org.codehaus.plexus.util.xml.pull
public interface XmlPullParser
There are following different kinds of parser depending on which features are set:
There are two key methods: next() and nextToken(). While next() provides access to high level parsing events, nextToken() allows access to lower level tokens.
The current event state of the parser can be determined by calling the getEventType() method. Initially, the parser is in the START_DOCUMENT state.
The method next() advances the parser to the next event. The int value returned from next determines the current parser state and is identical to the value returned from following calls to getEventType ().
The following event types are seen by next()
after first next() or nextToken() (or any other next*() method) is called user application can obtain XML version, standalone and encoding from XML declaration in following ways:
import java.io.IOException; import java.io.StringReader; import org.xmlpull.v1.XmlPullParser; import org.xmlpull.v1.XmlPullParserException.html; import org.xmlpull.v1.XmlPullParserFactory; public class SimpleXmlPullApp { public static void main (String args[]) throws XmlPullParserException, IOException { XmlPullParserFactory factory = XmlPullParserFactory.newInstance(); factory.setNamespaceAware(true); XmlPullParser xpp = factory.newPullParser(); xpp.setInput( new StringReader ( "<foo>Hello World!</foo>" ) ); int eventType = xpp.getEventType(); while (eventType != xpp.END_DOCUMENT) { if(eventType == xpp.START_DOCUMENT) { System.out.println("Start document"); } else if(eventType == xpp.END_DOCUMENT) { System.out.println("End document"); } else if(eventType == xpp.START_TAG) { System.out.println("Start tag "+xpp.getName()); } else if(eventType == xpp.END_TAG) { System.out.println("End tag "+xpp.getName()); } else if(eventType == xpp.TEXT) { System.out.println("Text "+xpp.getText()); } eventType = xpp.next(); } } }
The above example will generate the following output:
Start document Start tag foo Text Hello World! End tag foo
For more details on API usage, please refer to the quick Introduction available at http://www.xmlpull.org
See Also: XmlPullParser XmlPullParser XmlPullParser XmlPullParser XmlPullParser XmlPullParser XmlPullParser FEATURE_PROCESS_DOCDECL FEATURE_VALIDATION START_DOCUMENT START_TAG TEXT END_TAG END_DOCUMENT
Field Summary | |
---|---|
int | CDSECT
A CDATA sections was just read;
this token is available only from calls to nextToken().
|
int | COMMENT
An XML comment was just read. |
int | DOCDECL
An XML document type declaration was just read. |
int | END_DOCUMENT
Logical end of the xml document. |
int | END_TAG
Returned from getEventType(), next(), or
nextToken() when an end tag was read.
|
int | ENTITY_REF
An entity reference was just read;
this token is available from nextToken()
only. |
String | FEATURE_PROCESS_DOCDECL
This feature determines whether the document declaration
is processed. |
String | FEATURE_PROCESS_NAMESPACES
This feature determines whether the parser processes
namespaces. |
String | FEATURE_REPORT_NAMESPACE_ATTRIBUTES
This feature determines whether namespace attributes are
exposed via the attribute access methods. |
String | FEATURE_VALIDATION
If this feature is activated, all validation errors as
defined in the XML 1.0 sepcification are reported.
|
int | IGNORABLE_WHITESPACE
Ignorable whitespace was just read.
|
String | NO_NAMESPACE This constant represents the default namespace (empty string "") |
int | PROCESSING_INSTRUCTION
An XML processing instruction declaration was just read. |
int | START_DOCUMENT
Signalize that parser is at the very beginning of the document
and nothing was read yet.
|
int | START_TAG
Returned from getEventType(),
next(), nextToken() when
a start tag was read.
|
int | TEXT
Character data was read and will is available by calling getText().
|
String[] | TYPES
This array can be used to convert the event type integer constants
such as START_TAG or TEXT to
to a string. |
Method Summary | |
---|---|
void | defineEntityReplacementText(String entityName, String replacementText)
Set new value for entity replacement text as defined in
XML 1.0 Section 4.5
Construction of Internal Entity Replacement Text.
