javax.xml.namespace.QName Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// $Id: QName.java 754581 2009-03-15 01:32:39Z mrglavas $
package javax.xml.namespace;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import javax.xml.XMLConstants;
/**
* 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.
*
* @author Jeff Suttor
* @version $Revision: 754581 $, $Date: 2009-03-14 18:32:39 -0700 (Sat, 14 Mar 2009) $
* @see XML Schema Part2: Datatypes specification
* @see Namespaces in XML
* @see Namespaces in XML Errata
* @since 1.5
*/
public class QName implements Serializable {
/**
* Stream Unique Identifier.
*
* To enable the compatibility serialVersionUID
* set the System Property
* org.apache.xml.namespace.QName.useCompatibleSerialVersionUID
* to a value of "1.0".
*/
private static final long serialVersionUID;
/**
* The original default Stream Unique Identifier.
*/
private static final long defaultSerialVersionUID = -9120448754896609940L;
/**
* The compatibility Stream Unique Identifier that was introduced
* with Java 5 SE SDK.
*/
private static final long compatibilitySerialVersionUID = 4418622981026545151L;
static {
String compatPropValue = System.getProperty("org.apache.xml.namespace.QName.useCompatibleSerialVersionUID");
// If 1.0 use compatibility serialVersionUID
serialVersionUID = !"1.0".equals(compatPropValue) ? defaultSerialVersionUID : compatibilitySerialVersionUID;
}
/**
* Namespace URI of this QName.
*/
private final String namespaceURI;
/**
* local part of this QName.
*/
private final String localPart;
/**
* prefix of this QName.
*/
private String prefix;
/**
* String representation of this QName.
*/
private transient String qNameAsString;
/**
* 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 the QName
* @param localPart local part of the QName
*
* @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 the QName
* @param localPart local part of the QName
* @param prefix prefix of the QName
*/
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 the QName
* @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.
*
* @return Namespace URI of this QName
*/
public String getNamespaceURI() {
return namespaceURI;
}
/**
* Get the local part of this QName.
*
* @return local part of this 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.
*
* @return prefix of this 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 the Object 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) {
// Is this the same object?
if (objectToTest == this) {
return true;
}
// Is this a QName?
if (objectToTest instanceof QName) {
QName qName = (QName) objectToTest;
return localPart.equals(qName.localPart) && namespaceURI.equals(qName.namespaceURI);
}
return false;
}
/**
* 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 this QName 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()}.
*
* @return String representation of this QName
*/
public String toString() {
String _qNameAsString = qNameAsString;
if (_qNameAsString == null) {
final int nsLength = namespaceURI.length();
if (nsLength == 0) {
_qNameAsString = localPart;
}
else {
StringBuilder buffer = new StringBuilder(nsLength + localPart.length() + 2);
buffer.append('{');
buffer.append(namespaceURI);
buffer.append('}');
buffer.append(localPart);
_qNameAsString = buffer.toString();
}
qNameAsString = _qNameAsString;
}
return _qNameAsString;
}
/**
* 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 qNameAsString String representation
* of the QName
* @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);
}
/*
* For old versions of QName which didn't have a prefix field,
* ObjectInputStream.defaultReadObject() will initialize
* the prefix to null instead of the empty string. This
* method fixes up the prefix field if it didn't exist in the serialized
* object.
*/
private void readObject(ObjectInputStream in)
throws IOException, ClassNotFoundException {
in.defaultReadObject();
if (prefix == null) {
prefix = XMLConstants.DEFAULT_NS_PREFIX;
}
}
}