org.xml.sax.helpers
Class NamespaceSupport

java.lang.Object
  |
  +--org.xml.sax.helpers.NamespaceSupport

public class NamespaceSupport

extends java.lang.Object

Encapsulate Namespace logic for use by SAX drivers.

This module, both source code and documentation, is in the Public Domain, and comes with NO WARRANTY.

This class encapsulates the logic of Namespace processing: it tracks the declarations currently in force for each context and automatically processing raw XML 1.0 names into their Namespace parts.

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#");

 String 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]);

 String 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.

Since:

SAX 2.0

Version:

2.0beta

Author:

David Megginson, sax@megginson.com

Field Summary

static java.lang.String

XMLNS The XML Namespace as a constant.

Constructor Summary

NamespaceSupport()
Create a new Namespace support object.

Method Summary

boolean	declarePrefix(java.lang.String prefix, java.lang.String uri) Declare a Namespace prefix.
java.util.Enumeration	getDeclaredPrefixes() Return an enumeration of all prefixes declared in this context.
java.util.Enumeration	getPrefixes() Return an enumeration of all prefixes currently declared.
java.lang.String	getURI(java.lang.String prefix) Look up a prefix and get the currently-mapped Namespace URI.
void	popContext() Revert to the previous Namespace context.
java.lang.String[]	processName(java.lang.String rawName, java.lang.String[] parts, boolean isAttribute) Process a raw XML 1.0 name.
void	pushContext() Start a new Namespace context.
void	reset() Reset this Namespace support object for reuse.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

XMLNS

public static final java.lang.String XMLNS

The XML Namespace as a constant.

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

Constructor Detail

NamespaceSupport

public NamespaceSupport()

Create a new Namespace support object.

Method Detail

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.

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:

popContext()

popContext

public void popContext()

Revert to the previous Namespace context.

Normally, you should pop the context at the end of each 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:

pushContext()

declarePrefix

public boolean declarePrefix(java.lang.String prefix,
                             java.lang.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.

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:

processName(java.lang.String, java.lang.String[], boolean)

processName

public java.lang.String[] processName(java.lang.String rawName,
                                      java.lang.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:

rawName - The raw XML 1.0 name to be processed.

parts - An 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:

declarePrefix(java.lang.String, java.lang.String), String.intern()

getURI

public java.lang.String getURI(java.lang.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:

getPrefixes()

getPrefixes

public java.util.Enumeration getPrefixes()

Return an enumeration of all prefixes currently declared.

Returns:

An enumeration of all prefixes declared in the current context.

See Also:

getDeclaredPrefixes(), getURI(java.lang.String)

getDeclaredPrefixes

public java.util.Enumeration getDeclaredPrefixes()

Return an enumeration of all prefixes declared in this context.

Returns:

An enumeration of all prefixes declared in this context.

See Also:

getPrefixes(), getURI(java.lang.String)