public class NamespaceSupport extends Object
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; 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); System.out.println("Local name: " + parts); System.out.println("Raw name: " + parts); parts = support.processName("dc:title", parts, false); System.out.println("Namespace URI: " + parts); System.out.println("Local name: " + parts); System.out.println("Raw name: " + parts); 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.
|Modifier and Type||Field and Description|
The namespace declaration URI as a constant.
The XML Namespace URI as a constant.
|Constructor and Description|
Create a new Namespace support object.
|Modifier and Type||Method and Description|
Declare a Namespace prefix.
Return an enumeration of all prefixes declared in this context.
Return one of the prefixes mapped to a Namespace URI.
Return an enumeration of all prefixes whose declarations are active in the current context.
Return an enumeration of all prefixes for a given URI whose declarations are active in the current context.
Look up a prefix and get the currently-mapped Namespace URI.
Returns true if namespace declaration attributes are placed into a namespace.
Revert to the previous Namespace context.
Process a raw XML qualified name, after all declarations in the current context have been handled by
Start a new Namespace context.
Reset this Namespace support object for reuse.
public static final String XMLNS
http://www.w3.org/XML/1998/namespaceas defined in the "Namespaces in XML" * recommendation.
This is the Namespace URI that is automatically mapped to the "xml" prefix.
public static final String NSDECL
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.
public void reset()
It is necessary to invoke this method before reusing the Namespace support object for a new session. If namespace declaration URIs are to be supported, that flag must also be set to a non-default value.
public void pushContext()
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.
public void popContext()
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.
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
This asymmetry exists to make it easier to look up prefixes
for attribute names, where the default prefix is not allowed.
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.
processName(java.lang.String, java.lang.String, boolean),
This method processes a raw XML qualified 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:
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 receive the default Namespace (if any), while an unprefixed attribute name will not.
qName- The XML qualified 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).
This method looks up the prefix in the current context. Use the empty string ("") for the default Namespace.
public Enumeration getPrefixes()
Note: if there is a default prefix, it will not be
returned in this enumeration; check for the default prefix
getURI with an argument of "".
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
Note: this will never return the empty (default) prefix;
to check for a default prefix, use the
method with an argument of "".
public Enumeration getPrefixes(String 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
Note: the empty (default) prefix is never included
in this enumeration; to check for the presence of a default
Namespace, use the
getURI method with an
argument of "".
public Enumeration getDeclaredPrefixes()
public void setNamespaceDeclUris(boolean value)
processName(). This may only be changed before any contexts have been pushed.
value- the namespace declaration attribute state. A value of true enables this feature, a value of false disables it.
IllegalStateException- when attempting to set this after any context has been pushed.
public boolean isNamespaceDeclUris()