReader`
    Parameters:
      `handler` - the new DTD handler
    See Also:
      - `XMLReader.getDTDHandler()`

  - ### getDTDHandler

    public DTDHandler getDTDHandler()
    Get the current DTD event handler.
    Specified by:
      `getDTDHandler` in interface `XMLReader`
    Returns:
      The current DTD handler, or null if none was set.
    See Also:
      - `XMLReader.setDTDHandler(org.xml.sax.DTDHandler)`

  - ### setContentHandler

    public void setContentHandler(ContentHandler handler)
    Set the content event handler.
    Specified by:
      `setContentHandler` in interface `XMLReader`
    Parameters:
      `handler` - the new content handler
    See Also:
      - `XMLReader.getContentHandler()`

  - ### getContentHandler

    public ContentHandler getContentHandler()
    Get the content event handler.
    Specified by:
      `getContentHandler` in interface `XMLReader`
    Returns:
      The current content handler, or null if none was set.
    See Also:
      - `XMLReader.setContentHandler(org.xml.sax.ContentHandler)`

  - ### setErrorHandler

    public void setErrorHandler(ErrorHandler handler)
    Set the error event handler.
    Specified by:
      `setErrorHandler` in interface `XMLReader`
    Parameters:
      `handler` - the new error handler
    See Also:
      - `XMLReader.getErrorHandler()`

  - ### getErrorHandler

    public ErrorHandler getErrorHandler()
    Get the current error event handler.
    Specified by:
      `getErrorHandler` in interface `XMLReader`
    Returns:
      The current error handler, or null if none was set.
    See Also:
      - `XMLReader.setErrorHandler(org.xml.sax.ErrorHandler)`

  - ### parse

    public void parse(InputSource input) throws SAXException, IOException
    Parse a document.
    Specified by:
      `parse` in interface `XMLReader`
    Parameters:
      `input` - The input source for the document entity.
    Throws:
      `SAXException` - Any SAX exception, possibly wrapping another exception.
      `IOException` - An IO exception from the parser, possibly from a byte stream or character stream supplied by the application.
    See Also:
      - `InputSource`
      - `XMLReader.parse(java.lang.String)`
      - `XMLReader.setEntityResolver(org.xml.sax.EntityResolver)`
      - `XMLReader.setDTDHandler(org.xml.sax.DTDHandler)`
      - `XMLReader.setContentHandler(org.xml.sax.ContentHandler)`
      - `XMLReader.setErrorHandler(org.xml.sax.ErrorHandler)`

  - ### parse

    public void parse(String systemId) throws SAXException, IOException
    Parse a document.
    Specified by:
      `parse` in interface `XMLReader`
    Parameters:
      `systemId` - The system identifier as a fully-qualified URI.
    Throws:
      `SAXException` - Any SAX exception, possibly wrapping another exception.
      `IOException` - An IO exception from the parser, possibly from a byte stream or character stream supplied by the application.
    See Also:
      - `XMLReader.parse(org.xml.sax.InputSource)`

  - ### resolveEntity

    public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException
    Filter an external entity resolution.
    Specified by:
      `resolveEntity` in interface `EntityResolver`
    Parameters:
      `publicId` - The entity's public identifier, or null.
      `systemId` - The entity's system identifier.
    Returns:
      A new InputSource or null for the default.
    Throws:
      `SAXException` - The client may throw an exception during processing.
      `IOException` - The client may throw an I/O-related exception while obtaining the new InputSource.
    See Also:
      - `InputSource`

  - ### notationDecl

    public void notationDecl(String name, String publicId, String systemId) throws SAXException
    Filter a notation declaration event.
    Specified by:
      `notationDecl` in interface `DTDHandler`
    Parameters:
      `name` - The notation name.
      `publicId` - The notation's public identifier, or null.
      `systemId` - The notation's system identifier, or null.
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `DTDHandler.unparsedEntityDecl(java.lang.String, java.lang.String, java.lang.String, java.lang.String)`
      - `Attributes`

  - ### unparsedEntityDecl

    public void unparsedEntityDecl(String name, String publicId, String systemId, String notationName) throws SAXException
    Filter an unparsed entity declaration event.
    Specified by:
      `unparsedEntityDecl` in interface `DTDHandler`
    Parameters:
      `name` - The entity name.
      `publicId` - The entity's public identifier, or null.
      `systemId` - The entity's system identifier, or null.
      `notationName` - The name of the associated notation.
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `DTDHandler.notationDecl(java.lang.String, java.lang.String, java.lang.String)`
      - `Attributes`

