StreamReaderDelegate (Java EE 5 SDK)

javax.xml.stream.util Class StreamReaderDelegate

java.lang.Object
  javax.xml.stream.util.StreamReaderDelegate

所有已实现的接口:

XMLStreamConstants, XMLStreamReader

public class StreamReaderDelegate

extends Object

implements XMLStreamReader

This is the base class for deriving an XMLStreamReader filter This class is designed to sit between an XMLStreamReader and an application's XMLStreamReader. By default each method does nothing but call the corresponding method on the parent interface.

版本:

1.0

作者:

Copyright (c) 2003 by BEA Systems. All Rights Reserved.

另请参见:

XMLStreamReader, EventReaderDelegate

StreamReaderDelegate

public StreamReaderDelegate()

Construct an empty filter with no parent.

StreamReaderDelegate

public StreamReaderDelegate(XMLStreamReader reader)

Construct an filter with the specified parent.

参数:

reader - the parent

setParent

public void setParent(XMLStreamReader reader)

Set the parent of this instance.

参数:

reader - the new parent

getParent

public XMLStreamReader getParent()

Get the parent of this instance.

返回:

the parent or null if none is set

next

public int next()
         throws XMLStreamException

Description copied from interface: XMLStreamReader

Get next parsing event - a processor may return all contiguous character data in a single chunk, or it may split it into several chunks. If the property javax.xml.stream.isCoalescing is set to true element content must be coalesced and only one CHARACTERS event must be returned for contiguous element content or CDATA Sections. By default entity references must be expanded and reported transparently to the application. An exception will be thrown if an entity reference cannot be expanded. If element content is empty (i.e. content is "") then no CHARACTERS event will be reported.

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

注意: 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>. This method will throw an IllegalStateException if it is called after hasNext() returns false.

规范说明:

next in interface XMLStreamReader

返回:

the integer code corresponding to the current parse event

抛出异常:

XMLStreamException - if there is an error processing the underlying XML source

另请参见:

XMLEvent

nextTag

public int nextTag()
            throws XMLStreamException

Description copied from interface: XMLStreamReader

Skips any white space (isWhiteSpace() returns true), COMMENT, or PROCESSING_INSTRUCTION, until a START_ELEMENT or END_ELEMENT is reached. If other than white space characters, COMMENT, PROCESSING_INSTRUCTION, START_ELEMENT, END_ELEMENT are encountered, an exception is thrown. This method should be used when processing element-only content seperated by white space.
Precondition: none
Postcondition: the current event is START_ELEMENT or END_ELEMENT and cursor may have moved over any whitespace event.
Essentially it does the following (implementations are free to optimized but must do equivalent processing):

 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;
 

规范说明:

nextTag in interface XMLStreamReader

返回:

the event type of the element read (START_ELEMENT or END_ELEMENT)

抛出异常:

XMLStreamException - if the current event is not white space, PROCESSING_INSTRUCTION, START_ELEMENT or END_ELEMENT

getElementText

public String getElementText()
                      throws XMLStreamException

Description copied from interface: XMLStreamReader

Reads the content of a text-only element, an exception is thrown if this is not a text-only element. Regardless of value of javax.xml.stream.isCoalescing this method always returns coalesced content.
Precondition: the current event is START_ELEMENT.
Postcondition: the current event is the corresponding END_ELEMENT.
The method does the following (implementations are free to optimized but must do equivalent processing):

 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();
 

规范说明:

getElementText in interface XMLStreamReader

抛出异常:

XMLStreamException - if the current event is not a START_ELEMENT or if a non text element is encountered

require

public void require(int type,
                    String namespaceURI,
                    String localName)
             throws XMLStreamException

Description copied from interface: XMLStreamReader

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. If the namespaceURI is null it is not checked for equality, if the localName is null it is not checked for equality.

