ContentHandlerpublic interface ContentHandler Receive notification of the logical content of a document.
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. |
| Methods Summary |
|---|
| public void | characters(char[] ch, int start, int length)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).
| | public void | endDocument()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.
| | public void | endElement(java.lang.String uri, java.lang.String localName, java.lang.String qName)Receive notification of the end of an element.
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.
| | public void | endPrefixMapping(java.lang.String prefix)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.
| | public void | ignorableWhitespace(char[] ch, int start, int length)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.
| | public void | processingInstruction(java.lang.String target, java.lang.String data)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.
| | public void | setDocumentLocator(org.xml.sax.Locator locator)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.
| | public void | skippedEntity(java.lang.String name)Receive notification of a skipped entity.
This is not called for entity references within markup constructs
such as element start tags or markup declarations. (The XML
recommendation requires reporting skipped external entities.
SAX also reports internal entity expansion/non-expansion, except
within markup constructs.)
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.
| | public void | startDocument()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}).
| | public void | startElement(java.lang.String uri, java.lang.String localName, java.lang.String qName, org.xml.sax.Attributes atts)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:
- the Namespace URI;
- the local name; and
- the qualified (prefixed) name.
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:
- the Namespace URI and local name are required when
the namespaces property is true (the default), and are
optional when the namespaces property is false (if one is
specified, both must be);
- the qualified name is required when the namespace-prefixes property
is true, and is optional when the namespace-prefixes property
is false (the default).
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.
| | public void | startPrefixMapping(java.lang.String prefix, java.lang.String uri)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.
|
|
