// ContentHandler.java - handle main document content.
// Written by David Megginson, sax@megginson.com
// NO WARRANTY! This class is in the public domain.
// $Id: ContentHandler.java,v 1.5 2000/05/05 17:45:39 david Exp $
package org.xml.sax;
/**
* Receive notification of the logical content of a document.
*
* <blockquote>
* <em>This module, both source code and documentation, is in the
* Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
* </blockquote>
*
* <p>This is the main interface that most SAX applications
* implement: if the application needs to be informed of basic parsing
* events, it implements this interface and registers an instance with
* the SAX parser using the {@link XMLReader#setContentHandler
* setContentHandler} method. The parser uses the instance to report
* basic document-related events like the start and end of elements
* and character data.</p>
*
* <p>The order of events in this interface is very important, and
* mirrors the order of information in the document itself. For
* example, all of an element's content (character data, processing
* instructions, and/or subelements) will appear, in order, between
* the startElement event and the corresponding endElement event.</p>
*
* <p>This interface is similar to the now-deprecated SAX 1.0
* DocumentHandler interface, but it adds support for Namespaces
* and for reporting skipped entities (in non-validating XML
* processors).</p>
*
* <p>Implementors should note that there is also a Java class
* {@link java.net.ContentHandler ContentHandler} in the java.net
* package; that means that it's probably a bad idea to do</p>
*
* <blockquote>
* import java.net.*;
* import org.xml.sax.*;
* </blockquote>
*
* <p>In fact, "import ...*" is usually a sign of sloppy programming
* anyway, so the user should consider this a feature rather than a
* bug.</p>
*
* @since SAX 2.0
* @author David Megginson,
* <a href="mailto:sax@megginson.com">sax@megginson.com</a>
* @version 2.0
* @see XMLReader
* @see DTDHandler
* @see ErrorHandler
*/
public interface ContentHandler
{
/**
* Receive an object for locating the origin of SAX document events.
*
* <p>SAX parsers are strongly encouraged (though not absolutely
* required) to supply a locator: if it does so, it must supply
* the locator to the application by invoking this method before
* invoking any of the other methods in the ContentHandler
* interface.</p>
*
* <p>The locator allows the application to determine the end
* position of any document-related event, even if the parser is
* not reporting an error. Typically, the application will
* use this information for reporting its own errors (such as
* character content that does not match an application's
* business rules). The information returned by the locator
* is probably not sufficient for use with a search engine.</p>
*
* <p>Note that the locator will return correct information only
* during the invocation of the events in this interface. The
* application should not attempt to use it at any other time.</p>
*
* @param locator An object that can return the location of
* any SAX document event.
* @see Locator
*/
public void setDocumentLocator(Locator locator);
/**
* Receive notification of the beginning of a document.
*
* <p>The SAX parser will invoke this method only once, before any
* other methods in this interface or in {@link DTDHandler
* DTDHandler} (except for {@link #setDocumentLocator
* setDocumentLocator}).</p>
*
* @exception SAXException Any SAX exception, possibly
* wrapping another exception.
* @see #endDocument
*/
public void startDocument()
throws SAXException;
/**
* Receive notification of the end of a document.
*
* <p>The SAX parser will invoke this method only once, and it will
* be the last method invoked during the parse. The parser shall
* not invoke this method until it has either abandoned parsing
* (because of an unrecoverable error) or reached the end of
* input.</p>
*
* @exception SAXException Any SAX exception, possibly
* wrapping another exception.
* @see #startDocument
*/
public void endDocument()
throws SAXException;
/**
* Begin the scope of a prefix-URI Namespace mapping.
*
* <p>The information from this event is not necessary for
* normal Namespace processing: the SAX XML reader will
* automatically replace prefixes for element and attribute
* names when the <code>http://xml.org/sax/features/namespaces</code>
* feature is <var>true</var> (the default).</p>
*
* <p>There are cases, however, when applications need to
* use prefixes in character data or in attribute values,
* where they cannot safely be expanded automatically; the
* start/endPrefixMapping event supplies the information
* to the application to expand prefixes in those contexts
* itself, if necessary.</p>
*
* <p>Note that start/endPrefixMapping events are not
* guaranteed to be properly nested relative to each-other:
* all startPrefixMapping events will occur before the
* corresponding {@link #startElement startElement} event,
* and all {@link #endPrefixMapping endPrefixMapping}
* events will occur after the corresponding {@link #endElement
* endElement} event, but their order is not otherwise
* guaranteed.</p>
*
* <p>There should never be start/endPrefixMapping events for the
* "xml" prefix, since it is predeclared and immutable.</p>
*
* @param prefix The Namespace prefix being declared.
* @param uri The Namespace URI the prefix is mapped to.
* @exception SAXException The client may throw
* an exception during processing.
* @see #endPrefixMapping
* @see #startElement
*/
public void startPrefixMapping(String prefix, String uri)
throws SAXException;
/**
* End the scope of a prefix-URI mapping.
*
* <p>See {@link #startPrefixMapping startPrefixMapping} for
* details. This event will always occur after the corresponding
* {@link #endElement endElement} event, but the order of
* {@link #endPrefixMapping endPrefixMapping} events is not otherwise
* guaranteed.</p>
*
* @param prefix The prefix that was being mapping.
* @exception SAXException The client may throw
* an exception during processing.
* @see #startPrefixMapping
* @see #endElement
*/
public void endPrefixMapping(String prefix)
throws SAXException;
/**
* Receive notification of the beginning of an element.
