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 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#");
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.
Version:
- David Megginson,
sax@megginson.com
- SAX 2.0
static String | XMLNS - The XML Namespace as a constant.
|
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 currently declared.
|
Enumeration | getPrefixes(String uri) - Return an enumeration of all prefixes currently declared for a URI.
|
String | getURI(String prefix) - Look up a prefix and get the currently-mapped Namespace URI.
|
void | popContext() - Revert to the previous Namespace context.
|
String[] | processName(String qName, 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.
|
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.
NamespaceSupport
public NamespaceSupport()
Create a new Namespace support object.
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
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
getURI
.
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 null for the empty
string.uri
- The Namespace URI to associate with the prefix.
- true if the prefix was legal, false otherwise
processName(String,parts[],boolean)
, getURI(String)
, getPrefix(String)
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
getPrefix(String)
and
getPrefixes
.
- An enumeration of all prefixes declared in this
context.
getPrefixes
, getURI(String)
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
getPrefixes
method instead.
Note: this will never return the empty (default) prefix;
to check for a default prefix, use the
getURI
method with an argument of "".
uri
- The Namespace URI.
- 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.
getPrefixes(java.lang.String)
, getURI(String)
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
getURI
with an argument of "".
- An enumeration of all prefixes declared in the
current context except for the empty (default)
prefix.
getDeclaredPrefixes()
, getURI(String)
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
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
getURI
method with an
argument of "".
uri
- The Namespace URI.
- An enumeration of all prefixes declared in the
current context.
getPrefix(String)
, getDeclaredPrefixes()
, getURI(String)
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.
prefix
- The prefix to look up.
- The associated Namespace URI, or null if the prefix
is undeclared in this context.
getPrefix(String)
, getPrefixes
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.
pushContext()
processName
public String[] processName(String qName,
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.
qName
- The raw XML 1.0 name to be processed.isAttribute
- A flag indicating whether this is an
attribute name (true) or an element name (false).
- 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.
declarePrefix(String,String)
, 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.
popContext()
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.