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Java example source code file (XMLStreamReader.java)
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The XMLStreamReader.java Java example source code
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* Copyright (c) 2009 by Oracle Corporation. All Rights Reserved.
*/
package javax.xml.stream;
import java.io.Reader;
import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
/**
* The XMLStreamReader interface allows forward, read-only access to XML.
* It is designed to be the lowest level and most efficient way to
* read XML data.
*
* <p> 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();
*
* <p> The next() method causes the reader to read the next parse event.
* The next() method returns an integer which identifies the type of event just read.
* <p> The event type can be determined using getEventType().
* <p> 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.
*
* <p>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
* <code>List l = (List) getProperty("javax.xml.stream.notations");
* The following call will return a list of entity declarations:
* <code>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.
*
* <p>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.
*
* <table border="2" rules="all" cellpadding="4">
* <thead>
* <tr>
* <th align="center" colspan="2">
* Valid methods for each state
* </th>
* </tr>
* </thead>
* <tbody>
* <tr>
* <th>Event Type
* <th>Valid Methods
* </tr>
* <tr>
* <td> All States |
* <td> getProperty(), hasNext(), require(), close(),
* getNamespaceURI(), isStartElement(),
* isEndElement(), isCharacters(), isWhiteSpace(),
* getNamespaceContext(), getEventType(),getLocation(),
* hasText(), hasName()
* </td>
* </tr>
* <tr>
* <td> START_ELEMENT
* <td> next(), getName(), getLocalName(), hasName(), getPrefix(),
* getAttributeXXX(), isAttributeSpecified(),
* getNamespaceXXX(),
* getElementText(), nextTag()
* </td>
* </tr>
* <td> ATTRIBUTE
* <td> next(), nextTag()
* getAttributeXXX(), isAttributeSpecified(),
* </td>
* </tr>
* </tr>
* <td> NAMESPACE
* <td> next(), nextTag()
* getNamespaceXXX()
* </td>
* </tr>
* <tr>
* <td> END_ELEMENT
* <td> next(), getName(), getLocalName(), hasName(), getPrefix(),
* getNamespaceXXX(), nextTag()
* </td>
* </tr>
* <tr>
* <td> CHARACTERS
* <td> next(), getTextXXX(), nextTag()
* </tr>
* <tr>
* <td> CDATA
* <td> next(), getTextXXX(), nextTag()
* </tr>
* <tr>
* <td> COMMENT
* <td> next(), getTextXXX(), nextTag()
* </tr>
* <tr>
* <td> SPACE
* <td> next(), getTextXXX(), nextTag()
* </tr>
* <tr>
* <td> START_DOCUMENT
* <td> next(), getEncoding(), getVersion(), isStandalone(), standaloneSet(),
* getCharacterEncodingScheme(), nextTag()</td>
* </tr>
* <tr>
* <td> END_DOCUMENT
* <td> close()
* </tr>
* <tr>
* <td> PROCESSING_INSTRUCTION
* <td> next(), getPITarget(), getPIData(), nextTag()
* </tr>
* <tr>
* <td> ENTITY_REFERENCE
* <td> next(), getLocalName(), getText(), nextTag()
* </tr>
* <tr>
* <td> DTD
* <td> next(), getText(), nextTag()
* </tr>
* </tbody>
* </table>
*
* @version 1.0
* @author Copyright (c) 2009 by Oracle Corporation. All Rights Reserved.
* @see javax.xml.stream.events.XMLEvent
* @see XMLInputFactory
* @see XMLStreamWriter
* @since 1.6
*/
public interface XMLStreamReader extends XMLStreamConstants {
/**
* Get the value of a feature/property from the underlying implementation
* @param name The name of the property, may not be null
* @return The value of the property
* @throws IllegalArgumentException if name is null
*/
public Object getProperty(java.lang.String name) throws java.lang.IllegalArgumentException;
/**
* 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.
*
* <p>Given the following XML:
* <foo><!--description-->content text<![CDATA[<greeting>Hello</greeting>]]>other content</foo><br>
* The behavior of calling next() when being on foo will be:<br>
* 1- the comment (COMMENT)<br>
* 2- then the characters section (CHARACTERS)<br>
* 3- then the CDATA section (another CHARACTERS)<br>
* 4- then the next characters section (another CHARACTERS)<br>
* 5- then the END_ELEMENT<br>
*
* <p>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>.
*
* This method will throw an IllegalStateException if it is called after hasNext() returns false.
* @see javax.xml.stream.events.XMLEvent
* @return the integer code corresponding to the current parse event
* @throws NoSuchElementException if this is called when hasNext() returns false
* @throws XMLStreamException if there is an error processing the underlying XML source
*/
public int next() throws XMLStreamException;
/**
* 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.
* @param type the event type
* @param namespaceURI the uri of the event, may be null
* @param localName the localName of the event, may be null
* @throws XMLStreamException if the required values are not matched.
*/
public void require(int type, String namespaceURI, String localName) throws XMLStreamException;
/**
* 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.
