SAX

SAX, the Simple API for XML, is an event-driven API that, rather than modeling the document, models the parser and the client application that receives information from the parser. It's suitable for documents that are fairly localthat is, situations in which processing one piece of the document does not depend heavily on content from other pieces of the document. It is extremely fast, and far and away the most memory efficient of the various XML APIs. It is the only API that can easily handle documents in the multi-gigabyte range.

SAX is divided into three packages:

• org.xml.sax : the core classes and interfaces that all SAX parsers and most SAX programs use

• org.xml.sax.helpers : factory classes for loading instances of the core SAX interfaces, as well as some implementations of those interfaces

• org.xml.sax.ext : optional extensions to SAX, which not all parsers provide

org.xml.sax

The org.xml.sax package contains the core classes and interfaces that represent the parser, the client application, the input document, and more. It also contains a number of classes from SAX1 that can be safely ignored in modern applications.

AttributeList

The AttributeList interface was used in SAX1 to pass attribute sets to the startElement() method of DocumentHandler . It is now deprecated and should not be used.

 package org.xml.sax;  public interface  AttributeList  {   public int  getLength  ();   public String  getName  (int  i  );   public String  getType  (int  i  );   public String  getValue  (int  i  );   public String  getType  (String  name  );   public String  getValue  (String  name  ); } 

Attributes

The Attributes interface is used to pass attribute sets to the startElement() method of ContentHandler Although list-like, indexed access is supported for convenience, there is absolutely no guarantee that the attributes will be stored in the list in the order they appear in the start-tag. Indeed, in practice it's more likely than not that they won't be. If the attribute is declared to have any type other than CDATA (for example, ID, NMTOKENS, or enumerated) and the parser has read the DTD, then the reported value is normalized; that is, leading and trailing white space is trimmed , and runs of white space are converted to single space. The unnormalized value will not be available. Undeclared attributes are not normalized.

 package org.xml.sax;  public interface  Attributes  {   public int  getLength  ();   public String  getURI  (int  index  );   public String  getLocalName  (int  index  );   public String  getQName  (int  index  );   public String  getType  (int  index  );   public String  getValue  (int  index  );   public int  getIndex  (String  uri,  String  localName  );   public int  getIndex  (String  qualifiedName  );   public String  getType  (String  uri,  String  localName  );   public String  getType  (String  qualifiedName  );   public String  getValue  (String  uri,  String  localName  );   public String  getValue  (String  qualifiedName  ); } 

ContentHandler

ContentHandler is the basic callback interface a client application implements in order to receive information from the parser. Client applications register an instance of this interface with the parser using the setContentHandler() method in XMLReader . The parser will invoke the methods in that object in the same order that the corresponding markup and text appears in the original document.

Note

This interface has no relation to the moribund java.net.ContentHandler . But because the name does conflict, don't import java.net.* in a class that uses org.xml.sax.ContentHandler . Just import the classes you actually use.

 package org.xml.sax;  public interface  ContentHandler  {   public void  setDocumentLocator  (Locator  locator  );   public void  startDocument  ()    throws SAXException;   public void  endDocument  ()    throws SAXException;   public void  startPrefixMapping  (String  prefix,  String  uri  )    throws SAXException;   public void  endPrefixMapping  (String  prefix  )    throws SAXException;   public void  startElement  (String  namespaceURI,  String  localName,  String  qualifiedName,  Attributes  atts  ) throws SAXException;   public void  endElement  (String  namespaceURI,  String  localName,  String  qualifiedName  ) throws SAXException;   public void  characters  (char[]  text,  int  start,  int  length  )    throws SAXException;   public void  ignorableWhitespace  (char[]  space,  int  start,  int  length  ) throws SAXException;   public void  processingInstruction  (String  target,  String  data  )    throws SAXException;   public void  skippedEntity  (String  name  ) throws SAXException; } 

DocumentHandler

DocumentHandler is the SAX1 equivalent of ContentHandler . It is now deprecated and should not be used.

 package org.xml.sax;  public interface  DocumentHandler  {   public void  setDocumentLocator  (Locator  locator  );   public void  startDocument  () throws SAXException;   public void  endDocument  () throws SAXException;   public void  startElement  (String  name,  AttributeList  atts  )    throws SAXException;   public void  endElement  (String  name  ) throws SAXException;   public void  characters  (char[]  text,  int  start,  int  length  )    throws SAXException;   public void  ignorableWhitespace  (char[]  space,  int  start,  int  length  ) throws SAXException;   public void  processingInstruction  (String  target,  String  data  )    throws SAXException; } 

