org.apache.xml.utils

Class NamespaceSupport2

public class NamespaceSupport2 extends NamespaceSupport

Encapsulate Namespace tracking logic for use by SAX drivers.

This class is an attempt to rewrite the SAX NamespaceSupport "helper" class for improved efficiency. It can be used to track the namespace declarations currently in scope, providing lookup routines to map prefixes to URIs and vice versa.

ISSUE: For testing purposes, I've extended NamespaceSupport even though I'm completely reasserting all behaviors and fields. Wasteful.... But SAX did not put an interface under that object and we seem to have written that SAX class into our APIs... and I don't want to argue with it right now.

See Also: org.xml.sax.helpers.NamespaceSupport

Field Summary
static StringXMLNS
The XML Namespace as a constant.
Constructor Summary
NamespaceSupport2()
Create a new Namespace support object.
Method Summary
booleandeclarePrefix(String prefix, String uri)
Declare a Namespace prefix.
EnumerationgetDeclaredPrefixes()
Return an enumeration of all prefixes declared in this context.
StringgetPrefix(String uri)
Return one of the prefixes mapped to a Namespace URI.
EnumerationgetPrefixes()
Return an enumeration of all prefixes currently declared.
EnumerationgetPrefixes(String uri)
Return an enumeration of all prefixes currently declared for a URI.
StringgetURI(String prefix)
Look up a prefix and get the currently-mapped Namespace URI.
voidpopContext()
Revert to the previous Namespace context.
String[]processName(String qName, String[] parts, boolean isAttribute)
Process a raw XML 1.0 name.
voidpushContext()
Start a new Namespace context.
voidreset()
Reset this Namespace support object for reuse.

Field Detail

XMLNS

public static final String XMLNS
The XML Namespace as a constant.

This is the Namespace URI that is automatically mapped to the "xml" prefix.

Constructor Detail

NamespaceSupport2

public NamespaceSupport2()
Create a new Namespace support object.

Method Detail

declarePrefix

public boolean declarePrefix(String prefix, String uri)
Declare a Namespace prefix.

This method declares a prefix in the current Namespace context; the prefix will remain in force until this context is popped, unless it is shadowed in a descendant context.

To declare a default Namespace, use the empty string. The prefix must not be "xml" or "xmlns".

Note that you must not declare a prefix after you've pushed and popped another Namespace.

Note that there is an asymmetry in this library: while {@link #getPrefix getPrefix} will not return the default "" prefix, even if you have declared one; to check for a default prefix, you have to look it up explicitly using {@link #getURI getURI}. This asymmetry exists to make it easier to look up prefixes for attribute names, where the default prefix is not allowed.

Parameters: prefix The prefix to declare, or null for the empty string. uri The Namespace URI to associate with the prefix.

Returns: true if the prefix was legal, false otherwise

See Also: NamespaceSupport2 NamespaceSupport2 NamespaceSupport2

getDeclaredPrefixes

public Enumeration getDeclaredPrefixes()
Return an enumeration of all prefixes declared in this context.

The empty (default) prefix will be included in this enumeration; note that this behaviour differs from that of {@link #getPrefix} and {@link #getPrefixes}.

Returns: An enumeration of all prefixes declared in this context.

See Also: NamespaceSupport2 NamespaceSupport2

getPrefix

public String getPrefix(String uri)
Return one of the prefixes mapped to a Namespace URI.

If more than one prefix is currently mapped to the same URI, this method will make an arbitrary selection; if you want all of the prefixes, use the {@link #getPrefixes} method instead.

Note: this will never return the empty (default) prefix; to check for a default prefix, use the {@link #getURI getURI} method with an argument of "".

Parameters: uri The Namespace URI.

Returns: One of the prefixes currently mapped to the URI supplied, or null if none is mapped or if the URI is assigned to the default Namespace.

See Also: NamespaceSupport2 NamespaceSupport2

getPrefixes

public Enumeration getPrefixes()
Return an enumeration of all prefixes currently declared.

Note: if there is a default prefix, it will not be returned in this enumeration; check for the default prefix using the {@link #getURI getURI} with an argument of "".

Returns: An enumeration of all prefixes declared in the current context except for the empty (default) prefix.

See Also: NamespaceSupport2 NamespaceSupport2

getPrefixes

public Enumeration getPrefixes(String uri)
Return an enumeration of all prefixes currently declared for a URI.

This method returns prefixes mapped to a specific Namespace URI. The xml: prefix will be included. If you want only one prefix that's mapped to the Namespace URI, and you don't care which one you get, use the {@link #getPrefix getPrefix} method instead.

Note: the empty (default) prefix is never included in this enumeration; to check for the presence of a default Namespace, use the {@link #getURI getURI} method with an argument of "".

Parameters: uri The Namespace URI.

Returns: An enumeration of all prefixes declared in the current context.

See Also: NamespaceSupport2 NamespaceSupport2 NamespaceSupport2

getURI

public String getURI(String prefix)
Look up a prefix and get the currently-mapped Namespace URI.

This method looks up the prefix in the current context. Use the empty string ("") for the default Namespace.

Parameters: prefix The prefix to look up.

Returns: The associated Namespace URI, or null if the prefix is undeclared in this context.

See Also: NamespaceSupport2 NamespaceSupport2

popContext

public void popContext()
Revert to the previous Namespace context.

Normally, you should pop the context at the end of each XML element. After popping the context, all Namespace prefix mappings that were previously in force are restored.

You must not attempt to declare additional Namespace prefixes after popping a context, unless you push another context first.

See Also: NamespaceSupport2

processName

public String[] processName(String qName, String[] parts, boolean isAttribute)
Process a raw XML 1.0 name.

This method processes a raw XML 1.0 name in the current context by removing the prefix and looking it up among the prefixes currently declared. The return value will be the array supplied by the caller, filled in as follows:

parts[0]
The Namespace URI, or an empty string if none is in use.
parts[1]
The local name (without prefix).
parts[2]
The original raw name.

All of the strings in the array will be internalized. If the raw name has a prefix that has not been declared, then the return value will be null.

Note that attribute names are processed differently than element names: an unprefixed element name will received the default Namespace (if any), while an unprefixed element name will not.

Parameters: qName The raw XML 1.0 name to be processed. parts A string array supplied by the caller, capable of holding at least three members. isAttribute A flag indicating whether this is an attribute name (true) or an element name (false).

Returns: The supplied array holding three internalized strings representing the Namespace URI (or empty string), the local name, and the raw XML 1.0 name; or null if there is an undeclared prefix.

See Also: NamespaceSupport2 java.lang.String#intern

pushContext

public void pushContext()
Start a new Namespace context.

Normally, you should push a new context at the beginning of each XML element: the new context will automatically inherit the declarations of its parent context, but it will also keep track of which declarations were made within this context.

The Namespace support object always starts with a base context already in force: in this context, only the "xml" prefix is declared.

See Also: NamespaceSupport2

reset

public void reset()
Reset this Namespace support object for reuse.

It is necessary to invoke this method before reusing the Namespace support object for a new session.

Copyright © 2005 Apache XML Project. All Rights Reserved.