Module java.xml
Package org.xml.sax.ext

## Class DefaultHandler2

- java.lang.Object
- - org.xml.sax.helpers.DefaultHandler
  - - org.xml.sax.ext.DefaultHandler2

- All Implemented Interfaces:
    `ContentHandler`, `DTDHandler`, `EntityResolver`, `ErrorHandler`, `DeclHandler`, `EntityResolver2`, `LexicalHandler`

      public class DefaultHandler2
      extends DefaultHandler
      implements LexicalHandler, DeclHandler, EntityResolver2

  This class extends the SAX2 base handler class to support the SAX2 `LexicalHandler`, `DeclHandler`, and `EntityResolver2` extensions. Except for overriding the original SAX1 `resolveEntity()` method the added handler methods just return. Subclassers may override everything on a method-by-method basis.

  > This module, both source code and documentation, is in the Public Domain, and comes with NO WARRANTY.

  Note: this class might yet learn that the ContentHandler.setDocumentLocator() call might be passed a `Locator2` object, and that the ContentHandler.startElement() call might be passed a `Attributes2` object.

  Since:
    1.5, SAX 2.0 (extensions 1.1 alpha)

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `DefaultHandler2()` | Constructs a handler which ignores all parsing events.

  - ### Method Summary

    Modifier and Type | Method | Description
    --- | --- | ---
    `InputSource` | `getExternalSubset​(String name, String baseURI)` | Tells the parser that if no external subset has been declared in the document text, none should be used.
    `InputSource` | `resolveEntity​(String publicId, String systemId)` | Invokes `EntityResolver2.resolveEntity()` with null entity name and base URI.
    `InputSource` | `resolveEntity​(String name, String publicId, String baseURI, String systemId)` | Tells the parser to resolve the systemId against the baseURI and read the entity text from that resulting absolute URI.

    - ### Methods declared in class org.xml.sax.helpers.DefaultHandler

      `characters, endDocument, endElement, endPrefixMapping, error, fatalError, ignorableWhitespace, notationDecl, processingInstruction, setDocumentLocator, skippedEntity, startDocument, startElement, startPrefixMapping, unparsedEntityDecl, warning`

    - ### 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.ext.DeclHandler

      `attributeDecl, elementDecl, externalEntityDecl, internalEntityDecl`

    - ### Methods declared in interface org.xml.sax.ext.LexicalHandler

      `comment, endCDATA, endDTD, endEntity, startCDATA, startDTD, startEntity`

- - ### Constructor Detail

    - #### DefaultHandler2

          public DefaultHandler2()

      Constructs a handler which ignores all parsing events.

  - ### Method Detail

    - #### getExternalSubset

          public InputSource getExternalSubset​(String name,
                                               String baseURI)
                                        throws SAXException,
                                               IOException

      Tells the parser that if no external subset has been declared in the document text, none should be used.
      Specified by:
        `getExternalSubset` in interface `EntityResolver2`
      Parameters:
        `name` - Identifies the document root element. This name comes from a DOCTYPE declaration (where available) or from the actual root element.
        `baseURI` - The document's base URI, serving as an additional hint for selecting the external subset. This is always an absolute URI, unless it is null because the XMLReader was given an InputSource without one.
      Returns:
        An InputSource object describing the new external subset to be used by the parser, or null to indicate that no external subset is provided.
      Throws:
        `SAXException` - Any SAX exception, possibly wrapping another exception.
        `IOException` - Probably indicating a failure to create a new InputStream or Reader, or an illegal URL.

    - #### resolveEntity

          public InputSource resolveEntity​(String name,
                                           String publicId,
                                           String baseURI,
                                           String systemId)
                                    throws SAXException,
                                           IOException

      Tells the parser to resolve the systemId against the baseURI and read the entity text from that resulting absolute URI. Note that because the older `DefaultHandler.resolveEntity()`, method is overridden to call this one, this method may sometimes be invoked with null name and baseURI, and with the systemId already absolutized.
      Specified by:
        `resolveEntity` in interface `EntityResolver2`
      Parameters:
        `name` - Identifies the external entity being resolved. Either "[dtd]" for the external subset, or a name starting with "%" to indicate a parameter entity, or else the name of a general entity. This is never null when invoked by a SAX2 parser.
        `publicId` - The public identifier of the external entity being referenced (normalized as required by the XML specification), or null if none was supplied.
        `baseURI` - The URI with respect to which relative systemIDs are interpreted. This is always an absolute URI, unless it is null (likely because the XMLReader was given an InputSource without one). This URI is defined by the XML specification to be the one associated with the "<" starting the relevant declaration.
        `systemId` - The system identifier of the external entity being referenced; either a relative or absolute URI. This is never null when invoked by a SAX2 parser; only declared entities, and any external subset, are resolved by such parsers.
      Returns:
        An InputSource object describing the new input source to be used by the parser. Returning null directs the parser to resolve the system ID against the base URI and open a connection to resulting URI.
      Throws:
        `SAXException` - Any SAX exception, possibly wrapping another exception.
        `IOException` - Probably indicating a failure to create a new InputStream or Reader, or an illegal URL.

    - #### resolveEntity

          public InputSource resolveEntity​(String publicId,
                                           String systemId)
                                    throws SAXException,
                                           IOException

      Invokes `EntityResolver2.resolveEntity()` with null entity name and base URI. You only need to override that method to use this class.
      Specified by:
        `resolveEntity` in interface `EntityResolver`
      Overrides:
        `resolveEntity` in class `DefaultHandler`
      Parameters:
        `publicId` - The public identifier, or null if none is available.
        `systemId` - The system identifier provided in the XML document.
      Returns:
        The new input source, or null to require the default behaviour.
      Throws:
        `SAXException` - Any SAX exception, possibly wrapping another exception.
        `IOException` - If there is an error setting up the new input source.
      See Also:
        `EntityResolver.resolveEntity(java.lang.String, java.lang.String)`