XMLStreamConstants
StreamReaderDelegate
public interface XMLStreamReader extends XMLStreamConstants
The XMLStreamReader is designed to iterate over XML using next() and hasNext(). The data can be accessed using methods such as getEventType(), getNamespaceURI(), getLocalName() and getText();
An XMLStreamReader instance is created with an initial event type START_DOCUMENT. At any moment in time, it has a current event that the methods of the interface access and may load the next event through the next()
method. The current event type can be determined by getEventType()
, and the next returned by the next()
method.
Parsing events are defined as the XML Declaration, a DTD, start tag, character data, white space, end tag, comment, or processing instruction. An attribute or namespace event may be encountered at the root level of a document as the result of a query operation.
For XML 1.0 compliance an XML processor must pass the identifiers of declared unparsed entities, notation declarations and their associated identifiers to the application. This information is provided through the property API on this interface. The following two properties allow access to this information: javax.xml.stream.notations and javax.xml.stream.entities. When the current event is a DTD the following call will return a list of Notations List l = (List) getProperty("javax.xml.stream.notations");
The following call will return a list of entity declarations: List l = (List) getProperty("javax.xml.stream.entities");
These properties can only be accessed during a DTD event and are defined to return null if the information is not available.
The following table describes which methods are valid in what state. If a method is called in an invalid state the method will throw a java.lang.IllegalStateException.
Event Type | Valid Methods |
---|---|
All States | getProperty(), hasNext(), require(), close(), getNamespaceURI(), isStartElement(), isEndElement(), isCharacters(), isWhiteSpace(), getNamespaceContext(), getEventType(), getLocation(), hasText(), hasName() |
START_ELEMENT | next(), getName(), getLocalName(), hasName(), getPrefix(), getAttributeXXX(), isAttributeSpecified(), getNamespaceXXX(), getElementText(), nextTag() |
ATTRIBUTE | next(), nextTag() getAttributeXXX(), isAttributeSpecified(), |
NAMESPACE | next(), nextTag() getNamespaceXXX() |
END_ELEMENT | next(), getName(), getLocalName(), hasName(), getPrefix(), getNamespaceXXX(), nextTag() |
CHARACTERS | next(), getTextXXX(), nextTag() |
CDATA | next(), getTextXXX(), nextTag() |
COMMENT | next(), getTextXXX(), nextTag() |
SPACE | next(), getTextXXX(), nextTag() |
START_DOCUMENT | next(), getEncoding(), getVersion(), isStandalone(), standaloneSet(), getCharacterEncodingScheme(), nextTag() |
END_DOCUMENT | close() |
PROCESSING_INSTRUCTION | next(), getPITarget(), getPIData(), nextTag() |
ENTITY_REFERENCE | next(), getLocalName(), getText(), nextTag() |
DTD | next(), getText(), nextTag() |
ATTRIBUTE, CDATA, CHARACTERS, COMMENT, DTD, END_DOCUMENT, END_ELEMENT, ENTITY_DECLARATION, ENTITY_REFERENCE, NAMESPACE, NOTATION_DECLARATION, PROCESSING_INSTRUCTION, SPACE, START_DOCUMENT, START_ELEMENT
Modifier and Type | Method | Description |
---|---|---|
void |
close() |
Frees any resources associated with this Reader. |
int |
getAttributeCount() |
Returns the count of attributes on this START_ELEMENT, this method is only valid on a START_ELEMENT or ATTRIBUTE. |
String |
getAttributeLocalName |
Returns the localName of the attribute at the provided index |
QName |
getAttributeName |
Returns the qname of the attribute at the provided index |
String |
getAttributeNamespace |
Returns the namespace of the attribute at the provided index |
String |
getAttributePrefix |
Returns the prefix of this attribute at the provided index |
String |
getAttributeType |
Returns the XML type of the attribute at the provided index |
String |
getAttributeValue |
Returns the value of the attribute at the index |
String |
getAttributeValue |
Returns the normalized attribute value of the attribute with the namespace and localName If the namespaceURI is null the namespace is not checked for equality |
String |
getCharacterEncodingScheme() |
Returns the character encoding declared on the xml declaration Returns null if none was declared |
String |
getElementText() |
Reads the content of a text-only element, an exception is thrown if this is not a text-only element. |
String |
getEncoding() |
Return input encoding if known or null if unknown. |
int |
getEventType() |
Returns an integer code that indicates the type of the event the cursor is pointing to. |
String |
getLocalName() |
Returns the (local) name of the current event. |
Location |
getLocation() |
Return the current location of the processor. |
QName |
getName() |
Returns a QName for the current START_ELEMENT or END_ELEMENT event |
NamespaceContext |
getNamespaceContext() |
Returns a read only namespace context for the current position. |
int |
getNamespaceCount() |
Returns the count of namespaces declared on this START_ELEMENT or END_ELEMENT, this method is only valid on a START_ELEMENT, END_ELEMENT or NAMESPACE. |
String |
getNamespacePrefix |
Returns the prefix for the namespace declared at the index. |
String |
getNamespaceURI() |
If the current event is a START_ELEMENT or END_ELEMENT this method returns the URI of the prefix or the default namespace. |
String |
getNamespaceURI |
Returns the uri for the namespace declared at the index. |
String |
getNamespaceURI |
Return the uri for the given prefix. |
String |
getPIData() |
Get the data section of a processing instruction |
String |
getPITarget() |
Get the target of a processing instruction |
String |
getPrefix() |
Returns the prefix of the current event or null if the event does not have a prefix |
Object |
getProperty |
Get the value of a feature/property from the underlying implementation |
String |
