NamespaceSupport

public class NamespaceSupport extends Object

Encapsulate Namespace logic for use by applications using SAX, or internally by SAX drivers.

This module, both source code and documentation, is in the Public Domain, and comes with NO WARRANTY. See http://www.saxproject.org for further information.

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

Constant Summary

String NSDECL The namespace declaration URI as a constant.
String XMLNS The XML Namespace URI as a constant.

Public Constructor Summary

NamespaceSupport()
Create a new Namespace support object.

Public Method Summary

boolean
declarePrefix(String prefix, String uri)
Declare a Namespace prefix.
Enumeration
getDeclaredPrefixes()
Return an enumeration of all prefixes declared in this context.
String
getPrefix(String uri)
Return one of the prefixes mapped to a Namespace URI.
Enumeration
getPrefixes()
Return an enumeration of all prefixes whose declarations are active in the current context.
Enumeration
getPrefixes(String uri)
Return an enumeration of all prefixes for a given URI whose declarations are active in the current context.
String
getURI(String prefix)
Look up a prefix and get the currently-mapped Namespace URI.
boolean
isNamespaceDeclUris()
Returns true if namespace declaration attributes are placed into a namespace.
void
popContext()
Revert to the previous Namespace context.
String[]
processName(String qName, String[] parts, boolean isAttribute)
Process a raw XML qualified name, after all declarations in the current context have been handled by declarePrefix().
void
pushContext()
Start a new Namespace context.
void
reset()
Reset this Namespace support object for reuse.
void
setNamespaceDeclUris(boolean value)
Controls whether namespace declaration attributes are placed into the NSDECL namespace by processName().

Inherited Method Summary

Constants

public static final String NSDECL

The namespace declaration URI as a constant. The value is http://www.w3.org/xmlns/2000/, as defined in a backwards-incompatible erratum to the "Namespaces in XML" recommendation. Because that erratum postdated SAX2, SAX2 defaults to the original recommendation, and does not normally use this URI.

This is the Namespace URI that is optionally applied to xmlns and xmlns:* attributes, which are used to declare namespaces.

Constant Value: "http://www.w3.org/xmlns/2000/"

public static final String XMLNS

The XML Namespace URI as a constant. The value is http://www.w3.org/XML/1998/namespace as defined in the "Namespaces in XML" * recommendation.

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

Constant Value: "http://www.w3.org/XML/1998/namespace"

Public Constructors

public NamespaceSupport ()

Create a new Namespace support object.

Public Methods

public boolean declarePrefix (String prefix, String uri)

Declare a Namespace prefix. All prefixes must be declared before they are referenced. For example, a SAX driver (parser) would scan an element's attributes in two passes: first for namespace declarations, then a second pass using processName() to interpret prefixes against (potentially redefined) prefixes.

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: 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 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 the empty string to indicate the default element namespace. This may never have the value "xml" or "xmlns".
uri The Namespace URI to associate with the prefix.
Returns
  • true if the prefix was legal, false otherwise