规范说明:

require in interface XMLStreamReader

参数:

type - the event type

namespaceURI - the uri of the event, may be null

localName - the localName of the event, may be null

抛出异常:

XMLStreamException - if the required values are not matched.

hasNext

public boolean hasNext()
                throws XMLStreamException

Description copied from interface: XMLStreamReader

Returns true if there are more parsing events and false if there are no more events. This method will return false if the current state of the XMLStreamReader is END_DOCUMENT

规范说明:

hasNext in interface XMLStreamReader

返回:

true if there are more events, false otherwise

抛出异常:

XMLStreamException - if there is a fatal error detecting the next state

close

public void close()
           throws XMLStreamException

Description copied from interface: XMLStreamReader

Frees any resources associated with this Reader. This method does not close the underlying input source.

规范说明:

close in interface XMLStreamReader

抛出异常:

XMLStreamException - if there are errors freeing associated resources

getNamespaceURI

public String getNamespaceURI(String prefix)

Description copied from interface: XMLStreamReader

Return the uri for the given prefix. The uri returned depends on the current state of the processor.

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/

规范说明:

getNamespaceURI in interface XMLStreamReader

参数:

prefix - The prefix to lookup, may not be null

返回:

the uri bound to the given prefix or null if it is not bound

getNamespaceContext

public NamespaceContext getNamespaceContext()

Description copied from interface: XMLStreamReader

Returns a read only namespace context for the current position. The context is transient and only valid until a call to next() changes the state of the reader.

规范说明:

getNamespaceContext in interface XMLStreamReader

返回:

return a namespace context

isStartElement

public boolean isStartElement()

Description copied from interface: XMLStreamReader

Returns true if the cursor points to a start tag (otherwise false)

规范说明:

isStartElement in interface XMLStreamReader

返回:

true if the cursor points to a start tag, false otherwise

isEndElement

public boolean isEndElement()

Description copied from interface: XMLStreamReader

Returns true if the cursor points to an end tag (otherwise false)

规范说明:

isEndElement in interface XMLStreamReader

返回:

true if the cursor points to an end tag, false otherwise

isCharacters

public boolean isCharacters()

Description copied from interface: XMLStreamReader

Returns true if the cursor points to a character data event

规范说明:

isCharacters in interface XMLStreamReader

返回:

true if the cursor points to character data, false otherwise

isWhiteSpace

public boolean isWhiteSpace()

Description copied from interface: XMLStreamReader

Returns true if the cursor points to a character data event that consists of all whitespace

规范说明:

isWhiteSpace in interface XMLStreamReader

返回:

true if the cursor points to all whitespace, false otherwise

getAttributeValue

public String getAttributeValue(String namespaceUri,
                                String localName)

Description copied from interface: XMLStreamReader

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

规范说明:

getAttributeValue in interface XMLStreamReader

参数:

namespaceUri - the namespace of the attribute

localName - the local name of the attribute, cannot be null

返回:

returns the value of the attribute , returns null if not found

getAttributeCount

public int getAttributeCount()

Description copied from interface: XMLStreamReader

Returns the count of attributes on this START_ELEMENT, this method is only valid on a START_ELEMENT or ATTRIBUTE. This count excludes namespace definitions. Attribute indices are zero-based.

规范说明:

getAttributeCount in interface XMLStreamReader

返回:

returns the number of attributes

getAttributeName

public QName getAttributeName(int index)

Description copied from interface: XMLStreamReader

Returns the qname of the attribute at the provided index

规范说明:

getAttributeName in interface XMLStreamReader

参数:

index - the position of the attribute

返回:

the QName of the attribute

getAttributePrefix

public String getAttributePrefix(int index)

Description copied from interface: XMLStreamReader

Returns the prefix of this attribute at the provided index

规范说明:

getAttributePrefix in interface XMLStreamReader

参数:

index - the position of the attribute

返回:

the prefix of the attribute

getAttributeNamespace

public String getAttributeNamespace(int index)

Description copied from interface: XMLStreamReader

Returns the namespace of the attribute at the provided index

规范说明:

getAttributeNamespace in interface XMLStreamReader

参数:

index - the position of the attribute

返回:

the namespace URI (can be null)

getAttributeLocalName

public String getAttributeLocalName(int index)