getText() |
Returns the current value of the parse event as a string, this returns the string value of a CHARACTERS event, returns the value of a COMMENT, the replacement value for an ENTITY_REFERENCE, the string value of a CDATA section, the string value for a SPACE event, or the String value of the internal subset of the DTD. |
char[] |
getTextCharacters() |
Returns an array which contains the characters from this event. |
int |
getTextCharacters |
Gets the text associated with a CHARACTERS, SPACE or CDATA event. |
int |
getTextLength() |
Returns the length of the sequence of characters for this Text event within the text character array. |
int |
getTextStart() |
Returns the offset into the text character array where the first character (of this text event) is stored. |
String |
getVersion() |
Get the xml version declared on the xml declaration Returns null if none was declared |
boolean |
hasName() |
returns a boolean indicating whether the current event has a name (is a START_ELEMENT or END_ELEMENT). |
boolean |
hasNext() |
Returns true if there are more parsing events and false if there are no more events. |
boolean |
hasText() |
Return a boolean indicating whether the current event has text. |
boolean |
isAttributeSpecified |
Returns a boolean which indicates if this attribute was created by default |
boolean |
isCharacters() |
Returns true if the cursor points to a character data event |
boolean |
isEndElement() |
Returns true if the cursor points to an end tag (otherwise false) |
boolean |
isStandalone() |
Get the standalone declaration from the xml declaration |
boolean |
isStartElement() |
Returns true if the cursor points to a start tag (otherwise false) |
boolean |
isWhiteSpace() |
Returns true if the cursor points to a character data event that consists of all whitespace |
int |
next() |
Get next parsing event - a processor may return all contiguous character data in a single chunk, or it may split it into several chunks. |
int |
nextTag() |
Skips any white space (isWhiteSpace() returns true), COMMENT, or PROCESSING_INSTRUCTION, until a START_ELEMENT or END_ELEMENT is reached. |
void |
require |
Test if the current event is of the given type and if the namespace and name match the current namespace and name of the current event. |
boolean |
standaloneSet() |
Checks if standalone was set in the document |
Object getProperty(String name) throws IllegalArgumentException
name
- The name of the property, may not be nullIllegalArgumentException
- if name is nullint next() throws XMLStreamException
Given the following XML:
<foo><!--description-->content text<![CDATA[<greeting>Hello>/greeting>]]>other content>/foo>
The behavior of calling next() when being on foo will be:
1- the comment (COMMENT)
2- then the characters section (CHARACTERS)
3- then the CDATA section (another CHARACTERS)
4- then the next characters section (another CHARACTERS)
5- then the END_ELEMENT
NOTE: empty element (such as <tag/>
) will be reported with two separate events: START_ELEMENT, END_ELEMENT - This preserves parsing equivalency of empty element to <tag></tag>
.
NoSuchElementException
- if this is called when hasNext() returns falseXMLStreamException
- if there is an error processing the underlying XML sourcevoid require(int type, String namespaceURI, String localName) throws XMLStreamException
type
- the event typenamespaceURI
- the uri of the event, may be nulllocalName
- the localName of the event, may be nullXMLStreamException
- if the required values are not matched.String getElementText() throws XMLStreamException
if(getEventType() != XMLStreamConstants.START_ELEMENT) { throw new XMLStreamException( "parser must be on START_ELEMENT to read next text", getLocation()); } int eventType = next(); StringBuffer content = new StringBuffer(); while(eventType != XMLStreamConstants.END_ELEMENT) { if(eventType == XMLStreamConstants.CHARACTERS || eventType == XMLStreamConstants.CDATA || eventType == XMLStreamConstants.SPACE || eventType == XMLStreamConstants.ENTITY_REFERENCE) { buf.append(getText()); } else if(eventType == XMLStreamConstants.PROCESSING_INSTRUCTION || eventType == XMLStreamConstants.COMMENT) { // skipping } else if(eventType == XMLStreamConstants.END_DOCUMENT) { throw new XMLStreamException( "unexpected end of document when reading element text content", this); } else if(eventType == XMLStreamConstants.START_ELEMENT) { throw new XMLStreamException( "element text content may not contain START_ELEMENT", getLocation()); } else { throw new XMLStreamException( "Unexpected event type "+eventType, getLocation()); } eventType = next(); } return buf.toString();
XMLStreamException
- if the current event is not a START_ELEMENT or if a non text element is encounteredint nextTag() throws XMLStreamException
int eventType = next();
while((eventType == XMLStreamConstants.CHARACTERS && isWhiteSpace()) // skip whitespace
|| (eventType == XMLStreamConstants.CDATA && isWhiteSpace())
// skip whitespace
|| eventType == XMLStreamConstants.SPACE
|| eventType == XMLStreamConstants.PROCESSING_INSTRUCTION
|| eventType == XMLStreamConstants.COMMENT
) {
eventType = next();
}
if (eventType != XMLStreamConstants.START_ELEMENT && eventType != XMLStreamConstants.END_ELEMENT) {
throw new String XMLStreamException("expected start or end tag", getLocation());
}
return eventType;
XMLStreamException
- if the current event is not white space, PROCESSING_INSTRUCTION, START_ELEMENT or END_ELEMENTNoSuchElementException
- if this is called when hasNext() returns falseboolean hasNext() throws XMLStreamException
XMLStreamException
- if there is a fatal error detecting the next statevoid close() throws XMLStreamException
XMLStreamException
- if there are errors freeing associated resourcesString getNamespaceURI(String prefix)
NOTE:The 'xml' prefix is bound as defined in Namespaces in XML specification to "http://www.w3.org/XML/1998/namespace".