|
int | getAttributeCount()
Returns the number of attributes of the current start tag, or
-1 if the current event type is not START_TAG
|
String | getAttributeName(int index)
Returns the local name of the specified attribute
if namespaces are enabled or just attribute name if namespaces are disabled.
|
String | getAttributeNamespace(int index)
Returns the namespace URI of the attribute
with the given index (starts from 0).
|
String | getAttributePrefix(int index)
Returns the prefix of the specified attribute
Returns null if the element has no prefix.
|
String | getAttributeType(int index)
Returns the type of the specified attribute
If parser is non-validating it MUST return CDATA.
|
String | getAttributeValue(int index)
Returns the given attributes value.
|
String | getAttributeValue(String namespace, String name)
Returns the attributes value identified by namespace URI and namespace localName.
|
int | getColumnNumber()
Returns the current column number, starting from 0.
|
int | getDepth()
Returns the current depth of the element.
|
int | getEventType()
Returns the type of the current event (START_TAG, END_TAG, TEXT, etc.)
|
boolean | getFeature(String name)
Returns the current value of the given feature.
|
String | getInputEncoding()
Returns the input encoding if known, null otherwise.
|
int | getLineNumber()
Returns the current line number, starting from 1.
|
String | getName()
For START_TAG or END_TAG events, the (local) name of the current
element is returned when namespaces are enabled. |
String | getNamespace(String prefix)
Returns the URI corresponding to the given prefix,
depending on current state of the parser.
|
String | getNamespace()
Returns the namespace URI of the current element.
|
int | getNamespaceCount(int depth)
Returns the numbers of elements in the namespace stack for the given
depth.
|
String | getNamespacePrefix(int pos)
Returns the namespace prefixe for the given position
in the namespace stack.
|
String | getNamespaceUri(int pos)
Returns the namespace URI for the given position in the
namespace stack
If the position is out of range, an exception is thrown.
|
String | getPositionDescription()
Returns a short text describing the current parser state, including
the position, a
description of the current event and the data source if known.
|
String | getPrefix()
Returns the prefix of the current element.
|
Object | getProperty(String name)
Look up the value of a property.
|
String | getText()
Returns the text content of the current event as String.
|
char[] | getTextCharacters(int[] holderForStartAndLength)
Returns the buffer that contains the text of the current event,
as well as the start offset and length relevant for the current
event. |
boolean | isAttributeDefault(int index)
Returns if the specified attribute was not in input was declared in XML.
|
boolean | isEmptyElementTag()
Returns true if the current event is START_TAG and the tag
is degenerated
(e.g. |
boolean | isWhitespace()
Checks whether the current TEXT event contains only whitespace
characters.
|
int | next()
Get next parsing event - element content wil be coalesced and only one
TEXT event must be returned for whole element content
(comments and processing instructions will be ignored and emtity references
must be expanded or exception mus be thrown if entity reerence can not be exapnded).
|
int | nextTag()
Call next() and return event if it is START_TAG or END_TAG
otherwise throw an exception.
|
String | nextText()
If current event is START_TAG then if next element is TEXT then element content is returned
or if next event is END_TAG then empty string is returned, otherwise exception is thrown.
|
int | nextToken()
This method works similarly to next() but will expose
additional event types (COMMENT, CDSECT, DOCDECL, ENTITY_REF, PROCESSING_INSTRUCTION, or
IGNORABLE_WHITESPACE) if they are available in input.
|
void | require(int type, String namespace, String name)
Test if the current event is of the given type and if the
namespace and name do match. null will match any namespace
and any name. |
void | setFeature(String name, boolean state)
Use this call to change the general behaviour of the parser,
such as namespace processing or doctype declaration handling.
|
void | setInput(Reader in)
Set the input source for parser to the given reader and
resets the parser. |
void | setInput(InputStream inputStream, String inputEncoding)
Sets the input stream the parser is going to process.
|
void | setProperty(String name, Object value)
Set the value of a property.
|
See Also: XmlPullParser XmlPullParser
See Also: XmlPullParser XmlPullParser
See Also: XmlPullParser XmlPullParser
NOTE: calling again next() or nextToken() will result in exception being thrown.