* <br /> Precondition: the current event is START_ELEMENT.
* <br /> Postcondition: the current event is the corresponding END_ELEMENT.
*
* <br />The method does the following (implementations are free to optimized
* but must do equivalent processing):
* <pre>
* 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();
* </pre>
*
* @throws XMLStreamException if the current event is not a START_ELEMENT
* or if a non text element is encountered
*/
public String getElementText() throws XMLStreamException;
/**
* 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.
*
* <br /> Precondition: none
* <br /> Postcondition: the current event is START_ELEMENT or END_ELEMENT
* and cursor may have moved over any whitespace event.
*
* <br />Essentially it does the following (implementations are free to optimized
* but must do equivalent processing):
* <pre>
* 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;
* </pre>
*
* @return the event type of the element read (START_ELEMENT or END_ELEMENT)
* @throws XMLStreamException if the current event is not white space, PROCESSING_INSTRUCTION,
* START_ELEMENT or END_ELEMENT
* @throws NoSuchElementException if this is called when hasNext() returns false
*/
public int nextTag() throws XMLStreamException;
/**
* 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
* @return true if there are more events, false otherwise
* @throws XMLStreamException if there is a fatal error detecting the next state
*/
public boolean hasNext() throws XMLStreamException;
/**
* Frees any resources associated with this Reader. This method does not close the
* underlying input source.
* @throws XMLStreamException if there are errors freeing associated resources
*/
public void close() throws XMLStreamException;
/**
* Return the uri for the given prefix.
* The uri returned depends on the current state of the processor.
*
* <p>NOTE:The 'xml' prefix is bound as defined in
* <a href="http://www.w3.org/TR/REC-xml-names/#ns-using">Namespaces in XML
* specification to "http://www.w3.org/XML/1998/namespace".
*
* <p>NOTE: The 'xmlns' prefix must be resolved to following namespace
* <a href="http://www.w3.org/2000/xmlns/">http://www.w3.org/2000/xmlns/
* @param prefix The prefix to lookup, may not be null
* @return the uri bound to the given prefix or null if it is not bound
* @throws IllegalArgumentException if the prefix is null
*/
public String getNamespaceURI(String prefix);
/**
* Returns true if the cursor points to a start tag (otherwise false)
* @return true if the cursor points to a start tag, false otherwise
*/
public boolean isStartElement();
/**
* Returns true if the cursor points to an end tag (otherwise false)
* @return true if the cursor points to an end tag, false otherwise
*/
public boolean isEndElement();
/**
* Returns true if the cursor points to a character data event
* @return true if the cursor points to character data, false otherwise
*/
public boolean isCharacters();
/**
* Returns true if the cursor points to a character data event
* that consists of all whitespace
* @return true if the cursor points to all whitespace, false otherwise
*/
public boolean isWhiteSpace();
/**
* 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
* @param namespaceURI the namespace of the attribute
* @param localName the local name of the attribute, cannot be null
* @return returns the value of the attribute , returns null if not found
* @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
*/
public String getAttributeValue(String namespaceURI,
String localName);
/**
* 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.
* @return returns the number of attributes
* @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
*/
public int getAttributeCount();
/** Returns the qname of the attribute at the provided index
*
* @param index the position of the attribute
* @return the QName of the attribute
* @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
*/
public QName getAttributeName(int index);
/**
* Returns the namespace of the attribute at the provided
* index
* @param index the position of the attribute
* @return the namespace URI (can be null)
* @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
*/
public String getAttributeNamespace(int index);
/**
* Returns the localName of the attribute at the provided
* index
* @param index the position of the attribute
* @return the localName of the attribute
* @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
*/
public String getAttributeLocalName(int index);
/**
* Returns the prefix of this attribute at the
* provided index
* @param index the position of the attribute
* @return the prefix of the attribute
* @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
*/
public String getAttributePrefix(int index);
/**
* Returns the XML type of the attribute at the provided
* index
* @param index the position of the attribute
* @return the XML type of the attribute
* @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
*/
public String getAttributeType(int index);
/**
* Returns the value of the attribute at the
* index
* @param index the position of the attribute
* @return the attribute value
* @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
*/
public String getAttributeValue(int index);
/**
* Returns a boolean which indicates if this
* attribute was created by default
* @param index the position of the attribute
* @return true if this is a default attribute
* @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
*/
public boolean isAttributeSpecified(int index);
/**
* 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.
* @return returns the number of namespace declarations on this specific element
* @throws IllegalStateException if this is not a START_ELEMENT, END_ELEMENT or NAMESPACE
*/
public int getNamespaceCount();
/**
* Returns the prefix for the namespace declared at the
* index. Returns null if this is the default namespace
* declaration
*
* @param index the position of the namespace declaration
* @return returns the namespace prefix
* @throws IllegalStateException if this is not a START_ELEMENT, END_ELEMENT or NAMESPACE
*/
public String getNamespacePrefix(int index);
/**
* Returns the uri for the namespace declared at the
* index.
