org.apache.commons.digester.plugins

Class PluginCreateRule

public class PluginCreateRule extends Rule implements InitializableRule

Allows the original rules for parsing the configuration file to define points at which plugins are allowed, by configuring a PluginCreateRule with the appropriate pattern.

Since: 1.6

Field Summary
ClassbaseClass
A base class that any plugin must derive from.
DeclarationdefaultPlugin
Info about optional default plugin to be used if no plugin-id is specified in the input data.
PluginConfigurationExceptioninitException
Currently, none of the Rules methods allow exceptions to be thrown.
Stringpattern
In order to invoke the addRules method on the plugin class correctly, we need to know the pattern which this rule is matched by.
StringpluginClassAttr
StringpluginClassAttrNs
StringpluginIdAttr
StringpluginIdAttrNs
Constructor Summary
PluginCreateRule(Class baseClass)
Create a plugin rule where the user must specify a plugin-class or plugin-id.
PluginCreateRule(Class baseClass, Class dfltPluginClass)
Create a plugin rule where the user may specify a plugin.
PluginCreateRule(Class baseClass, Class dfltPluginClass, RuleLoader dfltPluginRuleLoader)
Create a plugin rule where the user may specify a plugin.
Method Summary
voidbegin(String namespace, String name, Attributes attributes)
Invoked when the Digester matches this rule against an xml element.
voidbody(String namespace, String name, String text)
Process the body text of this element.
voidend(String namespace, String name)
Invoked by the digester when the closing tag matching this Rule's pattern is encountered.
voidfireBeginMethods(List rules, String namespace, String name, Attributes list)
Duplicate the processing that the Digester does when firing the begin methods of rules.
voidfireBodyMethods(List rules, String namespaceURI, String name, String text)
Duplicate the processing that the Digester does when firing the body methods of rules.
voidfireEndMethods(List rules, String namespaceURI, String name)
Duplicate the processing that the Digester does when firing the end methods of rules.
StringgetPattern()
Return the pattern that this Rule is associated with.
voidpostRegisterInit(String matchPattern)
Invoked after this rule has been added to the set of digester rules, associated with the specified pattern.
voidsetPluginClassAttribute(String namespaceUri, String attrName)
Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which class should be instantiated.
voidsetPluginIdAttribute(String namespaceUri, String attrName)
Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which plugin declaration is being referenced.

Field Detail

baseClass

private Class baseClass
A base class that any plugin must derive from.

defaultPlugin

private Declaration defaultPlugin
Info about optional default plugin to be used if no plugin-id is specified in the input data. This can simplify the syntax where one particular plugin is usually used.

initException

private PluginConfigurationException initException
Currently, none of the Rules methods allow exceptions to be thrown. Therefore if this class cannot initialise itself properly, it cannot cause the digester to stop. Instead, we cache the exception and throw it the first time the begin() method is called.

pattern

private String pattern
In order to invoke the addRules method on the plugin class correctly, we need to know the pattern which this rule is matched by.

pluginClassAttr

private String pluginClassAttr

pluginClassAttrNs

private String pluginClassAttrNs

pluginIdAttr

private String pluginIdAttr

pluginIdAttrNs

private String pluginIdAttrNs

Constructor Detail

PluginCreateRule

public PluginCreateRule(Class baseClass)
Create a plugin rule where the user must specify a plugin-class or plugin-id.

Parameters: baseClass is the class which any specified plugin must be descended from.

PluginCreateRule

public PluginCreateRule(Class baseClass, Class dfltPluginClass)
Create a plugin rule where the user may specify a plugin. If the user doesn't specify a plugin, then the default class specified in this constructor is used.

Parameters: baseClass is the class which any specified plugin must be descended from. dfltPluginClass is the class which will be used if the user doesn't specify any plugin-class or plugin-id. This class will have custom rules installed for it just like a declared plugin.

PluginCreateRule

public PluginCreateRule(Class baseClass, Class dfltPluginClass, RuleLoader dfltPluginRuleLoader)
Create a plugin rule where the user may specify a plugin. If the user doesn't specify a plugin, then the default class specified in this constructor is used.

Parameters: baseClass is the class which any specified plugin must be descended from. dfltPluginClass is the class which will be used if the user doesn't specify any plugin-class or plugin-id. This class will have custom rules installed for it just like a declared plugin. dfltPluginRuleLoader is a RuleLoader instance which knows how to load the custom rules associated with this default plugin.

Method Detail

begin

public void begin(String namespace, String name, Attributes attributes)
Invoked when the Digester matches this rule against an xml element.

A new instance of the target class is created, and pushed onto the stack. A new "private" PluginRules object is then created and set as the digester's default Rules object. Any custom rules associated with the plugin class are then loaded into that new Rules object. Finally, any custom rules that are associated with the current pattern (such as SetPropertiesRules) have their begin methods executed.

Parameters: namespace name attributes

Throws: ClassNotFoundException PluginInvalidInputException PluginConfigurationException

body

public void body(String namespace, String name, String text)
Process the body text of this element.

Parameters: text The body text of this element

end

public void end(String namespace, String name)
Invoked by the digester when the closing tag matching this Rule's pattern is encountered.

Parameters: namespace Description of the Parameter name Description of the Parameter

Throws: Exception Description of the Exception

See Also: PluginCreateRule

fireBeginMethods

public void fireBeginMethods(List rules, String namespace, String name, Attributes list)
Duplicate the processing that the Digester does when firing the begin methods of rules. It would be really nice if the Digester class provided a way for this functionality to just be invoked directly.

fireBodyMethods

private void fireBodyMethods(List rules, String namespaceURI, String name, String text)
Duplicate the processing that the Digester does when firing the body methods of rules. It would be really nice if the Digester class provided a way for this functionality to just be invoked directly.

fireEndMethods

public void fireEndMethods(List rules, String namespaceURI, String name)
Duplicate the processing that the Digester does when firing the end methods of rules. It would be really nice if the Digester class provided a way for this functionality to just be invoked directly.

getPattern

public String getPattern()
Return the pattern that this Rule is associated with.

In general, Rule instances can be associated with multiple patterns. A PluginCreateRule, however, will only function correctly when associated with a single pattern. It is possible to fix this, but I can't be bothered just now because this feature is unlikely to be used.

Returns: The pattern value

postRegisterInit

public void postRegisterInit(String matchPattern)
Invoked after this rule has been added to the set of digester rules, associated with the specified pattern. Check all configuration data is valid and remember the pattern for later.

Parameters: matchPattern is the digester match pattern that is associated with this rule instance, eg "root/widget".

Throws: PluginConfigurationException

setPluginClassAttribute

public void setPluginClassAttribute(String namespaceUri, String attrName)
Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which class should be instantiated.

See PluginRules for more info.

setPluginIdAttribute

public void setPluginIdAttribute(String namespaceUri, String attrName)
Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which plugin declaration is being referenced.

See PluginRules for more info.

Copyright 2001-2005 The Apache Software Foundation.