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.
| Modifier and Type | Class and Description |
|---|---|
| pack-priv class | NamespaceSupport.
Internal class for a single Namespace context. |
| Modifier and Type | Field and Description |
|---|---|
| private int | |
| private NamespaceSupport. | |
| private NamespaceSupport. | |
| private static final Enumeration | EMPTY_ENUMERATION
An empty enumeration. |
| private boolean | |
| public static final String | NSDECL
The namespace declaration URI as a constant. |
| public static final String | XMLNS
The XML Namespace URI as a constant. |
| Access | Constructor and Description |
|---|---|
| public |
| Modifier and Type | Method and Description |
|---|---|
| public boolean | Returns: true if the prefix was legal, false otherwiseThe prefix to declare, or the empty string to
indicate the default element namespace. This may never have
the value "xml" or "xmlns". prefix, String The Namespace URI to associate with the prefix. uri)Declare a Namespace prefix. |
| public Enumeration | Returns: An enumeration of all prefixes declared in this context.Return an enumeration of all prefixes declared in this context. |
| public String | |
| public Enumeration | Returns: An enumeration of prefixes (never empty).Return an enumeration of all prefixes whose declarations are active in the current context. |
| public Enumeration | Returns: An enumeration of prefixes (never empty).The Namespace URI. uri)Return an enumeration of all prefixes for a given URI whose declarations are active in the current context. |
| public String | |
| public boolean | Returns: true if namespace declaration attributes are placed into a namespace, false otherwiseReturns true if namespace declaration attributes are placed into a namespace. |
| public void | |
| public String[] | Returns: The supplied array holding three internalized strings representing the Namespace URI (or empty string), the local name, and the XML qualified name; or null if there is an undeclared prefix.The XML qualified name to be processed. qName, String[] An array supplied by the caller, capable of
holding at least three members. parts, boolean A flag indicating whether this is an
attribute name (true) or an element name (false). isAttribute)Process a raw XML qualified name, after all declarations in the
current context have been handled by |
| public void | |
| public void | |
| public void | setNamespaceDeclUris(boolean
a flag indicating whether namespace declaration attributes
are placed into the value)NSDECL namespaceControls whether namespace declaration attributes are placed
into the |
| contextPos | back to summary |
|---|---|
| private int contextPos | |
| contexts | back to summary |
|---|---|
| private NamespaceSupport. | |
| currentContext | back to summary |
|---|---|
| private NamespaceSupport. | |
| EMPTY_ENUMERATION | back to summary |
|---|---|
| private static final Enumeration<String> EMPTY_ENUMERATION An empty enumeration. | |
| namespaceDeclUris | back to summary |
|---|---|
| private boolean namespaceDeclUris | |
| NSDECL | back to summary |
|---|---|
| public static final String NSDECL The namespace declaration URI as a constant.
The value is This is the Namespace URI that is optionally applied to xmlns and xmlns:* attributes, which are used to declare namespaces.
| |
| XMLNS | back to summary |
|---|---|
| public static final String XMLNS The XML Namespace URI as a constant.
The value is This is the Namespace URI that is automatically mapped to the "xml" prefix. | |
| NamespaceSupport | back to summary |
|---|---|
| public NamespaceSupport() Create a new Namespace support object. | |
| declarePrefix | back to summary |
|---|---|
| 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 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 there is an asymmetry in this library:
| |
| getDeclaredPrefixes | back to summary |
|---|---|
| public Enumeration 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 | back to summary |
|---|---|
| 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 Note this will never return the empty (default) prefix;
to check for a default prefix, use the
| |
| getPrefixes | back to summary |
|---|---|
| public Enumeration Return an enumeration of all prefixes whose declarations are active in the current context. This includes declarations from parent contexts that have not been overridden. Note if there is a default prefix, it will not be
returned in this enumeration; check for the default prefix
using the
| |
| getPrefixes | back to summary |
|---|---|
| public Enumeration Return an enumeration of all prefixes for a given URI whose declarations are active in the current context. This includes declarations from parent contexts that have not been overridden. 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 | back to summary |
|---|---|
| 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.
| |
| isNamespaceDeclUris | back to summary |
|---|---|
| public boolean isNamespaceDeclUris() Returns true if namespace declaration attributes are placed into a namespace. This behavior is not the default.
| |
| popContext | back to summary |
|---|---|
| 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.