*
* @param index the position of the namespace declaration
* @return returns the namespace uri
* @throws IllegalStateException if this is not a START_ELEMENT, END_ELEMENT or NAMESPACE
*/
public String getNamespaceURI(int index);
/**
* 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.
* @return return a namespace context
*/
public NamespaceContext getNamespaceContext();
/**
* Returns a reader that points to the current start element
* and all of its contents. Throws an XMLStreamException if the
* cursor does not point to a START_ELEMENT.<p>
* The sub stream is read from it MUST be read before the parent stream is
* moved on, if not any call on the sub stream will cause an XMLStreamException to be
* thrown. The parent stream will always return the same result from next()
* whatever is done to the sub stream.
* @return an XMLStreamReader which points to the next element
*/
// public XMLStreamReader subReader() throws XMLStreamException;
/**
* Allows the implementation to reset and reuse any underlying tables
*/
// public void recycle() throws XMLStreamException;
/**
* Returns an integer code that indicates the type
* of the event the cursor is pointing to.
*/
public int getEventType();
/**
* 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.
* @return the current text or null
* @throws java.lang.IllegalStateException if this state is not
* a valid text state.
*/
public String getText();
/**
* 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.
* @return the current text or an empty array
* @throws java.lang.IllegalStateException if this state is not
* a valid text state.
*/
public char[] getTextCharacters();
/**
* 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:
*
*<code>
* 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;
* }
* </code>
* 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".
*
* @param sourceStart the index of the first character in the source array to copy
* @param target the destination array
* @param targetStart the start offset in the target array
* @param length the number of characters to copy
* @return the number of characters actually copied
* @throws XMLStreamException if the underlying XML source is not well-formed
* @throws IndexOutOfBoundsException if targetStart < 0 or > than the length of target
* @throws IndexOutOfBoundsException if length < 0 or targetStart + length > length of target
* @throws UnsupportedOperationException if this method is not supported
* @throws NullPointerException is if target is null
*/
public int getTextCharacters(int sourceStart, char[] target, int targetStart, int length)
throws XMLStreamException;
/**
* Gets the text associated with a CHARACTERS, SPACE or CDATA event. Allows the underlying
* implementation to return the text as a stream of characters. The reference to the
* Reader returned by this method is only valid until next() is called.
*
* All characters must have been checked for well-formedness.
*
* <p> This method is optional and will throw UnsupportedOperationException if it is not supported.
* @throws UnsupportedOperationException if this method is not supported
* @throws IllegalStateException if this is not a valid text state
*/
//public Reader getTextStream();
/**
* Returns the offset into the text character array where the first
* character (of this text event) is stored.
* @throws java.lang.IllegalStateException if this state is not
* a valid text state.
*/
public int getTextStart();
/**
* Returns the length of the sequence of characters for this
* Text event within the text character array.
* @throws java.lang.IllegalStateException if this state is not
* a valid text state.
*/
public int getTextLength();
/**
* Return input encoding if known or null if unknown.
* @return the encoding of this instance or null
*/
public String getEncoding();
/**
* Return true if the current event has text, false otherwise
* The following events have text:
* CHARACTERS,DTD ,ENTITY_REFERENCE, COMMENT, SPACE
*/
public boolean hasText();
/**
* 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.
*/
public Location getLocation();
/**
* Returns a QName for the current START_ELEMENT or END_ELEMENT event
* @return the QName for the current START_ELEMENT or END_ELEMENT event
* @throws IllegalStateException if this is not a START_ELEMENT or
* END_ELEMENT
*/
public QName getName();
/**
* 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
* @return the localName
* @throws IllegalStateException if this not a START_ELEMENT,
* END_ELEMENT or ENTITY_REFERENCE
*/
public String getLocalName();
/**
* returns true if the current event has a name (is a START_ELEMENT or END_ELEMENT)
* returns false otherwise
*/
public boolean hasName();
/**
* 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.
* @return the URI bound to this elements prefix, the default namespace, or null
*/
public String getNamespaceURI();
/**
* Returns the prefix of the current event or null if the event does not have a prefix
* @return the prefix or null
*/
public String getPrefix();
/**
* Get the xml version declared on the xml declaration
* Returns null if none was declared
* @return the XML version or null
*/
public String getVersion();
/**
* Get the standalone declaration from the xml declaration
* @return true if this is standalone, or false otherwise
*/
public boolean isStandalone();
/**
* Checks if standalone was set in the document
* @return true if standalone was set in the document, or false otherwise
*/
public boolean standaloneSet();
/**
* Returns the character encoding declared on the xml declaration
* Returns null if none was declared
* @return the encoding declared in the document or null
*/
public String getCharacterEncodingScheme();
/**
* Get the target of a processing instruction
* @return the target or null
*/
public String getPITarget();
/**
* Get the data section of a processing instruction
* @return the data or null
*/
public String getPIData();
}
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