org.apache.commons.digester
public abstract class Rule extends Object
Writing a custom Rule is considered perfectly normal when using Digester, and is encouraged whenever the default set of Rule classes don't meet your requirements; the digester framework can help process xml even when the built-in rules aren't quite what is needed. Creating a custom Rule is just as easy as subclassing javax.servlet.http.HttpServlet for webapps, or javax.swing.Action for GUI applications.
If a rule wishes to manipulate a digester stack (the default object stack, a named stack, or the parameter stack) then it should only ever push objects in the rule's begin method and always pop exactly the same number of objects off the stack during the rule's end method. Of course peeking at the objects on the stacks can be done from anywhere.
Rule objects should be stateless, ie they should not update any instance member during the parsing process. A rule instance that changes state will encounter problems if invoked in a "nested" manner; this can happen if the same instance is added to digester multiple times or if a wildcard pattern is used which can match both an element and a child of the same element. The digester object stack and named stacks should be used to store any state that a rule requires, making the rule class safe under all possible uses.
Field Summary | |
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protected Digester | digester
The Digester with which this Rule is associated. |
protected String | namespaceURI
The namespace URI for which this Rule is relevant, if any. |
Constructor Summary | |
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Rule(Digester digester)
Constructor sets the associated Digester.
| |
Rule() Base constructor. |
Method Summary | |
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void | begin(Attributes attributes)
This method is called when the beginning of a matching XML element
is encountered.
|
void | begin(String namespace, String name, Attributes attributes)
This method is called when the beginning of a matching XML element
is encountered. |
void | body(String text)
This method is called when the body of a matching XML element
is encountered. |
void | body(String namespace, String name, String text)
This method is called when the body of a matching XML element is
encountered. |
void | end()
This method is called when the end of a matching XML element
is encountered.
|
void | end(String namespace, String name)
This method is called when the end of a matching XML element
is encountered. |
void | finish()
This method is called after all parsing methods have been
called, to allow Rules to remove temporary data. |
Digester | getDigester()
Return the Digester with which this Rule is associated. |
String | getNamespaceURI()
Return the namespace URI for which this Rule is relevant, if any. |
void | setDigester(Digester digester)
Set the Digester with which this Rule is associated. |
void | setNamespaceURI(String namespaceURI)
Set the namespace URI for which this Rule is relevant, if any.
|
Deprecated: The digester instance is now set in the Digester method. Use Rule instead.
Constructor sets the associated Digester.Parameters: digester The digester with which this rule is associated
Base constructor. Now the digester will be set when the rule is added.
Deprecated: Use the begin
method with namespace
and name
parameters instead.
Parameters: attributes The attribute list of this element
begin
without the
namespace
and name
parameters, to retain
backwards compatibility.
Parameters: namespace the namespace URI of the matching element, or an empty string if the parser is not namespace aware or the element has no namespace name the local name if the parser is namespace aware, or just the element name otherwise attributes The attribute list of this element
Since: Digester 1.4
Deprecated: Use the body
method
with namespace
and name
parameters
instead.
Parameters: text The text of the body of this element
The default implementation delegates to the deprecated method
body
without the namespace
and
name
parameters, to retain backwards compatibility.
Parameters: namespace the namespace URI of the matching element, or an empty string if the parser is not namespace aware or the element has no namespace name the local name if the parser is namespace aware, or just the element name otherwise text The text of the body of this element
Since: Digester 1.4
Deprecated: Use the end
method with
namespace
and name
parameters instead.
end
without the
namespace
and name
parameters, to retain
backwards compatibility.
Parameters: namespace the namespace URI of the matching element, or an empty string if the parser is not namespace aware or the element has no namespace name the local name if the parser is namespace aware, or just the element name otherwise
Since: Digester 1.4
Digester
with which this Rule
is associated.Parameters: namespaceURI Namespace URI for which this Rule is relevant,
or null
to match independent of namespace.