DTDHandler

DTDHandler is a callback interface that a client application can implement and register with the XMLReader using the setDTDHandler() method if it wishes to receive information from the parser about notations and unparsed entities declared in the DTD. These methods will be called sometime after startDocument() and again sometime before the startElement() method for the root element. You'll generally store the information in some data structure such as a Map so that you can refer back to it when you encounter an attribute with type NOTATION or ENTITY.

 package org.xml.sax;  public interface  DTDHandler  {   public void  notationDecl  (String  name,  String  publicID,  String  systemID  ) throws SAXException;   public void  unparsedEntityDecl  (String  name,  String  publicID,  String  systemID,  String  notationName  ) throws SAXException; } 

EntityResolver

A client program can implement the EntityResolver interface to substitute different sources for entities referenced in the main document by public or system ID. A specific instance of EntityResolver is registered with the parser by passing it to the setEntityResolver() method in XMLReader . If resolveEntity() cannot locate a requested entity, then it should return null, to tell the parser to use its default entity resolution mechanism.

 package org.xml.sax;  public interface  EntityResolver  {   public InputSource  resolveEntity  (String  publicID,  String  systemID  ) throws SAXException, IOException; } 

ErrorHandler

ErrorHandler is a callback interface that parsers use to report the three levels of errors that may be encountered while parsing an XML document: a fatal well- formedness error, a nonfatal error such as a validity violation, and a warning.

Parsers normally stop parsing the current document after reporting a fatal error. That is, the parser calls endDocument() and the parse() method returns. If you want the same behavior from a nonfatal error, then rethrow the exception from inside the error() method. You install a specific instance of this interface by passing it to the setErrorHandler() method in XMLReader .

 package org.xml.sax;  public interface  ErrorHandler  {   public void  warning  (SAXParseException  ex  ) throws SAXException;   public void  error  (SAXParseException  ex  ) throws SAXException;   public void  fatalError  (SAXParseException  ex  )    throws SAXException; } 

HandlerBase

HandlerBase is the SAX1 equivalent of DefaultHandler that is, an adapter class that provides do-nothing implementations of the SAX1 callback interfaces. It is now deprecated and should not be used.

 package org.xml.sax;  public class  HandlerBase  implements EntityResolver,  DTDHandler, DocumentHandler, ErrorHandler {   public  HandlerBase  ();   // EntityResolver methods   public InputSource  resolveEntity  (String  publicID,  String  systemID  ) throws SAXException;   // DTDHandler methods   public void  notationDecl  (String  name,  String  publicID,  String  systemID  );   public void  unparsedEntityDecl  (String  name,  String  publicID,  String  systemID,  String  notationName  );   // DocumentHandler methods   public void  setDocumentLocator  (Locator  locator  );   public void  startDocument  () throws SAXException;   public void  endDocument  () throws SAXException;   public void  startElement  (String  name,  AttributeList  attributes  )    throws SAXException;   public void  endElement  (String  name  ) throws SAXException;   public void  characters  (char[]  text,  int  start,  int  length  )    throws SAXException;   public void  ignorableWhitespace  (char[]  space,  int  start,  int  length  ) throws SAXException;   public void  processingInstruction  (String  target,  String  data  )    throws SAXException;   // ErrorHandler methods   public void  warning  (SAXParseException  ex  ) throws SAXException;   public void  error  (SAXParseException  ex  ) throws SAXException;   public void  fatalError  (SAXParseException  ex  )    throws SAXException; } 

InputSource

InputSource is a wrapper for the many things that may contain an XML document, including URLs, InputStream s, and Reader s. An InputSource should be configured with a system ID URL and either an InputStream or a Reader .

 package org.xml.sax;  public class  InputSource  {   public  InputSource  ();   public  InputSource  (String  systemID  );   public  InputSource  (InputStream  byteStream  );   public  InputSource  (Reader  characterStream  );   public void  setPublicId  (String  publicID  );   public String  getPublicId  ();   public void  setSystemId  (String  url  );   public String  getSystemId  ();   public void  setByteStream  (InputStream  in  );   public InputStream  getByteStream  ();   public void  setEncoding  (String  encoding  );   public String  getEncoding  ();   public void  setCharacterStream  (Reader  in  );   public Reader  getCharacterStream  (); } 

Remember always to set the system ID for an InputSource . If nothing else is set, then the parser will read the document from that URL. You also may set either the byte stream or the character stream, in which case that will be used to read the document. If you set both the byte stream and the character stream, then the parser will read from the character stream.

