QName represents a qualified name
* as defined in the XML specifications: XML Schema Part2:
* Datatypes specification, Namespaces
* in XML, Namespaces
* in XML Errata.
The value of a QName contains a Namespace
* URI, local part and
* prefix.
The prefix is included in QName to retain lexical
* information when present in an {@link
* javax.xml.transform.Source XML input source}. The prefix is
* NOT used in {@link #equals(Object)
* QName.equals(Object)} or to compute the {@link #hashCode()
* QName.hashCode()}. Equality and the hash code are defined using
* only the Namespace URI and local part.
If not specified, the Namespace URI is set to {@link * javax.xml.XMLConstants#NULL_NS_URI XMLConstants.NULL_NS_URI}. * If not specified, the prefix is set to {@link * javax.xml.XMLConstants#DEFAULT_NS_PREFIX * XMLConstants.DEFAULT_NS_PREFIX}.
* *QName is immutable.
Stream Unique Identifier.
* *Due to a historical defect, QName was released with multiple * serialVersionUID values even though its serialization was the * same.
* *To workaround this issue, serialVersionUID is set with either * a default value or a compatibility value. To use the * compatiblity value, set the system property:
* *com.sun.xml.namespace.QName.useCompatibleSerialVersionUID=1.0
*
* This workaround was inspired by classes in the javax.management * package, e.g. ObjectName, etc. * See CR6267224 for original defect report.
*/ private static final long serialVersionUID; /** *Default serialVersionUID value.
Compatibility serialVersionUID value.
Flag to use default or campatible serialVersionUID.
*/ private static boolean useDefaultSerialVersionUID = true; static { try { // use a privileged block as reading a system property String valueUseCompatibleSerialVersionUID = (String) AccessController.doPrivileged( new PrivilegedAction() { public Object run() { return System.getProperty("com.sun.xml.namespace.QName.useCompatibleSerialVersionUID"); } } ); useDefaultSerialVersionUID = (valueUseCompatibleSerialVersionUID != null && valueUseCompatibleSerialVersionUID.equals("1.0")) ? false : true; } catch (Exception exception) { // use default if any Exceptions useDefaultSerialVersionUID = true; } // set serialVersionUID to desired value if (useDefaultSerialVersionUID) { serialVersionUID = defaultSerialVersionUID; } else { serialVersionUID = compatibleSerialVersionUID; } } /** *Namespace URI of this QName.
local part of this QName.
prefix of this QName.
QName constructor specifying the Namespace URI
* and local part.
If the Namespace URI is null, it is set to
* {@link javax.xml.XMLConstants#NULL_NS_URI
* XMLConstants.NULL_NS_URI}. This value represents no
* explicitly defined Namespace as defined by the Namespaces
* in XML specification. This action preserves compatible
* behavior with QName 1.0. Explicitly providing the {@link
* javax.xml.XMLConstants#NULL_NS_URI
* XMLConstants.NULL_NS_URI} value is the preferred coding
* style.
If the local part is null an
* IllegalArgumentException is thrown.
* A local part of "" is allowed to preserve
* compatible behavior with QName 1.0.
When using this constructor, the prefix is set to {@link * javax.xml.XMLConstants#DEFAULT_NS_PREFIX * XMLConstants.DEFAULT_NS_PREFIX}.
* *The Namespace URI is not validated as a * URI reference. * The local part is not validated as a * NCName * as specified in Namespaces * in XML.
* * @param namespaceURI Namespace URI of theQName
* @param localPart local part of the QName
*
* @throws IllegalArgumentException When localPart is
* null
*
* @see #QName(String namespaceURI, String localPart, String
* prefix) QName(String namespaceURI, String localPart, String
* prefix)
*/
public QName(final String namespaceURI, final String localPart) {
this(namespaceURI, localPart, XMLConstants.DEFAULT_NS_PREFIX);
}
/**
* QName constructor specifying the Namespace URI,
* local part and prefix.
If the Namespace URI is null, it is set to
* {@link javax.xml.XMLConstants#NULL_NS_URI
* XMLConstants.NULL_NS_URI}. This value represents no
* explicitly defined Namespace as defined by the Namespaces
* in XML specification. This action preserves compatible
* behavior with QName 1.0. Explicitly providing the {@link
* javax.xml.XMLConstants#NULL_NS_URI
* XMLConstants.NULL_NS_URI} value is the preferred coding
* style.