NOTE: The 'xmlns' prefix must be resolved to following namespace http://www.w3.org/2000/xmlns/
prefix
- The prefix to lookup, may not be nullIllegalArgumentException
- if the prefix is nullboolean isStartElement()
boolean isEndElement()
boolean isCharacters()
boolean isWhiteSpace()
String getAttributeValue(String namespaceURI, String localName)
namespaceURI
- the namespace of the attributelocalName
- the local name of the attribute, cannot be nullIllegalStateException
- if this is not a START_ELEMENT or ATTRIBUTEint getAttributeCount()
IllegalStateException
- if this is not a START_ELEMENT or ATTRIBUTEQName getAttributeName(int index)
index
- the position of the attributeIllegalStateException
- if this is not a START_ELEMENT or ATTRIBUTEString getAttributeNamespace(int index)
index
- the position of the attributeIllegalStateException
- if this is not a START_ELEMENT or ATTRIBUTEString getAttributeLocalName(int index)
index
- the position of the attributeIllegalStateException
- if this is not a START_ELEMENT or ATTRIBUTEString getAttributePrefix(int index)
index
- the position of the attributeIllegalStateException
- if this is not a START_ELEMENT or ATTRIBUTEString getAttributeType(int index)
index
- the position of the attributeIllegalStateException
- if this is not a START_ELEMENT or ATTRIBUTEString getAttributeValue(int index)
index
- the position of the attributeIllegalStateException
- if this is not a START_ELEMENT or ATTRIBUTEboolean isAttributeSpecified(int index)
index
- the position of the attributeIllegalStateException
- if this is not a START_ELEMENT or ATTRIBUTEint getNamespaceCount()
IllegalStateException
- if this is not a START_ELEMENT, END_ELEMENT or NAMESPACEString getNamespacePrefix(int index)
index
- the position of the namespace declarationIllegalStateException
- if this is not a START_ELEMENT, END_ELEMENT or NAMESPACEString getNamespaceURI(int index)
index
- the position of the namespace declarationIllegalStateException
- if this is not a START_ELEMENT, END_ELEMENT or NAMESPACENamespaceContext getNamespaceContext()
int getEventType()
XMLStreamConstants.START_DOCUMENT
.String getText()
IllegalStateException
- if this state is not a valid text state.char[] getTextCharacters()
IllegalStateException
- if this state is not a valid text state.int getTextCharacters(int sourceStart, char[] target, int targetStart, int length) throws XMLStreamException
int length = 1024;
char[] myBuffer = new char[ length ];
for ( int sourceStart = 0 ; ; sourceStart += length )
{
int nCopied = stream.getTextCharacters( sourceStart, myBuffer, 0, length );
if (nCopied < length)
break;
}
XMLStreamException may be thrown if there are any XML errors in the underlying source. The "targetStart" argument must be greater than or equal to 0 and less than the length of "target", Length must be greater than 0 and "targetStart + length" must be less than or equal to length of "target".sourceStart
- the index of the first character in the source array to copytarget
- the destination arraytargetStart
- the start offset in the target arraylength
- the number of characters to copyXMLStreamException
- if the underlying XML source is not well-formedIndexOutOfBoundsException
- if targetStart < 0 or > than the length of targetIndexOutOfBoundsException
- if length < 0 or targetStart + length > length of targetUnsupportedOperationException
- if this method is not supportedNullPointerException
- is if target is nullint getTextStart()
IllegalStateException
- if this state is not a valid text state.int getTextLength()
IllegalStateException
- if this state is not a valid text state.String getEncoding()
boolean hasText()
Location getLocation()
QName getName()
IllegalStateException
- if this is not a START_ELEMENT or END_ELEMENTString getLocalName()
IllegalStateException
- if this not a START_ELEMENT, END_ELEMENT or ENTITY_REFERENCEboolean hasName()
String getNamespaceURI()
String getPrefix()
String getVersion()
boolean isStandalone()
boolean standaloneSet()
String getCharacterEncodingScheme()
String getPITarget()
String getPIData()
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Documentation extracted from Debian's OpenJDK Development Kit package.
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