See Also: XmlPullParser XmlPullParser
See Also: XmlPullParser XmlPullParser XmlPullParser XmlPullParser XmlPullParser FEATURE_PROCESS_NAMESPACES
See Also: XmlPullParser XmlPullParser
Please note: If the document type declaration was ignored, entity references may cause exceptions later in the parsing process. The default value of this feature is false. It cannot be changed during parsing.
See Also: XmlPullParser XmlPullParser
NOTE: The value can not be changed during parsing an must be set before parsing.
See Also: XmlPullParser XmlPullParser
See Also: XmlPullParser XmlPullParser
Please Note: This feature can not be changed during parsing. The default value is false.
See Also: XmlPullParser XmlPullParser
NOTE: this is different from calling the isWhitespace() method, since text content may be whitespace but not ignorable. Ignorable whitespace is skipped by next() automatically; this event type is never returned from next().
See Also: XmlPullParser XmlPullParser
See Also: XmlPullParser XmlPullParser
See Also: XmlPullParser XmlPullParser
See Also: XmlPullParser XmlPullParser XmlPullParser XmlPullParser XmlPullParser XmlPullParser XmlPullParser XmlPullParser XmlPullParser FEATURE_PROCESS_NAMESPACES
Please note: next() will accumulate multiple events into one TEXT event, skipping IGNORABLE_WHITESPACE, PROCESSING_INSTRUCTION and COMMENT events, In contrast, nextToken() will stop reading text when any other event is observed. Also, when the state was reached by calling next(), the text value will be normalized, whereas getText() will return unnormalized content in the case of nextToken(). This allows an exact roundtrip without changing line ends when examining low level events, whereas for high level applications the text is normalized appropriately.
See Also: XmlPullParser XmlPullParser XmlPullParser
The motivation for this function is to allow very small implementations of XMLPULL that will work in J2ME environments. Though these implementations may not be able to process the document type declaration, they still can work with known DTDs by using this function.
Please notes: The given value is used literally as replacement text and it corresponds to declaring entity in DTD that has all special characters escaped: left angle bracket is replaced with <, ampersnad with & and so on.
Note: The given value is the literal replacement text and must not contain any other entity reference (if it contains any entity reference there will be no further replacement).
Note: The list of pre-defined entity names will always contain standard XML entities such as amp (&), lt (<), gt (>), quot ("), and apos ('). Those cannot be redefined by this method!
See Also: XmlPullParser FEATURE_PROCESS_DOCDECL FEATURE_VALIDATION
See Also: XmlPullParser XmlPullParser XmlPullParser XmlPullParser
Parameters: index zero based index of attribute
Returns: attribute name (null is never returned)
NOTE: if FEATURE_REPORT_NAMESPACE_ATTRIBUTES is set then namespace attributes (xmlns:ns='...') must be reported with namespace http://www.w3.org/2000/xmlns/ (visit this URL for description!). The default namespace attribute (xmlns="...") will be reported with empty namespace.
NOTE:The xml prefix is bound as defined in Namespaces in XML specification to "http://www.w3.org/XML/1998/namespace".
Parameters: index zero based index of attribute
Returns: attribute namespace, empty string ("") is returned if namesapces processing is not enabled or namespaces processing is enabled but attribute has no namespace (it has no prefix).
Parameters: index zero based index of attribute
Returns: attribute prefix or null if namespaces processing is not enabled.
Parameters: index zero based index of attribute
Returns: attribute type (null is never returned)
NOTE: attribute value must be normalized (including entity replacement text if PROCESS_DOCDECL is false) as described in XML 1.0 section 3.3.3 Attribute-Value Normalization
Parameters: index zero based index of attribute
Returns: value of attribute (null is never returned)
See Also: XmlPullParser
NOTE: attribute value must be normalized (including entity replacement text if PROCESS_DOCDECL is false) as described in XML 1.0 section 3.3.3 Attribute-Value Normalization
Parameters: namespace Namespace of the attribute if namespaces are enabled otherwise must be null name If namespaces enabled local name of attribute otherwise just attribute name
Returns: value of attribute or null if attribute with given name does not exist
See Also: XmlPullParser
Returns: current column number or -1 if unknown.