Locator

Many parsers pass a Locator object to the setLocator() method of ContentHandler before they call startDocument() . If a parser does this (and it's not required to), then client applications can use that Locator object to determine in which entity at which line and column a particular event occurs. The location information returned is not guaranteed to be perfectly accurate, but it's normally close enough to help in debugging.

 package org.xml.sax;  public interface  Locator  {   public String  getPublicId  ();   public String  getSystemId  ();   public int  getLineNumber  ();   public int  getColumnNumber  (); } 

Parser

Parser is the SAX1 class that represents an XML parser. Modern programs should use SAX2's XMLReader instead.

 package org.xml.sax;  public interface  Parser  {   public void  setLocale  (Locale  locale  ) throws SAXException;   public void  setEntityResolver  (EntityResolver  resolver  );   public void  setDTDHandler  (DTDHandler  handler  );   public void  setDocumentHandler  (DocumentHandler  handler  );   public void  setErrorHandler  (ErrorHandler  handler  );   public void  parse  (InputSource  source  )    throws SAXException, IOException;   public void  parse  (String  systemID  )    throws SAXException, IOException; } 

XMLFilter

XMLFilter is an XMLReader that receives its content from another XMLReader rather than directly from a parsed document. Thus it has the opportunity to modify, log, replace, or otherwise manipulate the content that the parser sends. Most of the time, it is much easier to write a filter by subclassing the org.xml.sax.helpers.XMLFilterImpl class rather than by implementing this interface directly.

 package org.xml.sax;  public interface  XMLFilter  implements XMLReader {   public void  setParent  (XMLReader  parent  );   public XMLReader  getParent  (); } 

XMLReader

XMLReader is SAX2's representation of an XML parser. It has methods to get and set features and properties, to configure the parser with the various handler classes, and to parse documents from an InputSource or a URL.

 package org.xml.sax;  public interface  XMLReader  {   public boolean  getFeature  (String  name  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public void  setFeature  (String  name,  boolean  value  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public Object  getProperty  (String  name  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public void  setProperty  (String  name,  Object  value  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public void  setEntityResolver  (EntityResolver  resolver  );   public EntityResolver  getEntityResolver  ();   public void  setDTDHandler  (DTDHandler  handler  );   public DTDHandler  getDTDHandler  ();   public void  setContentHandler  (ContentHandler  handler  );   public ContentHandler  getContentHandler  ();   public void  setErrorHandler  (ErrorHandler  handler  );   public ErrorHandler  getErrorHandler  ();   public void  parse  (InputSource  input  )    throws IOException, SAXException;   public void  parse  (String  systemID  )    throws IOException, SAXException; } 

Exceptions and Errors

All SAX exceptions are checked exceptions and all are derived from org.xml.sax.SAXException . In addition, a few methods that perform input/output can throw an IOException .

SAXException

SAXException is the generic checked exception for just about anything that can go wrong while parsing an XML document aside from an I/O error. Often a more specific subclass of SAXException will be thrown instead, even if the method is only declared to throw SAXException . The SAXException class predates Java 1.4 by a couple of years ; therefore, it uses its own getException() method to report the nested exception that caused the SAXException (if such exists), rather than the getCause() method introduced in Java 1.4.

 package org.xml.sax;  public class  SAXException  extends Exception {   public  SAXException  (String  message  );   public  SAXException  (Exception  ex  );   public  SAXException  (String  message,  Exception  ex  );   public String  getMessage  ();   public Exception  getException  ();   public String  toString  (); } 

SAXNotRecognizedException

A SAXNotRecognizedException signals that the parser does not support the feature or property you're trying to set; for example, you're trying to turn on validation for a nonvalidating parser.

 package org.xml.sax;  public class  SAXNotRecognizedException  extends SAXException {   public  SAXNotRecognizedException  (String  message  ); } 