If the local part is null an
* IllegalArgumentException is thrown.
* A local part of "" is allowed to preserve
* compatible behavior with QName 1.0.
If the prefix is null, an
* IllegalArgumentException is thrown. Use {@link
* javax.xml.XMLConstants#DEFAULT_NS_PREFIX
* XMLConstants.DEFAULT_NS_PREFIX} to explicitly indicate that no
* prefix is present or the prefix is not relevant.
The Namespace URI is not validated as a * URI reference. * The local part and prefix are not validated as a * NCName * as specified in Namespaces * in XML.
* * @param namespaceURI Namespace URI of theQName
* @param localPart local part of the QName
* @param prefix prefix of the QName
*
* @throws IllegalArgumentException When localPart
* or prefix is null
*/
public QName(String namespaceURI, String localPart, String prefix) {
// map null Namespace URI to default
// to preserve compatibility with QName 1.0
if (namespaceURI == null) {
this.namespaceURI = XMLConstants.NULL_NS_URI;
} else {
this.namespaceURI = namespaceURI;
}
// local part is required.
// "" is allowed to preserve compatibility with QName 1.0
if (localPart == null) {
throw new IllegalArgumentException(
"local part cannot be \"null\" when creating a QName");
}
this.localPart = localPart;
// prefix is required
if (prefix == null) {
throw new IllegalArgumentException(
"prefix cannot be \"null\" when creating a QName");
}
this.prefix = prefix;
}
/**
* QName constructor specifying the local part.
If the local part is null an
* IllegalArgumentException is thrown.
* A local part of "" is allowed to preserve
* compatible behavior with QName 1.0.
When using this constructor, the Namespace URI is set to * {@link javax.xml.XMLConstants#NULL_NS_URI * XMLConstants.NULL_NS_URI} and the prefix is set to {@link * javax.xml.XMLConstants#DEFAULT_NS_PREFIX * XMLConstants.DEFAULT_NS_PREFIX}.
* *In an XML context, all Element and Attribute names exist
* in the context of a Namespace. Making this explicit during the
* construction of a QName helps prevent hard to
* diagnosis XML validity errors. The constructors {@link
* #QName(String namespaceURI, String localPart) QName(String
* namespaceURI, String localPart)} and
* {@link #QName(String namespaceURI, String localPart, String prefix)}
* are preferred.
The local part is not validated as a * NCName * as specified in Namespaces * in XML.
* * @param localPart local part of theQName
*
* @throws IllegalArgumentException When localPart is
* null
*
* @see #QName(String namespaceURI, String localPart) QName(String
* namespaceURI, String localPart)
* @see #QName(String namespaceURI, String localPart, String
* prefix) QName(String namespaceURI, String localPart, String
* prefix)
*/
public QName(String localPart) {
this(
XMLConstants.NULL_NS_URI,
localPart,
XMLConstants.DEFAULT_NS_PREFIX);
}
/**
* Get the Namespace URI of this QName.
QName
*/
public String getNamespaceURI() {
return namespaceURI;
}
/**
* Get the local part of this QName.
QName
*/
public String getLocalPart() {
return localPart;
}
/**
* Get the prefix of this QName.
The prefix assigned to a QName might
* NOT be valid in a different
* context. For example, a QName may be assigned a
* prefix in the context of parsing a document but that prefix may
* be invalid in the context of a different document.
QName
*/
public String getPrefix() {
return prefix;
}
/**
* Test this QName for equality with another
* Object.
If the Object to be tested is not a
* QName or is null, then this method
* returns false.
Two QNames are considered equal if and only if
* both the Namespace URI and local part are equal. This method
* uses String.equals() to check equality of the
* Namespace URI and local part. The prefix is
* NOT used to determine equality.
This method satisfies the general contract of {@link * java.lang.Object#equals(Object) Object.equals(Object)}
* * @param objectToTest theObject to test for
* equality with this QName
* @return true if the given Object is
* equal to this QName else false
*/
public final boolean equals(Object objectToTest) {
if (objectToTest == this) {
return true;
}
if (objectToTest == null || !(objectToTest instanceof QName)) {
return false;
}
QName qName = (QName) objectToTest;
return localPart.equals(qName.localPart)
&& namespaceURI.equals(qName.namespaceURI);
}
/**
* Generate the hash code for this QName.