<!-- outside --> 0 <root> 1 sometext 1 <foobar> 2 </foobar> 2 </root> 1 <!-- outside --> 0
Please note: unknown features are always returned as false.
Parameters: name The name of feature to be retrieved.
Returns: The value of the feature.
Throws: IllegalArgumentException if string the feature name is null
Returns: current line number or -1 if unknown.
Please note: To reconstruct the raw element name when namespaces are enabled and the prefix is not null, you will need to add the prefix and a colon to localName..
If the prefix was not declared in the current scope, null is returned. The default namespace is included in the namespace table and is available via getNamespace (null).
This method is a convenience method for
for (int i = getNamespaceCount(getDepth ())-1; i >= 0; i--) { if (getNamespacePrefix(i).equals( prefix )) { return getNamespaceUri(i); } } return null;
Please note: parser implementations may provide more efifcient lookup, e.g. using a Hashtable. The 'xml' prefix is bound to "http://www.w3.org/XML/1998/namespace", as defined in the Namespaces in XML specification. Analogous, the 'xmlns' prefix is resolved to http://www.w3.org/2000/xmlns/
See Also: XmlPullParser XmlPullParser XmlPullParser
NOTE: when parser is on END_TAG then it is allowed to call this function with getDepth()+1 argument to retrieve position of namespace prefixes and URIs that were declared on corresponding START_TAG.
NOTE: to retrieve lsit of namespaces declared in current element:
XmlPullParser pp = ... int nsStart = pp.getNamespaceCount(pp.getDepth()-1); int nsEnd = pp.getNamespaceCount(pp.getDepth()); for (int i = nsStart; i < nsEnd; i++) { String prefix = pp.getNamespacePrefix(i); String ns = pp.getNamespaceUri(i); // ... }
See Also: XmlPullParser XmlPullParser getNamespace getNamespace
Please note: when the parser is on an END_TAG, namespace prefixes that were declared in the corresponding START_TAG are still accessible although they are no longer in scope.
NOTE: when parser is on END_TAG then namespace prefixes that were declared in corresponding START_TAG are still accessible even though they are not in scope
NOTE: unknown properties are always returned as null.
Parameters: name The name of property to be retrieved.
Returns: The value of named property.
NOTE: in case of ENTITY_REF, this method returns the entity replacement text (or null if not available). This is the only case where getText() and getTextCharacters() return different values.
See Also: XmlPullParser XmlPullParser XmlPullParser
Please note: this buffer must not be modified and its content MAY change after a call to next() or nextToken(). This method will always return the same value as getText(), except for ENTITY_REF. In the case of ENTITY ref, getText() returns the replacement text and this method returns the actual input buffer containing the entity name. If getText() returns null, this method returns null as well and the values returned in the holder array MUST be -1 (both start and length).
Parameters: holderForStartAndLength Must hold an 2-element int array into which the start offset and length values will be written.
Returns: char buffer that contains the text of the current event (null if the current event has no text associated).
See Also: XmlPullParser XmlPullParser XmlPullParser
Parameters: index zero based index of attribute
Returns: false if attribute was in input
NOTE: if the parser is not on START_TAG, an exception will be thrown.
Please note: non-validating parsers are not able to distinguish whitespace and ignorable whitespace, except from whitespace outside the root element. Ignorable whitespace is reported as separate event, which is exposed via nextToken only.