*
* <p>The Parser will invoke this method at the beginning of every
* element in the XML document; there will be a corresponding
* {@link #endElement endElement} event for every startElement event
* (even when the element is empty). All of the element's content will be
* reported, in order, before the corresponding endElement
* event.</p>
*
* <p>This event allows up to three name components for each
* element:</p>
*
* <ol>
* <li>the Namespace URI;</li>
* <li>the local name; and</li>
* <li>the qualified (prefixed) name.</li>
* </ol>
*
* <p>Any or all of these may be provided, depending on the
* values of the <var>http://xml.org/sax/features/namespaces</var>
* and the <var>http://xml.org/sax/features/namespace-prefixes</var>
* properties:</p>
*
* <ul>
* <li>the Namespace URI and local name are required when
* the namespaces property is <var>true</var> (the default), and are
* optional when the namespaces property is <var>false</var> (if one is
* specified, both must be);</li>
* <li>the qualified name is required when the namespace-prefixes property
* is <var>true</var>, and is optional when the namespace-prefixes property
* is <var>false</var> (the default).</li>
* </ul>
*
* <p>Note that the attribute list provided will contain only
* attributes with explicit values (specified or defaulted):
* #IMPLIED attributes will be omitted. The attribute list
* will contain attributes used for Namespace declarations
* (xmlns* attributes) only if the
* <code>http://xml.org/sax/features/namespace-prefixes</code>
* property is true (it is false by default, and support for a
* true value is optional).</p>
*
* @param uri The Namespace URI, or the empty string if the
* element has no Namespace URI or if Namespace
* processing is not being performed.
* @param localName The local name (without prefix), or the
* empty string if Namespace processing is not being
* performed.
* @param qName The qualified name (with prefix), or the
* empty string if qualified names are not available.
* @param atts The attributes attached to the element. If
* there are no attributes, it shall be an empty
* Attributes object.
* @exception SAXException Any SAX exception, possibly
* wrapping another exception.
* @see #endElement
* @see Attributes
*/
public void startElement(String namespaceURI, String localName,
String qName, Attributes atts)
throws SAXException;
/**
* Receive notification of the end of an element.
*
* <p>The SAX parser will invoke this method at the end of every
* element in the XML document; there will be a corresponding
* {@link #startElement startElement} event for every endElement
* event (even when the element is empty).</p>
*
* <p>For information on the names, see startElement.</p>
*
* @param uri The Namespace URI, or the empty string if the
* element has no Namespace URI or if Namespace
* processing is not being performed.
* @param localName The local name (without prefix), or the
* empty string if Namespace processing is not being
* performed.
* @param qName The qualified XML 1.0 name (with prefix), or the
* empty string if qualified names are not available.
* @exception SAXException Any SAX exception, possibly
* wrapping another exception.
*/
public void endElement(String namespaceURI, String localName,
String qName)
throws SAXException;
/**
* Receive notification of character data.
*
* <p>The Parser will call this method to report each chunk of
* character data. SAX parsers may return all contiguous character
* data in a single chunk, or they may split it into several
* chunks; however, all of the characters in any single event
* must come from the same external entity so that the Locator
* provides useful information.</p>
*
* <p>The application must not attempt to read from the array
* outside of the specified range.</p>
*
* <p>Note that some parsers will report whitespace in element
* content using the {@link #ignorableWhitespace ignorableWhitespace}
* method rather than this one (validating parsers <em>must</em>
* do so).</p>
*
* @param ch The characters from the XML document.
* @param start The start position in the array.
* @param length The number of characters to read from the array.
* @exception SAXException Any SAX exception, possibly
* wrapping another exception.
* @see #ignorableWhitespace
* @see Locator
*/
public void characters(char ch[], int start, int length)
throws SAXException;
/**
* Receive notification of ignorable whitespace in element content.
*
* <p>Validating Parsers must use this method to report each chunk
* of whitespace in element content (see the W3C XML 1.0 recommendation,
* section 2.10): non-validating parsers may also use this method
* if they are capable of parsing and using content models.</p>
*
* <p>SAX parsers may return all contiguous whitespace in a single
* chunk, or they may split it into several chunks; however, all of
* the characters in any single event must come from the same
* external entity, so that the Locator provides useful
* information.</p>
*
* <p>The application must not attempt to read from the array
* outside of the specified range.</p>
*
* @param ch The characters from the XML document.
* @param start The start position in the array.
* @param length The number of characters to read from the array.
* @exception SAXException Any SAX exception, possibly
* wrapping another exception.
* @see #characters
*/
public void ignorableWhitespace(char ch[], int start, int length)
throws SAXException;
/**
* Receive notification of a processing instruction.
*
* <p>The Parser will invoke this method once for each processing
* instruction found: note that processing instructions may occur
* before or after the main document element.</p>
*
* <p>A SAX parser must never report an XML declaration (XML 1.0,
* section 2.8) or a text declaration (XML 1.0, section 4.3.1)
* using this method.</p>
*
* @param target The processing instruction target.
* @param data The processing instruction data, or null if
* none was supplied. The data does not include any
* whitespace separating it from the target.
* @exception SAXException Any SAX exception, possibly
* wrapping another exception.
*/
public void processingInstruction(String target, String data)
throws SAXException;
/**
* Receive notification of a skipped entity.
*
* <p>The Parser will invoke this method once for each entity
* skipped. Non-validating processors may skip entities if they
* have not seen the declarations (because, for example, the
* entity was declared in an external DTD subset). All processors
* may skip external entities, depending on the values of the
* <code>http://xml.org/sax/features/external-general-entities</code>
* and the
* <code>http://xml.org/sax/features/external-parameter-entities</code>
* properties.</p>
*
* @param name The name of the skipped entity. If it is a
* parameter entity, the name will begin with '%', and if
* it is the external DTD subset, it will be the string
* "[dtd]".
* @exception SAXException Any SAX exception, possibly
* wrapping another exception.
*/
public void skippedEntity(String name)
throws SAXException;
}
// end of ContentHandler.java