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org.apache.commons.digester
abstract public class: Rule [javadoc | source]

java.lang.Object
   org.apache.commons.digester.Rule

Direct Known Subclasses:
    SetNestedPropertiesRule, BeanPropertySetterRule, ObjectCreateRule, SetPropertiesRule, DumperRule, FactoryCreateRule, PluginDeclarationRule, NodeCreateRule, SetRootRule, SetPropertiesAliasRule, AnyChildRule, TestRule, ObjectParamRule, CallMethodRule, PathCallParamRule, SetTopRule, SetPropertyRule, IncludeRule, PluginCreateRule, SetNextRule, SetNestedPropertiesAliasRule, PatternRule, CallParamRule

Concrete implementations of this class implement actions to be taken when a corresponding nested pattern of XML elements has been matched.

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
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:
public Rule() { } Base constructor. Now the digester will be set when the rule is added.
public Rule(Digester digester) { super(); setDigester(digester); } Constructor sets the associated Digester. Parameters: digester - The digester with which this rule is associated

Method from org.apache.commons.digester.Rule Summary:
begin,   begin,   body,   body,   end,   end,   finish,   getDigester,   getNamespaceURI,   setDigester,   setNamespaceURI

Methods from java.lang.Object:
equals,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait

Method from org.apache.commons.digester.Rule Detail:
public void begin(Attributes attributes) throws Exception { ; // The default implementation does nothing } Deprecated! Use - the begin method with namespace and name parameters instead. This method is called when the beginning of a matching XML element is encountered.
public void begin(String namespace, String name, Attributes attributes) throws Exception { begin(attributes); } This method is called when the beginning of a matching XML element is encountered. The default implementation delegates to the deprecated method begin without the namespace and name parameters, to retain backwards compatibility.
public void body(String text) throws Exception { ; // The default implementation does nothing } Deprecated! Use - the body method with namespace and name parameters instead. 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.
public void body(String namespace, String name, String text) throws Exception { body(text); } 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. The default implementation delegates to the deprecated method body without the namespace and name parameters, to retain backwards compatibility.
public void end() throws Exception { ; // The default implementation does nothing } Deprecated! Use - the end method with namespace and name parameters instead. This method is called when the end of a matching XML element is encountered.
public void end(String namespace, String name) throws Exception { end(); } This method is called when the end of a matching XML element is encountered. The default implementation delegates to the deprecated method end without the namespace and name parameters, to retain backwards compatibility.
public void finish() throws Exception { ; // The default implementation does nothing } This method is called after all parsing methods have been called, to allow Rules to remove temporary data.
public Digester getDigester() { // ------------------------------------------------------------- Properties return (this.digester); } Return the Digester with which this Rule is associated.
public String getNamespaceURI() { return (this.namespaceURI); } Return the namespace URI for which this Rule is relevant, if any.
public void setDigester(Digester digester) { this.digester = digester; } Set the Digester with which this Rule is associated.
public void setNamespaceURI(String namespaceURI) { this.namespaceURI = namespaceURI; } Set the namespace URI for which this Rule is relevant, if any.