// $Id: QName.java,v 1.10 2004/02/09 23:41:21 jsuttor Exp $
/*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.xml.namespace;
import java.io.Serializable;
import javax.xml.XMLConstants;
/**
* <p><code>QName</code> represents a <strong>qualified name</strong>
* as defined in the XML specifications: <a
* href="http://www.w3.org/TR/xmlschema-2/#QName">XML Schema Part2:
* Datatypes specification</a>, <a
* href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">Namespaces
* in XML</a>, <a
* href="http://www.w3.org/XML/xml-names-19990114-errata">Namespaces
* in XML Errata</a>.</p>
*
* <p>The value of a <code>QName</code> contains a <strong>Namespace
* URI</strong>, <strong>local part</strong> and
* <strong>prefix</strong>.</p>
*
* <p>The prefix is included in <code>QName</code> to retain lexical
* information <strong><em>when present</em></strong> in an {@link
* javax.xml.transform.Source XML input source}. The prefix is
* <strong><em>NOT</em></strong> used in {@link #equals(Object)
* QName.equals(Object)} or to compute the {@link #hashCode()
* QName.hashCode()}. Equality and the hash code are defined using
* <strong><em>only</em></strong> the Namespace URI and local part.</p>
*
* <p>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}.</p>
*
* <p><code>QName</code> is immutable.</p>
*
* @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
* @version $Revision: 1.10 $, $Date: 2004/02/09 23:41:21 $
* @see <a href="http://www.w3.org/TR/xmlschema-2/#QName">XML Schema Part2: Datatypes specification</a>
* @see <a href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">Namespaces in XML</a>
* @see <a href="http://www.w3.org/XML/xml-names-19990114-errata">Namespaces in XML Errata</a>
* @since 1.5
*/
public class QName implements Serializable {
/**
* <p>Stream Unique Identifier.</p>
*/
private static final long serialVersionUID = 4418622981026545151L;
/**
* <p>Namespace URI of this <code>QName</code>.</p>
*/
private final String namespaceURI;
/**
* <p>local part of this <code>QName</code>.</p>
*/
private final String localPart;
/**
* <p>prefix of this <code>QName</code>.</p>
*/
private final String prefix;
/**
* <p><code>QName</code> constructor specifying the Namespace URI
* and local part.</p>
*
* <p>If the Namespace URI is <code>null</code>, 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 <a
* href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">Namespaces
* in XML</a> 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.</p>
*
* <p>If the local part is <code>null</code> an
* <code>IllegalArgumentException</code> is thrown.
* A local part of "" is allowed to preserve
* compatible behavior with QName 1.0. </p>
*
* <p>When using this constructor, the prefix is set to {@link
* javax.xml.XMLConstants#DEFAULT_NS_PREFIX
* XMLConstants.DEFAULT_NS_PREFIX}.</p>
*
* <p>The Namespace URI is not validated as a
* <a href="http://www.ietf.org/rfc/rfc2396.txt">URI reference</a>.
* The local part is not validated as a
* <a href="http://www.w3.org/TR/REC-xml-names/#NT-NCName">NCName</a>
* as specified in <a href="http://www.w3.org/TR/REC-xml-names/">Namespaces
* in XML</a>.</p>
*
* @param namespaceURI Namespace URI of the <code>QName</code>
* @param localPart local part of the <code>QName</code>
*
* @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);
}
/**
* <p><code>QName</code> constructor specifying the Namespace URI,
* local part and prefix.</p>
*
* <p>If the Namespace URI is <code>null</code>, 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 <a
* href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">Namespaces
* in XML</a> 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.</p>
*
* <p>If the local part is <code>null</code> an
* <code>IllegalArgumentException</code> is thrown.
* A local part of "" is allowed to preserve
* compatible behavior with QName 1.0. </p>
*
* <p>If the prefix is <code>null</code>, an
* <code>IllegalArgumentException</code> 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.</p>
*
* <p>The Namespace URI is not validated as a
* <a href="http://www.ietf.org/rfc/rfc2396.txt">URI reference</a>.
* The local part and prefix are not validated as a
* <a href="http://www.w3.org/TR/REC-xml-names/#NT-NCName">NCName</a>
* as specified in <a href="http://www.w3.org/TR/REC-xml-names/">Namespaces
* in XML</a>.</p>
*
* @param namespaceURI Namespace URI of the <code>QName<code>
* @param localPart local part of the <code>QName<code>
* @param prefix prefix of the <code>QName<code>
*/
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;
}
/**
* <p><code>QName</code> constructor specifying the local part.</p>
*
* <p>If the local part is <code>null</code> an
* <code>IllegalArgumentException</code> is thrown.