SAXNotSupportedException

A SAXNotSupportedException indicates one of two things. Either the parser cannot set a feature or property to the requested value (for example, you're trying to set the value of the http://xml.org/sax/properties/lexical-handler property to an object that does not implement LexicalHandler ), or it cannot set that feature or property at this point in time (for example, you're trying to turn on validation when the parser is halfway through the document).

 package org.xml.sax;  public class  SAXNotSupportedException  extends SAXException {   public  SAXNotSupportedException  (String  message  ); } 

SAXParseException

A SAXParseException normally indicates a well-formedness error. In ErrorHandler it is also used to indicate validity errors, other nonfatal errors, and warnings. It normally provides line and column numbers locating the position of the error in the XML document that caused the exception. However, sometimes these are set to -1 if the error occurs very early in the document or if the parser can't determine exactly where the problem is.

 package org.xml.sax;  public class  SAXParseException  extends SAXException {   public  SAXParseException  (String  message,  Locator  locator  );   public  SAXParseException  (String  message,  Locator  locator,  Exception  e  );   public  SAXParseException  (String  message,  String  publicID,  String  systemID,  int  lineNumber,  int  columnNumber  );   public  SAXParseException  (String  message,  String  publicID,  String  systemID,  int  lineNumber,  int  columnNumber,  Exception  e  );   public String  getPublicId  ();   public String  getSystemId  ();   public int  getLineNumber  ();   public int  getColumnNumber  (); } 

org.xml.sax.ext

The org.xml.sax.ext package contains optional extensions to SAX that parsers are not required to implement. In practice, the major parsers do implement the DeclHandler and LexicalHandler callback interfaces from this package.

DeclHandler

DeclHandler is a callback interface that client applications can implement and register with the parser in order to receive notification of element, attribute, and parsed entity declarations. Parsers are not required to provide this information, but most validating parsers do. If a LexicalHandler is also installed, then all calls to these methods occur in between the calls to startDTD() and endDTD() .

A DeclHandler is installed in an XMLReader as the value of the http://xml.org/sax/properties/declaration-handler property with the setProperty() method. Parsers that do not provide declaration events will throw a SAXNotRecognizedException when you do this.

 package org.xml.sax.ext;  public interface  DeclHandler  {   public void  elementDecl  (String  name,  String  model  )    throws SAXException;   public void  attributeDecl  (String  elementName,  String  attributeName,  String  type,  String  valueDefault,  String  value  ) throws SAXException;   public void  internalEntityDecl  (String  name,  String  value  )    throws SAXException;   public void  externalEntityDecl  (String  name,  String  publicID,  String  systemID  ) throws SAXException; } 

LexicalHandler

LexicalHandler is a callback interface that client applications can implement and register with the parser in order to receive notification of lexical information such as comments, parsed entities, and CDATA section boundaries. Parsers are not required to provide lexical information, but most do. In normal usage, this interface is not uncommon. Excessive reliance on it often indicates a poorly designed XML application.

A LexicalHandler is installed in an XMLReader as the value of the http://xml.org/sax/properties/lexical-handler property with the setProperty() method. Parsers that do not provide lexical events will throw a SAXNotRecognizedException when you do this.

 package org.xml.sax.ext;  public interface  LexicalHandler  {   public void  startDTD  (String  name,  String  publicID,  String  systemID  ) throws SAXException;   public void  endDTD  () throws SAXException;   public void  startEntity  (String  name  ) throws SAXException;   public void  endEntity  (String  name  ) throws SAXException;   public void  startCDATA  () throws SAXException;   public void  endCDATA  () throws SAXException;   public void  comment  (char[]  text,  int  start,  int  length  )    throws SAXException; } 

org.xml.sax.helpers

The org.xml.sax.helpers package contains classes that may assist with many SAX tasks but are not necessarily required. The ones that client developers will find most useful are the factory classes for locating XMLReader s, but there are also classes that provide minimal implementations of several SAX interfaces, such as Attributes that can be useful when writing filters.

