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This class encapsulates the logic of Namespace processing: it tracks the declarations currently in force for each context and automatically processes qualified XML 1.0 names into their Namespace parts; it can also be used in reverse for generating XML 1.0 from Namespaces.

Namespace support objects are reusable, but the reset method must be invoked between each session.

Here is a simple session:

 String parts[] = new String[3];
 NamespaceSupport support = new NamespaceSupport();
 support.pushContext();
 support.declarePrefix("", "http://www.w3.org/1999/xhtml");
 support.declarePrefix("dc", "http://www.purl.org/dc#");
 parts = support.processName("p", parts, false);
 System.out.println("Namespace URI: " + parts[0]);
 System.out.println("Local name: " + parts[1]);
 System.out.println("Raw name: " + parts[2]);
 parts = support.processName("dc:title", parts, false);
 System.out.println("Namespace URI: " + parts[0]);
 System.out.println("Local name: " + parts[1]);
 System.out.println("Raw name: " + parts[2]);
 support.popContext();
 

Note that this class is optimized for the use case where most elements do not contain Namespace declarations: if the same prefix/URI mapping is repeated for each context (for example), this class will be somewhat less efficient.

Although SAX drivers (parsers) may choose to use this class to implement namespace handling, they are not required to do so. Applications must track namespace information themselves if they want to use namespace information.
since:
   SAX 2.0
author:
   David Megginson
version:
   2.0.1 (sax2r2)

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 NamespaceSupport.getPrefixes method instead.

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

This method returns prefixes mapped to a specific Namespace URI.

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

Normally, you should pop the context at the end of each XML element.

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.

Event callback code should start a new context once per element. This means being ready to call this in either of two places. For elements that don't include namespace declarations, the ContentHandler.startElement() callback is the right place. For elements with such a declaration, it'd done in the first ContentHandler.startPrefixMapping() callback. A boolean flag can be used to track whether a context has been started yet.

This is the Namespace URI that is automatically mapped to the "xml" 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 the default element Namespace, use the empty string as the prefix.

Note that you must not declare a prefix after you've pushed and popped another Namespace context, or treated the declarations phase as complete by processing a prefixed name.

Note that there is an asymmetry in this library: NamespaceSupport.getPrefix getPrefix will not return the "" prefix, even if you have declared a default element namespace. To check for a default namespace, you have to look it up explicitly using NamespaceSupport.getURI getURI . This asymmetry exists to make it easier to look up prefixes for attribute names, where the default prefix is not allowed.

The empty (default) prefix will be included in this enumeration; note that this behaviour differs from that of NamespaceSupport.getPrefix and NamespaceSupport.getPrefixes .

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 NamespaceSupport.getPrefixes method instead.

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

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

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 NamespaceSupport.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 NamespaceSupport.getURI getURI method with an argument of "".

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

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.

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 attribute name will not.

Event callback code should start a new context once per element. This means being ready to call this in either of two places. For elements that don't include namespace declarations, the ContentHandler.startElement() callback is the right place. For elements with such a declaration, it'd done in the first ContentHandler.startPrefixMapping() callback. A boolean flag can be used to track whether a context has been started yet. When either of those methods is called, it checks the flag to see if a new context needs to be started. If so, it starts the context and sets the flag. After ContentHandler.startElement() does that, it always clears the flag.

Normally, SAX drivers would push a new context at the beginning of each XML element. Then they perform a first pass over the attributes to process all namespace declarations, making ContentHandler.startPrefixMapping() callbacks. Then a second pass is made, to determine the namespace-qualified names for all attributes and for the element name. Finally all the information for the ContentHandler.startElement() callback is available, so it can then be made.

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

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