* This module, both source code and documentation, is in the * Public Domain, and comes with NO WARRANTY. * See http://www.saxproject.org * for further information. ** *
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 org.xml.sax.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.
* *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.
* *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).
* *Implementors should note that there is also a
* ContentHandler class in the java.net
* package; that means that it's probably a bad idea to do
import java.net.*; * import org.xml.sax.*; ** *
In fact, "import ...*" is usually a sign of sloppy programming * anyway, so the user should consider this a feature rather than a * bug.
* * @since SAX 2.0 * @author David Megginson * @see org.xml.sax.XMLReader * @see org.xml.sax.DTDHandler * @see org.xml.sax.ErrorHandler */ public interface ContentHandler { /** * Receive an object for locating the origin of SAX document events. * *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.
* *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.
* *Note that the locator will return correct information only * during the invocation SAX event callbacks after * {@link #startDocument startDocument} returns and before * {@link #endDocument endDocument} is called. The * application should not attempt to use it at any other time.
* * @param locator an object that can return the location of * any SAX document event * @see org.xml.sax.Locator */ public void setDocumentLocator (Locator locator); /** * Receive notification of the beginning of a document. * *The SAX parser will invoke this method only once, before any * other event callbacks (except for {@link #setDocumentLocator * setDocumentLocator}).
* * @throws org.xml.sax.SAXException any SAX exception, possibly * wrapping another exception * @see #endDocument */ public void startDocument () throws SAXException; /** * Receive notification of the end of a document. * *There is an apparent contradiction between the * documentation for this method and the documentation for {@link * org.xml.sax.ErrorHandler#fatalError}. Until this ambiguity is * resolved in a future major release, clients should make no * assumptions about whether endDocument() will or will not be * invoked when the parser has reported a fatalError() or thrown * an exception.
* *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.
* * @throws org.xml.sax.SAXException any SAX exception, possibly * wrapping another exception * @see #startDocument */ public void endDocument() throws SAXException; /** * Begin the scope of a prefix-URI Namespace mapping. * *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 http://xml.org/sax/features/namespaces
* feature is true (the default).
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.
* *Note that start/endPrefixMapping events are not * guaranteed to be properly nested relative to each other: * all startPrefixMapping events will occur immediately before the * corresponding {@link #startElement startElement} event, * and all {@link #endPrefixMapping endPrefixMapping} * events will occur immediately after the corresponding * {@link #endElement endElement} event, * but their order is not otherwise * guaranteed.
* *There should never be start/endPrefixMapping events for the * "xml" prefix, since it is predeclared and immutable.
* * @param prefix the Namespace prefix being declared. * An empty string is used for the default element namespace, * which has no prefix. * @param uri the Namespace URI the prefix is mapped to * @throws org.xml.sax.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. * *See {@link #startPrefixMapping startPrefixMapping} for * details. These events will always occur immediately after the * corresponding {@link #endElement endElement} event, but the order of * {@link #endPrefixMapping endPrefixMapping} events is not otherwise * guaranteed.
* * @param prefix the prefix that was being mapped. * This is the empty string when a default mapping scope ends. * @throws org.xml.sax.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. * *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.
* *This event allows up to three name components for each * element:
* *Any or all of these may be provided, depending on the * values of the http://xml.org/sax/features/namespaces * and the http://xml.org/sax/features/namespace-prefixes * properties:
* *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
* http://xml.org/sax/features/namespace-prefixes
* property is true (it is false by default, and support for a
* true value is optional).
Like {@link #characters characters()}, attribute values may have
* characters that need more than one char value.
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).
* *For information on the names, see startElement.
* * @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 name (with prefix), or the * empty string if qualified names are not available * @throws org.xml.sax.SAXException any SAX exception, possibly * wrapping another exception */ public void endElement (String uri, String localName, String qName) throws SAXException; /** * Receive notification of character data. * *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.
* *The application must not attempt to read from the array * outside of the specified range.
* *Individual characters may consist of more than one Java
* char value. There are two important cases where this
* happens, because characters can't be represented in just sixteen bits.
* In one case, characters are represented in a Surrogate Pair,
* using two special Unicode values. Such characters are in the so-called
* "Astral Planes", with a code point above U+FFFF. A second case involves
* composite characters, such as a base character combining with one or
* more accent characters.
Your code should not assume that algorithms using
* char-at-a-time idioms will be working in character
* units; in some cases they will split characters. This is relevant
* wherever XML permits arbitrary characters, such as attribute values,
* processing instruction data, and comments as well as in data reported
* from this method. It's also generally relevant whenever Java code
* manipulates internationalized text; the issue isn't unique to XML.
Note that some parsers will report whitespace in element * content using the {@link #ignorableWhitespace ignorableWhitespace} * method rather than this one (validating parsers must * do so).
* * @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 * @throws org.xml.sax.SAXException any SAX exception, possibly * wrapping another exception * @see #ignorableWhitespace * @see org.xml.sax.Locator */ public void characters (char ch[], int start, int length) throws SAXException; /** * Receive notification of ignorable whitespace in element content. * *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.
* *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.
* *The application must not attempt to read from the array * outside of the specified range.
* * @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 * @throws org.xml.sax.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. * *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.
* *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.
* *Like {@link #characters characters()}, processing instruction
* data may have characters that need more than one char
* value.
The Parser will invoke this method each time the entity is
* 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
* http://xml.org/sax/features/external-general-entities
* and the
* http://xml.org/sax/features/external-parameter-entities
* properties.