The hash code is calculated using both the Namespace URI and
* the local part of the QName. The prefix is
* NOT used to calculate the hash
* code.
This method satisfies the general contract of {@link * java.lang.Object#hashCode() Object.hashCode()}.
* * @return hash code for thisQName Object
*/
public final int hashCode() {
return namespaceURI.hashCode() ^ localPart.hashCode();
}
/**
* String representation of this
* QName.
The commonly accepted way of representing a QName
* as a String was
* defined
* by James Clark. Although this is not a standard
* specification, it is in common use, e.g. {@link
* javax.xml.transform.Transformer#setParameter(String name, Object value)}.
* This implementation represents a QName as:
* "{" + Namespace URI + "}" + local part. If the Namespace URI
* .equals(XMLConstants.NULL_NS_URI), only the
* local part is returned. An appropriate use of this method is
* for debugging or logging for human consumption.
Note the prefix value is NOT
* returned as part of the String representation.
This method satisfies the general contract of {@link * java.lang.Object#toString() Object.toString()}.
* * @returnString representation of this QName
*/
public String toString() {
if (namespaceURI.equals(XMLConstants.NULL_NS_URI)) {
return localPart;
} else {
return "{" + namespaceURI + "}" + localPart;
}
}
/**
* QName derived from parsing the formatted
* String.
If the String is null or does not conform to
* {@link #toString() QName.toString()} formatting, an
* IllegalArgumentException is thrown.
The String MUST be in the
* form returned by {@link #toString() QName.toString()}.
The commonly accepted way of representing a QName
* as a String was
* defined
* by James Clark. Although this is not a standard
* specification, it is in common use, e.g. {@link
* javax.xml.transform.Transformer#setParameter(String name, Object value)}.
* This implementation parses a String formatted
* as: "{" + Namespace URI + "}" + local part. If the Namespace
* URI .equals(XMLConstants.NULL_NS_URI), only the
* local part should be provided.
The prefix value CANNOT be
* represented in the String and will be set to
* {@link javax.xml.XMLConstants#DEFAULT_NS_PREFIX
* XMLConstants.DEFAULT_NS_PREFIX}.
This method does not do full validation of the resulting
* QName.
*
The Namespace URI is not validated as a * URI reference. * The local part is not validated as a * NCName * as specified in * Namespaces in XML.
* * @param qNameAsStringString representation
* of the QName
*
* @throws IllegalArgumentException When qNameAsString is
* null or malformed
*
* @return QName corresponding to the given String
* @see #toString() QName.toString()
*/
public static QName valueOf(String qNameAsString) {
// null is not valid
if (qNameAsString == null) {
throw new IllegalArgumentException(
"cannot create QName from \"null\" or \"\" String");
}
// "" local part is valid to preserve compatible behavior with QName 1.0
if (qNameAsString.length() == 0) {
return new QName(
XMLConstants.NULL_NS_URI,
qNameAsString,
XMLConstants.DEFAULT_NS_PREFIX);
}
// local part only?
if (qNameAsString.charAt(0) != '{') {
return new QName(
XMLConstants.NULL_NS_URI,
qNameAsString,
XMLConstants.DEFAULT_NS_PREFIX);
}
// Namespace URI improperly specified?
if (qNameAsString.startsWith("{" + XMLConstants.NULL_NS_URI + "}")) {
throw new IllegalArgumentException(
"Namespace URI .equals(XMLConstants.NULL_NS_URI), "
+ ".equals(\"" + XMLConstants.NULL_NS_URI + "\"), "
+ "only the local part, "
+ "\""
+ qNameAsString.substring(2 + XMLConstants.NULL_NS_URI.length())
+ "\", "
+ "should be provided.");
}
// Namespace URI and local part specified
int endOfNamespaceURI = qNameAsString.indexOf('}');
if (endOfNamespaceURI == -1) {
throw new IllegalArgumentException(
"cannot create QName from \""
+ qNameAsString
+ "\", missing closing \"}\"");
}
return new QName(
qNameAsString.substring(1, endOfNamespaceURI),
qNameAsString.substring(endOfNamespaceURI + 1),
XMLConstants.DEFAULT_NS_PREFIX);
}
}