AttributeListImpl

The legacy AttributeListImpl class is a SAX1 class that parser vendors may (or may not) use to implement the AttributesList interface. There's little to no need for this in SAX2.

 package org.xml.sax.helpers;  public class  AttributeListImpl  implements AttributeList {   public  AttributeListImpl  ();   public  AttributeListImpl  (AttributeList  atts  );   public int  getLength  ();   public String  getName  (int  i  );   public String  getType  (int  i  );   public String  getValue  (int  i  );   public String  getType  (String  name  );   public String  getValue  (String  name  );   public void  setAttributeList  (AttributeList  atts  );   public void  addAttribute  (String  name,  String  type,  String  value  );   public void  removeAttribute  (String  name  );   public void  clear  (); } 

AttributesImpl

AttributesImpl is a class that parser vendors may (or may not) use to implement the Attributes interface. It can also be useful for taking persistent snapshots of Attributes objects and modifying Attributes lists in filters.

 package org.xml.sax.helpers;  public class  AttributesImpl  implements Attributes {   public  AttributesImpl  ();   public  AttributesImpl  (Attributes  atts  );   public int  getLength  ();   public String  getURI  (int  index  );   public String  getLocalName  (int  index  );   public String  getQName  (int  index  );   public String  getType  (int  index  );   public String  getValue  (int  index  );   public void  removeAttribute  (int  index  );   public void  setURI  (int  index,  String  uri  );   public void  setLocalName  (int  index,  String  localName  );   public void  setQName  (int  index,  String  qualifiedName  );   public void  setType  (int  index,  String  type  );   public void  setValue  (int  index,  String  value  );   public int  getIndex  (String  uri,  String  localName  );   public int  getIndex  (String  qualifiedName  );   public String  getType  (String  uri,  String  localName  );   public String  getType  (String  qualifiedName  );   public String  getValue  (String  uri,  String  localName  );   public String  getValue  (String  qualifiedName  );   public void  clear  ();   public void  setAttributes  (Attributes  atts  );   public void  addAttribute  (String  uri,  String  localName,  String  qualifiedName,  String  type,  String  value  );   public void  setAttribute  (int  index,  String  uri,  String  localName,  String  qualifiedName,  String  type,  String  value  ); } 

DefaultHandler

DefaultHandler is an adapter class that implements the four required SAX2 callback interfaces EntityResolver , DTDHandler , ContentHandler , and ErrorHandler with do-nothing implementations of all of their methods. It's often more convenient to subclass this class rather than implement those interfaces directly.

 package org.xml.sax.helpers;  public class  DefaultHandler  implements EntityResolver,  DTDHandler, ContentHandler, ErrorHandler {   public  DefaultHandler  ();   // EntityResolver methods   public InputSource  resolveEntity  (String  publicID,  String  systemID  ) throws SAXException;   // DTDHandler methods   public void  notationDecl  (String  name,  String  publicID,  String  systemID  ) throws SAXException;   public void  unparsedEntityDecl  (String  name,  String  publicID,  String  systemID,  String  notationName  ) throws SAXException;   // ContentHandler methods   public void  setDocumentLocator  (Locator  locator  );   public void  startDocument  () throws SAXException;   public void  endDocument  () throws SAXException;   public void  startPrefixMapping  (String  prefix,  String  uri  )    throws SAXException;   public void  endPrefixMapping  (String  prefix  )    throws SAXException;   public void  startElement  (String  uri,  String  localName,  String  qualifiedName,  Attributes  attributes  )    throws SAXException;   public void  endElement  (String  uri,  String  localName,  String  qualifiedName  ) throws SAXException;   public void  characters  (char[]  text,  int  start,  int  length  )    throws SAXException;   public void  ignorableWhitespace  (char[]  space,  int  start,  int  length  ) throws SAXException;   public void  processingInstruction  (String  target,  String  data  )    throws SAXException;   public void  skippedEntity  (String  name  ) throws SAXException;   // ErrorHandler methods   public void  warning  (SAXParseException  e  ) throws SAXException;   public void  error  (SAXParseException  e  ) throws SAXException;   public void  fatalError  (SAXParseException  e  ) throws SAXException; } 

LocatorImpl

LocatorImpl is a class that parser vendors may implement to help them provide the optional Locator interface. There's little reason for most developers to use it, although occasionally it may be useful if you want to provide pseudo-location information from a filter or nonparser-based XMLReader , or if you want to take a persistent snapshot of location information at some point in the parse process.

 package org.xml.sax.helpers;  public class  LocatorImpl  implements Locator {   public  LocatorImpl  ();   public  LocatorImpl  (Locator  locator  );   public String  getPublicId  ();   public String  getSystemId  ();   public int  getLineNumber  ();   public int  getColumnNumber  ();   public void  setPublicId  (String  publicID  );   public void  setSystemId  (String  systemID  );   public void  setLineNumber  (int  lineNumber  );   public void  setColumnNumber  (int  columnNumber  ); } 