Description copied from interface: XMLStreamReader

Returns the localName of the attribute at the provided index

规范说明:

getAttributeLocalName in interface XMLStreamReader

参数:

index - the position of the attribute

返回:

the localName of the attribute

getAttributeType

public String getAttributeType(int index)

Description copied from interface: XMLStreamReader

Returns the XML type of the attribute at the provided index

规范说明:

getAttributeType in interface XMLStreamReader

参数:

index - the position of the attribute

返回:

the XML type of the attribute

getAttributeValue

public String getAttributeValue(int index)

Description copied from interface: XMLStreamReader

Returns the value of the attribute at the index

规范说明:

getAttributeValue in interface XMLStreamReader

参数:

index - the position of the attribute

返回:

the attribute value

isAttributeSpecified

public boolean isAttributeSpecified(int index)

Description copied from interface: XMLStreamReader

Returns a boolean which indicates if this attribute was created by default

规范说明:

isAttributeSpecified in interface XMLStreamReader

参数:

index - the position of the attribute

返回:

true if this is a default attribute

getNamespaceCount

public int getNamespaceCount()

Description copied from interface: XMLStreamReader

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. On an END_ELEMENT the count is of the namespaces that are about to go out of scope. This is the equivalent of the information reported by SAX callback for an end element event.

规范说明:

getNamespaceCount in interface XMLStreamReader

返回:

returns the number of namespace declarations on this specific element

getNamespacePrefix

public String getNamespacePrefix(int index)

Description copied from interface: XMLStreamReader

Returns the prefix for the namespace declared at the index. Returns null if this is the default namespace declaration

规范说明:

getNamespacePrefix in interface XMLStreamReader

参数:

index - the position of the namespace declaration

返回:

returns the namespace prefix

getNamespaceURI

public String getNamespaceURI(int index)

Description copied from interface: XMLStreamReader

Returns the uri for the namespace declared at the index.

规范说明:

getNamespaceURI in interface XMLStreamReader

参数:

index - the position of the namespace declaration

返回:

returns the namespace uri

getEventType

public int getEventType()

Description copied from interface: XMLStreamReader

Returns an integer code that indicates the type of the event the cursor is pointing to.

规范说明:

getEventType in interface XMLStreamReader

getText

public String getText()

Description copied from interface: XMLStreamReader

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. If an ENTITY_REFERENCE has been resolved, any character data will be reported as CHARACTERS events.

规范说明:

getText in interface XMLStreamReader

返回:

the current text or null

getTextCharacters

public int getTextCharacters(int sourceStart,
                             char[] target,
                             int targetStart,
                             int length)
                      throws XMLStreamException

Description copied from interface: XMLStreamReader

Gets the the text associated with a CHARACTERS, SPACE or CDATA event. Text starting a "sourceStart" is copied into "target" starting at "targetStart". Up to "length" characters are copied. The number of characters actually copied is returned. The "sourceStart" argument must be greater or equal to 0 and less than or equal to the number of characters associated with the event. Usually, one requests text starting at a "sourceStart" of 0. If the number of characters actually copied is less than the "length", then there is no more text. Otherwise, subsequent calls need to be made until all text has been retrieved. For example: 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".

规范说明:

getTextCharacters in interface XMLStreamReader

参数:

sourceStart - the index of the first character in the source array to copy

target - the destination array

targetStart - the start offset in the target array

length - the number of characters to copy

返回:

the number of characters actually copied

抛出异常:

XMLStreamException - if the underlying XML source is not well-formed

getTextCharacters

public char[] getTextCharacters()

Description copied from interface: XMLStreamReader

Returns an array which contains the characters from this event. This array should be treated as read-only and transient. I.e. the array will contain the text characters until the XMLStreamReader moves on to the next event. Attempts to hold onto the character array beyond that time or modify the contents of the array are breaches of the contract for this interface.

规范说明:

getTextCharacters in interface XMLStreamReader

返回:

the current text or an empty array

getTextStart

public int getTextStart()

Description copied from interface: XMLStreamReader

Returns the offset into the text character array where the first character (of this text event) is stored.