  - ### setDocumentLocator

    public void setDocumentLocator(Locator locator)
    Filter a new document locator event.
    Specified by:
      `setDocumentLocator` in interface `ContentHandler`
    Parameters:
      `locator` - The document locator.
    See Also:
      - `Locator`

  - ### startDocument

    public void startDocument() throws SAXException
    Filter a start document event.
    Specified by:
      `startDocument` in interface `ContentHandler`
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `ContentHandler.endDocument()`

  - ### endDocument

    public void endDocument() throws SAXException
    Filter an end document event.
    Specified by:
      `endDocument` in interface `ContentHandler`
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `ContentHandler.startDocument()`

  - ### startPrefixMapping

    public void startPrefixMapping(String prefix, String uri) throws SAXException
    Filter a start Namespace prefix mapping event.
    Specified by:
      `startPrefixMapping` in interface `ContentHandler`
    Parameters:
      `prefix` - The Namespace prefix.
      `uri` - The Namespace URI.
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `ContentHandler.endPrefixMapping(java.lang.String)`
      - `ContentHandler.startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)`

  - ### endPrefixMapping

    public void endPrefixMapping(String prefix) throws SAXException
    Filter an end Namespace prefix mapping event.
    Specified by:
      `endPrefixMapping` in interface `ContentHandler`
    Parameters:
      `prefix` - The Namespace prefix.
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `ContentHandler.startPrefixMapping(java.lang.String, java.lang.String)`
      - `ContentHandler.endElement(java.lang.String, java.lang.String, java.lang.String)`

  - ### startElement

    public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException
    Filter a start element event.
    Specified by:
      `startElement` in interface `ContentHandler`
    Parameters:
      `uri` - The element's Namespace URI, or the empty string.
      `localName` - The element's local name, or the empty string.
      `qName` - The element's qualified (prefixed) name, or the empty string.
      `atts` - The element's attributes.
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `ContentHandler.endElement(java.lang.String, java.lang.String, java.lang.String)`
      - `Attributes`
      - `AttributesImpl`

  - ### endElement

    public void endElement(String uri, String localName, String qName) throws SAXException
    Filter an end element event.
    Specified by:
      `endElement` in interface `ContentHandler`
    Parameters:
      `uri` - The element's Namespace URI, or the empty string.
      `localName` - The element's local name, or the empty string.
      `qName` - The element's qualified (prefixed) name, or the empty string.
    Throws:
      `SAXException` - The client may throw an exception during processing.

  - ### characters

    public void characters(char[] ch, int start, int length) throws SAXException
    Filter a character data event.
    Specified by:
      `characters` in interface `ContentHandler`
    Parameters:
      `ch` - An array of characters.
      `start` - The starting position in the array.
      `length` - The number of characters to use from the array.
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `ContentHandler.ignorableWhitespace(char[], int, int)`
      - `Locator`

  - ### ignorableWhitespace

    public void ignorableWhitespace(char[] ch, int start, int length) throws SAXException
    Filter an ignorable whitespace event.
    Specified by:
      `ignorableWhitespace` in interface `ContentHandler`
    Parameters:
      `ch` - An array of characters.
      `start` - The starting position in the array.
      `length` - The number of characters to use from the array.
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `ContentHandler.characters(char[], int, int)`

  - ### processingInstruction

    public void processingInstruction(String target, String data) throws SAXException
    Filter a processing instruction event.
    Specified by:
      `processingInstruction` in interface `ContentHandler`
    Parameters:
      `target` - The processing instruction target.
      `data` - The text following the target.
    Throws:
      `SAXException` - The client may throw an exception during processing.

  - ### skippedEntity

    public void skippedEntity(String name) throws SAXException
    Filter a skipped entity event.
    Specified by:
      `skippedEntity` in interface `ContentHandler`
    Parameters:
      `name` - The name of the skipped entity.
    Throws:
      `SAXException` - The client may throw an exception during processing.

  - ### warning

    public void warning(SAXParseException e) throws SAXException
    Filter a warning event.
    Specified by:
      `warning` in interface `ErrorHandler`
    Parameters:
      `e` - The warning as an exception.
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `SAXParseException`

  - ### error

    public void error(SAXParseException e) throws SAXException
    Filter an error event.
    Specified by:
      `error` in interface `ErrorHandler`
    Parameters:
      `e` - The error as an exception.
    Throws:
      `SAXException` - The client may throw an exception during processing.
    See Also:
      - `SAXParseException`

  - ### fatalError

    public void fatalError(SAXParseException e) throws SAXException
    Filter a fatal error event.
    Specified by:
      `fatalError` in interface `ErrorHandler`
    Parameters:
      `e` - The error as an exception.
    Throws:
      `SAXException` - The client may throw an exception during processing.