NamespaceSupport

The NamespaceSupport class provides a stack for storing namespace-prefix-to-URI mappings. It's useful when a program needs to resolve namespace prefixes that occur in attribute values and element content. You can reuse a NamespaceSupport object for multiple documents, but if you do so, you need to call reset() in between documents (typically in startDocument() ).

 package org.xml.sax.helpers;  public class  NamespaceSupport  {   public static final String  XMLNS;  public  NamespaceSupport  ();   public void  reset  ();   public void  pushContext  ();   public void  popContext  ();   public boolean  declarePrefix  (String  prefix,  String  uri  );   public String[]  processName  (String  qualifiedName,  String  parts,  boolean  isAttribute  );   public String  getURI  (String  prefix  );   public Enumeration  getPrefixes  ();   public String  getPrefix  (String  uri  );   public Enumeration  getPrefixes  (String  uri  );   public Enumeration  getDeclaredPrefixes  (); } 

ParserAdapter

ParserAdapter uses the adapter design pattern to convert SAX1 Parser objects into SAX2 XMLReader objects. Given the large number of high-quality , native SAX2 parsers now available, there's little reason to use this class anymore.

 package org.xml.sax.helpers;  public class  ParserAdapter  implements XMLReader, DocumentHandler {   public  ParserAdapter  () throws SAXException;   public  ParserAdapter  (Parser  parser  );   // XMLReader methods   public void  setFeature  (String  name,  boolean  state  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public boolean  getFeature  (String  name  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public void  setProperty  (String  name,  Object  value  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public Object  getProperty  (String  name  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public void  setEntityResolver  (EntityResolver  resolver  );   public EntityResolver  getEntityResolver  ();   public void  setDTDHandler  (DTDHandler  handler  );   public DTDHandler  getDTDHandler  ();   public void  setContentHandler  (ContentHandler  handler  );   public ContentHandler  getContentHandler  ();   public void  setErrorHandler  (ErrorHandler  handler  );   public ErrorHandler  getErrorHandler  ();   public void  parse  (String  systemID  )    throws IOException, SAXException;   public void  parse  (InputSource  input  )    throws IOException, SAXException;   // DocumentHandler methods   public void  setDocumentLocator  (Locator  locator  );   public void  startDocument  () throws SAXException;   public void  endDocument  () throws SAXException;   public void  startElement  (String  qualifiedName,  AttributeList  qAtts  ) throws SAXException;   public void  endElement  (String  qualifiedName  )    throws SAXException;   public void  characters  (char[]  text,  int  start,  int  length  )    throws SAXException;   public void  ignorableWhitespace  (char[]  space,  int  start,  int  length  ) throws SAXException;   public void  processingInstruction  (String  target,  String  data  )    throws SAXException; } 

ParserFactory

ParserFactory is a factory class used to create implementation-specific instances of the SAX1 Parser class. The org.xml.sax.parser Java system property determines its default implementation. ParserFactory is now deprecated like the rest of SAX1 and should no longer be used.

 package org.xml.sax.helpers;  public class  ParserFactory  {   public static Parser  makeParser  ()    throws ClassNotFoundException, IllegalAccessException,           InstantiationException, NullPointerException,           ClassCastException;   public static Parser  makeParser  (String  className  )    throws ClassNotFoundException, IllegalAccessException,           InstantiationException, ClassCastException; } 

XMLFilterImpl

Although there is a more generic XMLFilter interface, XMLFilterImpl is the class you should actually subclass to implement SAX filters. The parent XMLReader is the object from which the filter will receive its information. By default, all of the methods in this class simply delegate to the parent's equivalent methods or objects, but you can override any or all of them to perform the filtering.

