Class Rule
- Direct Known Subclasses:
AbstractMethodRule
,BeanPropertySetterRule
,CallMethodRule
,CallParamRule
,FactoryCreateRule
,IncludeRule
,NodeCreateRule
,ObjectCreateRule
,ObjectParamRule
,PathCallParamRule
,PatternRule
,PluginCreateRule
,PluginDeclarationRule
,SetNamespaceURIRule
,SetNestedPropertiesAliasRule
,SetNestedPropertiesIgnoreRule
,SetNestedPropertiesRule
,SetNestedPropertiesRule.AnyChildRule
,SetPropertiesAliasRule
,SetPropertiesIgnoreRule
,SetPropertiesRule
,SetPropertyRule
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.
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Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
begin
(String namespace, String name, Attributes attributes) This method is called when the beginning of a matching XML element is encountered.void
This method is called when the body of a matching XML element is encountered.void
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.Return the Digester with which this Rule is associated.Return the namespace URI for which this Rule is relevant, if any.void
setDigester
(Digester digester) Set theDigester
with which thisRule
is associated.void
setNamespaceURI
(String namespaceURI) Set the namespace URI for which this Rule is relevant, if any.
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Field Details
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digester
The Digester with which this Rule is associated. -
namespaceURI
The namespace URI for which this Rule is relevant, if any.
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Constructor Details
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Rule
public Rule()
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Method Details
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getDigester
Return the Digester with which this Rule is associated.- Returns:
- the Digester with which this Rule is associated
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setDigester
Set theDigester
with which thisRule
is associated.- Parameters:
digester
- theDigester
with which thisRule
is associated
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getNamespaceURI
Return the namespace URI for which this Rule is relevant, if any.- Returns:
- the namespace URI for which this Rule is relevant, if any
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setNamespaceURI
Set the namespace URI for which this Rule is relevant, if any.- Parameters:
namespaceURI
- Namespace URI for which this Rule is relevant, ornull
to match independent of namespace.
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begin
This method is called when the beginning of a matching XML element is encountered.- 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 namespacename
- the local name if the parser is namespace aware, or just the element name otherwiseattributes
- The attribute list of this element- Throws:
Exception
- if any error occurs- Since:
- Digester 1.4
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body
This method is called when the body of a matching XML element is encountered. If the element has no body, this method is called with an empty string as the body text.- 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 namespacename
- the local name if the parser is namespace aware, or just the element name otherwisetext
- The text of the body of this element- Throws:
Exception
- if any error occurs- Since:
- Digester 1.4
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end
This method is called when the end of a matching XML element is encountered.- 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 namespacename
- the local name if the parser is namespace aware, or just the element name otherwise- Throws:
Exception
- if any error occurs- Since:
- Digester 1.4
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finish
This method is called after all parsing methods have been called, to allow Rules to remove temporary data.- Throws:
Exception
- if any error occurs
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