NOTE: empty element (such as <tag/>) will be reported with two separate events: START_TAG, END_TAG - it must be so to preserve parsing equivalency of empty element to <tag></tag>. (see isEmptyElementTag ())
See Also: XmlPullParser START_TAG TEXT END_TAG END_DOCUMENT
essentially it does this
int eventType = next(); if(eventType == TEXT && isWhitespace()) { // skip whitespace eventType = next(); } if (eventType != START_TAG && eventType != END_TAG) { throw new XmlPullParserException("expected start or end tag", this, null); } return eventType;
The motivation for this function is to allow to parse consistently both empty elements and elements that has non empty content, for example for input:
p.nextTag() p.requireEvent(p.START_TAG, "", "tag"); String content = p.nextText(); p.requireEvent(p.END_TAG, "", "tag");This function together with nextTag make it very easy to parse XML that has no mixed content.
Essentially it does this
if(getEventType() != START_TAG) { throw new XmlPullParserException( "parser must be on START_TAG to read next text", this, null); } int eventType = next(); if(eventType == TEXT) { String result = getText(); eventType = next(); if(eventType != END_TAG) { throw new XmlPullParserException( "event TEXT it must be immediately followed by END_TAG", this, null); } return result; } else if(eventType == END_TAG) { return ""; } else { throw new XmlPullParserException( "parser must be on START_TAG or TEXT to read text", this, null); }
If special feature FEATURE_XML_ROUNDTRIP (identified by URI: http://xmlpull.org/v1/doc/features.html#xml-roundtrip) is enabled it is possible to do XML document round trip ie. reproduce exectly on output the XML input using getText(): returned content is always unnormalized (exactly as in input). Otherwise returned content is end-of-line normalized as described XML 1.0 End-of-Line Handling and. Also when this feature is enabled exact content of START_TAG, END_TAG, DOCDECL and PROCESSING_INSTRUCTION is available.
Here is the list of tokens that can be returned from nextToken() and what getText() and getTextCharacters() returns:
" titlepage SYSTEM "http://www.foo.bar/dtds/typo.dtd" [<!ENTITY % active.links "INCLUDE">]"
for input document that contained:
<!DOCTYPE titlepage SYSTEM "http://www.foo.bar/dtds/typo.dtd" [<!ENTITY % active.links "INCLUDE">]>otherwise if FEATURE_XML_ROUNDTRIP is false and PROCESS_DOCDECL is true then what is returned is undefined (it may be even null)
NOTE: there is no gurantee that there will only one TEXT or IGNORABLE_WHITESPACE event from nextToken() as parser may chose to deliver element content in multiple tokens (dividing element content into chunks)
NOTE: whether returned text of token is end-of-line normalized is depending on FEATURE_XML_ROUNDTRIP.
NOTE: XMLDecl (<?xml ...?>) is not reported but its content is available through optional properties (see class description above).
See Also: XmlPullParser START_TAG TEXT END_TAG END_DOCUMENT COMMENT DOCDECL PROCESSING_INSTRUCTION ENTITY_REF IGNORABLE_WHITESPACE
Essentially it does this
if (type != getEventType() || (namespace != null && !namespace.equals( getNamespace () ) ) || (name != null && !name.equals( getName() ) ) ) throw new XmlPullParserException( "expected "+ TYPES[ type ]+getPositionDescription());
Example: call setFeature(FEATURE_PROCESS_NAMESPACES, true) in order to switch on namespace processing. The initial settings correspond to the properties requested from the XML Pull Parser factory. If none were requested, all feautures are deactivated by default.
Throws: XmlPullParserException If the feature is not supported or can not be set IllegalArgumentException If string with the feature name is null
NOTE: If an input encoding string is passed, it MUST be used. Otherwise, if inputEncoding is null, the parser SHOULD try to determine input encoding following XML 1.0 specification (see below). If encoding detection is supported then following feature http://xmlpull.org/v1/doc/features.html#detect-encoding MUST be true amd otherwise it must be false
Parameters: inputStream contains a raw byte input stream of possibly unknown encoding (when inputEncoding is null). inputEncoding if not null it MUST be used as encoding for inputStream
Throws: XmlPullParserException If the property is not supported or can not be set IllegalArgumentException If string with the property name is null