 package org.xml.sax.helpers;  public class  XMLFilterImpl  implements XMLFilter, EntityResolver, DTDHandler,             ContentHandler, ErrorHandler {   public  XMLFilterImpl  ();   public  XMLFilterImpl  (XMLReader  parent  );   public void  setParent  (XMLReader  parent  );   public XMLReader  getParent  ();   // XMLReader methods   public void  setFeature  (String  name,  boolean  state  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public boolean  getFeature  (String  name  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public void  setProperty  (String  name,  Object  value  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public Object  getProperty  (String  name  )    throws SAXNotRecognizedException, SAXNotSupportedException;   public void  setEntityResolver  (EntityResolver  resolver  );   public EntityResolver  getEntityResolver  ();   public void  setDTDHandler  (DTDHandler  handler  );   public DTDHandler  getDTDHandler  ();   public void  setContentHandler  (ContentHandler  handler  );   public ContentHandler  getContentHandler  ();   public void  setErrorHandler  (ErrorHandler  handler  );   public ErrorHandler  getErrorHandler  ();   public void  parse  (InputSource  input  )    throws SAXException, IOException;   public void  parse  (String  systemID  )    throws SAXException, IOException;   // EntityResolver methods   public InputSource  resolveEntity  (String  publicID,  String  systemID  ) throws SAXException, IOException;   // DTDHandler methods   public void  notationDecl  (String  name,  String  publicID,  String  systemID  ) throws SAXException;   public void  unparsedEntityDecl  (String  name,  String  publicID,  String  systemID,  String  notationName  ) throws SAXException;   // ContentHandler methods   public void  setDocumentLocator  (Locator  locator  );   public void  startDocument  () throws SAXException;   public void  endDocument  () throws SAXException;   public void  startPrefixMapping  (String  prefix,  String  uri  )    throws SAXException;   public void  endPrefixMapping  (String  prefix  )    throws SAXException;   public void  startElement  (String  uri,  String  localName,  String  qualifiedName,  Attributes  atts  ) throws SAXException;   public void  endElement  (String  uri,  String  localName,  String  qualifiedName  ) throws SAXException;   public void  characters  (char[]  text,  int  start,  int  length  )    throws SAXException;   public void  ignorableWhitespace  (char[]  space,  int  start,  int  length  ) throws SAXException;   public void  processingInstruction  (String  target,  String  data  )    throws SAXException;   public void  skippedEntity  (String  name  ) throws SAXException;   // ErrorHandler methods   public void  warning  (SAXParseException  e  ) throws SAXException;   public void  error  (SAXParseException  e  ) throws SAXException;   public void  fatalError  (SAXParseException  e  )    throws SAXException; } 

XMLReaderAdapter

XMLReaderAdapter uses the adapter design pattern to convert SAX2 XMLReader objects into SAX1 Parser objects for compatibility with legacy code.

 package org.xml.sax.helpers;  public class  XMLReaderAdapter  implements Parser, ContentHandler {   public  XMLReaderAdapter  () throws SAXException;   public  XMLReaderAdapter  (XMLReader  xmlReader  );   // Parser methods   public void  setLocale  (Locale  locale  ) throws SAXException;   public void  setEntityResolver  (EntityResolver  resolver  );   public void  setDTDHandler  (DTDHandler  handler  );   public void  setDocumentHandler  (DocumentHandler  handler  );   public void  setErrorHandler  (ErrorHandler  handler  );   public void  parse  (String  systemID  )    throws IOException, SAXException;   public void  parse  (InputSource  input  )    throws IOException, SAXException;   // ContentHandler methods   public void  setDocumentLocator  (Locator  locator  );   public void  startDocument  () throws SAXException;   public void  endDocument  () throws SAXException;   public void  startPrefixMapping  (String  prefix,  String  uri  );   public void  endPrefixMapping  (String  prefix  );   public void  startElement  (String  uri,  String  localName,  String  qualifiedName,  Attributes  atts  ) throws SAXException;   public void  endElement  (String  uri,  String  localName,  String  qualifiedName  ) throws SAXException;   public void  characters  (char[]  text,  int  start,  int  length  )    throws SAXException;   public void  ignorableWhitespace  (char[]  space,  int  start,  int  length  ) throws SAXException;   public void  processingInstruction  (String  target,  String  data  )    throws SAXException;   public void  skippedEntity  (String  name  ) throws SAXException; } 

XMLReaderFactory

XMLReaderFactory is a factory class used to create implementation-specific instances of XMLReader . The org.xml.sax.driver Java system property determines the default implementation.

 package org.xml.sax.helpers;  public final class  XMLReaderFactory  {   public static XMLReader  createXMLReader  () throws SAXException;   public static XMLReader  createXMLReader  (String  className  )    throws SAXException; }