规范说明:

getTextStart in interface XMLStreamReader

getTextLength

public int getTextLength()

Description copied from interface: XMLStreamReader

Returns the length of the sequence of characters for this Text event within the text character array.

规范说明:

getTextLength in interface XMLStreamReader

getEncoding

public String getEncoding()

Description copied from interface: XMLStreamReader

Return input encoding if known or null if unknown.

规范说明:

getEncoding in interface XMLStreamReader

返回:

the encoding of this instance or null

hasText

public boolean hasText()

Description copied from interface: XMLStreamReader

Return true if the current event has text, false otherwise The following events have text: CHARACTERS,DTD ,ENTITY_REFERENCE, COMMENT, SPACE

规范说明:

hasText in interface XMLStreamReader

getLocation

public Location getLocation()

Description copied from interface: XMLStreamReader

Return the current location of the processor. If the Location is unknown the processor should return an implementation of Location that returns -1 for the location and null for the publicId and systemId. The location information is only valid until next() is called.

规范说明:

getLocation in interface XMLStreamReader

getName

public QName getName()

Description copied from interface: XMLStreamReader

Returns a QName for the current START_ELEMENT or END_ELEMENT event

规范说明:

getName in interface XMLStreamReader

返回:

the QName for the current START_ELEMENT or END_ELEMENT event

getLocalName

public String getLocalName()

Description copied from interface: XMLStreamReader

Returns the (local) name of the current event. For START_ELEMENT or END_ELEMENT returns the (local) name of the current element. For ENTITY_REFERENCE it returns entity name. The current event must be START_ELEMENT or END_ELEMENT, or ENTITY_REFERENCE

规范说明:

getLocalName in interface XMLStreamReader

返回:

the localName

hasName

public boolean hasName()

Description copied from interface: XMLStreamReader

returns true if the current event has a name (is a START_ELEMENT or END_ELEMENT) returns false otherwise

规范说明:

hasName in interface XMLStreamReader

getNamespaceURI

public String getNamespaceURI()

Description copied from interface: XMLStreamReader

If the current event is a START_ELEMENT or END_ELEMENT this method returns the URI of the prefix or the default namespace. Returns null if the event does not have a prefix.

规范说明:

getNamespaceURI in interface XMLStreamReader

返回:

the URI bound to this elements prefix, the default namespace, or null

getPrefix

public String getPrefix()

Description copied from interface: XMLStreamReader

Returns the prefix of the current event or null if the event does not have a prefix

规范说明:

getPrefix in interface XMLStreamReader

返回:

the prefix or null

getVersion

public String getVersion()

Description copied from interface: XMLStreamReader

Get the xml version declared on the xml declaration Returns null if none was declared

规范说明:

getVersion in interface XMLStreamReader

返回:

the XML version or null

isStandalone

public boolean isStandalone()

Description copied from interface: XMLStreamReader

Get the standalone declaration from the xml declaration

规范说明:

isStandalone in interface XMLStreamReader

返回:

true if this is standalone, or false otherwise

standaloneSet

public boolean standaloneSet()

Description copied from interface: XMLStreamReader

Checks if standalone was set in the document

规范说明:

standaloneSet in interface XMLStreamReader

返回:

true if standalone was set in the document, or false otherwise

getCharacterEncodingScheme

public String getCharacterEncodingScheme()

Description copied from interface: XMLStreamReader

Returns the character encoding declared on the xml declaration Returns null if none was declared

规范说明:

getCharacterEncodingScheme in interface XMLStreamReader

返回:

the encoding declared in the document or null

getPITarget

public String getPITarget()

Description copied from interface: XMLStreamReader

Get the target of a processing instruction

规范说明:

getPITarget in interface XMLStreamReader

返回:

the target or null

getPIData

public String getPIData()

Description copied from interface: XMLStreamReader

Get the data section of a processing instruction

规范说明:

getPIData in interface XMLStreamReader

返回:

the data or null

getProperty

public Object getProperty(String name)

Description copied from interface: XMLStreamReader

Get the value of a feature/property from the underlying implementation

规范说明:

getProperty in interface XMLStreamReader

参数:

name - The name of the property, may not be null

返回:

The value of the property

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