* A local part of "" is allowed to preserve
* compatible behavior with QName 1.0. </p>
*
* <p>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}.</p>
*
* <p><em>In an XML context, all Element and Attribute names exist
* in the context of a Namespace. Making this explicit during the
* construction of a <code>QName</code> 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.</em></p>
*
* <p>The local part is not validated as a
* <a href="http://www.w3.org/TR/REC-xml-names/#NT-NCName">NCName</a>
* as specified in <a href="http://www.w3.org/TR/REC-xml-names/">Namespaces
* in XML</a>.</p>
*
* @param localPart local part of the <code>QName</code>
* @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);
}
/**
* <p>Get the Namespace URI of this <code>QName</code>.</p>
*
* @return Namespace URI of this <code>QName</code>
*/
public String getNamespaceURI() {
return namespaceURI;
}
/**
* <p>Get the local part of this <code>QName</code>.</p>
*
* @return local part of this <code>QName</code>
*/
public String getLocalPart() {
return localPart;
}
/**
* <p>Get the prefix of this <code>QName</code>.</p>
*
* <p>The prefix assigned to a <code>QName</code> might
* <strong><em>NOT</em></strong> be valid in a different
* context. For example, a <code>QName</code> 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.</p>
*
* @return prefix of this <code>QName</code>
*/
public String getPrefix() {
return prefix;
}
/**
* <p>Test this <code>QName</code> for equality with another
* <code>Object</code>.</p>
*
* <p>If the <code>Object</code> to be tested is not a
* <code>QName</code> or is <code>null</code>, then this method
* returns <code>false</code>.</p>
*
* <p>Two <code>QName</code>s are considered equal if and only if
* both the Namespace URI and local part are equal. This method
* uses <code>String.equals()</code> to check equality of the
* Namespace URI and local part. The prefix is
* <strong><em>NOT</em></strong> used to determine equality.</p>
*
* <p>This method satisfies the general contract of {@link
* java.lang.Object#equals(Object) Object.equals(Object)}</p>
*
* @param objectToTest the <code>Object</code> to test for
* equality with this <code>QName</code>
* @return <code>true</code> if the given <code>Object</code> is
* equal to this <code>QName</code> else <code>false</code>
*/
public final boolean equals(Object objectToTest) {
if (objectToTest == null || !(objectToTest instanceof QName)) {
return false;
}
QName qName = (QName) objectToTest;
return namespaceURI.equals(qName.namespaceURI)
&& localPart.equals(qName.localPart);
}
/**
* <p>Generate the hash code for this <code>QName</code>.</p>
*
* <p>The hash code is calculated using both the Namespace URI and
* the local part of the <code>QName</code>. The prefix is
* <strong><em>NOT</em></strong> used to calculate the hash
* code.</p>
*
* <p>This method satisfies the general contract of {@link
* java.lang.Object#hashCode() Object.hashCode()}.</p>
*
* @return hash code for this <code>QName</code> <code>Object</code>
*/
public final int hashCode() {
return namespaceURI.hashCode() ^ localPart.hashCode();
}
/**
* <p><code>String</code> representation of this
* <code>QName</code>.</p>
*
* <p>The commonly accepted way of representing a <code>QName</code>
* as a <code>String</code> was <a href="http://jclark.com/xml/xmlns.htm">defined</a>
* by James Clark. Although this is not a <em>standard</em>
* specification, it is in common use, e.g. {@link javax.xml.transform.Transformer#setParameter(String name, Object value)}.
* This implementation represents a <code>QName</code> as:
* "{" + Namespace URI + "}" + local part. If the Namespace URI
* <code>.equals(XMLConstants.NULL_NS_URI)</code>, only the
* local part is returned. An appropriate use of this method is
* for debugging or logging for human consumption.</p>
*
* <p>Note the prefix value is <strong><em>NOT</em></strong>
* returned as part of the <code>String</code> representation.</p>
*
* <p>This method satisfies the general contract of {@link
* java.lang.Object#toString() Object.toString()}.</p>
*
* @return <code>String</code> representation of this <code>QName</code>
*/
public String toString() {
if (namespaceURI.equals(XMLConstants.NULL_NS_URI)) {
return localPart;
} else {
return "{" + namespaceURI + "}" + localPart;
}
}
/**
* <p><code>QName</code> derived from parsing the formatted
* <code>String</code>.</p>
*
* <p>If the <code>String</code> is <code>null</code> or does not conform to
* {@link #toString() QName.toString()} formatting, an
* <code>IllegalArgumentException</code> is thrown.</p>
*
* <p><em>The <code>String</code> <strong>MUST</strong> be in the
* form returned by {@link #toString() QName.toString()}.</em></p>
* <p>The commonly accepted way of representing a <code>QName</code>
* as a <code>String</code> was <a href="http://jclark.com/xml/xmlns.htm">defined</a>
* by James Clark. Although this is not a <em>standard</em>
* specification, it is in common use, e.g. {@link javax.xml.transform.Transformer#setParameter(String name, Object value)}.
* This implementation parses a <code>String</code> formatted
* as: "{" + Namespace URI + "}" + local part. If the Namespace
* URI <code>.equals(XMLConstants.NULL_NS_URI)</code>, only the
* local part should be provided.</p>
*
* <p>The prefix value <strong><em>CANNOT</em></strong> be
* represented in the <code>String</code> and will be set to
* {@link javax.xml.XMLConstants#DEFAULT_NS_PREFIX
* XMLConstants.DEFAULT_NS_PREFIX}.</p>
*
* <p>This method does not do full validation of the resulting
* <code>QName</code>.
* <p>The Namespace URI is not validated as a
* <a href="http://www.ietf.org/rfc/rfc2396.txt">URI reference</a>.
* The local part is not validated as a
* <a href="http://www.w3.org/TR/REC-xml-names/#NT-NCName">NCName</a>
* as specified in
* <a href="http://www.w3.org/TR/REC-xml-names/">Namespaces in XML</a>.</p>
*
* @param qNameAsString <code>String</code> representation
* of the <code>QName</code>
* @return <code>QName</code> corresponding to the given <code>String</code>
* @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);
}
}
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