| |
| processName | back to summary |
|---|---|
| public 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 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.
| |
| pushContext | back to summary |
|---|---|
| public void pushContext() Start a new Namespace context. 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. 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.
| |
| reset | back to summary |
|---|---|
| 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. If namespace declaration URIs are to be supported, that flag must also be set to a non-default value.
| |
| setNamespaceDeclUris | back to summary |
|---|---|
| public void setNamespaceDeclUris(boolean value) Controls whether namespace declaration attributes are placed
into the
| |
This module caches and reuses Namespace contexts, so the number allocated will be equal to the element depth of the document, not to the total number of elements (i.e. 5-10 rather than tens of thousands). Also, data structures used to represent contexts are shared when possible (child contexts without declarations) to further reduce the amount of memory that's consumed.
| Modifier and Type | Field and Description |
|---|---|
| pack-priv Map | |
| private List | |
| private boolean | |
| pack-priv String | |
| pack-priv Map | |
| private NamespaceSupport. | |
| pack-priv Map | |
| pack-priv Map |
| Access | Constructor and Description |
|---|---|
| pack-priv |
| Modifier and Type | Method and Description |
|---|---|
| pack-priv void | |
| private void | |
| pack-priv void | declarePrefix(String
The prefix to declare. prefix, String The associated Namespace URI. uri)Declare a Namespace prefix for this context. |
| pack-priv Enumeration | Returns: An enumeration of prefixes (possibly empty).Return an enumeration of prefixes declared in this context. |
| pack-priv String | |
| pack-priv Enumeration | Returns: An enumeration of prefixes (never empty).Return an enumeration of all prefixes currently in force. |
| pack-priv String | |
| pack-priv String[] | Returns: An array of three strings containing the URI part (or empty string), the local part, and the raw name, all internalized, or null if there is an undeclared prefix.The XML qualified name. qName, boolean true if this is an attribute name. isAttribute)Process an XML qualified name in this context. |
| pack-priv void |
| attributeNameTable | back to summary |
|---|---|
| pack-priv Map<String, String[]> attributeNameTable | |
| declarations | back to summary |
|---|---|
| private List<String> declarations | |
| declSeen | back to summary |
|---|---|
| private boolean declSeen | |
| defaultNS | back to summary |
|---|---|
| pack-priv String defaultNS | |
| elementNameTable | back to summary |
|---|---|
| pack-priv Map<String, String[]> elementNameTable | |
| parent | back to summary |
|---|---|
| private NamespaceSupport. | |
| prefixTable | back to summary |
|---|---|
| pack-priv Map<String, String> prefixTable | |
| uriTable | back to summary |
|---|---|
| pack-priv Map<String, String> uriTable | |
| Context | back to summary |
|---|---|
| pack-priv Context() Create the root-level Namespace context. | |
| clear | back to summary |
|---|---|
| pack-priv void clear() Makes associated state become collectible,
invalidating this context.
| |
| copyTables | back to summary |
|---|---|
| private void copyTables() Copy on write for the internal tables in this context. This class is optimized for the normal case where most elements do not contain Namespace declarations. | |
| declarePrefix | back to summary |
|---|---|
| pack-priv void declarePrefix(String prefix, String uri) Declare a Namespace prefix for this context.
| |
| getDeclaredPrefixes | back to summary |
|---|---|
| pack-priv Enumeration Return an enumeration of prefixes declared in this context.
| |
| getPrefix | back to summary |
|---|---|
| pack-priv String getPrefix(String uri) Look up one of the prefixes associated with a URI in this context. Since many prefixes may be mapped to the same URI, the return value may be unreliable.
| |
| getPrefixes | back to summary |
|---|---|
| pack-priv Enumeration Return an enumeration of all prefixes currently in force. The default prefix, if in force, is not returned, and will have to be checked for separately.
| |
| getURI | back to summary |
|---|---|
| pack-priv String getURI(String prefix) Look up the URI associated with a prefix in this context.
| |
| processName | back to summary |
|---|---|
| pack-priv String[] processName(String qName, boolean isAttribute) Process an XML qualified name in this context.
| |
| setParent | back to summary |
|---|---|
| pack-priv void setParent(NamespaceSupport. (Re)set the parent of this Namespace context. The context must either have been freshly constructed, or must have been cleared. | |