org.apache.tools.ant
Class IntrospectionHelper

java.lang.Object
  |
  +--org.apache.tools.ant.IntrospectionHelper
All Implemented Interfaces:
BuildListener, java.util.EventListener

public final class IntrospectionHelper
extends java.lang.Object
implements BuildListener

Helper class that collects the methods a task or nested element holds to set attributes, create nested elements or hold PCDATA elements. The class is final as it has a private constructor.


Nested Class Summary
static class IntrospectionHelper.Creator
          creator - allows use of create/store external to IntrospectionHelper.
 
Method Summary
 void addText(Project project, java.lang.Object element, java.lang.String text)
          Adds PCDATA to an element, using the element's void addText(String) method, if it has one.
 void buildFinished(BuildEvent event)
          Clears all storage used by this class, including the static cache of helpers.
 void buildStarted(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 java.lang.Object createElement(Project project, java.lang.Object parent, java.lang.String elementName)
          Deprecated. This is not a namespace aware method.
 java.lang.reflect.Method getAddTextMethod()
          Returns the addText method when the introspected class supports nested text.
 java.util.Map getAttributeMap()
          Returns a read-only map of attributes supported by the introspected class.
 java.lang.reflect.Method getAttributeMethod(java.lang.String attributeName)
          Returns the setter method of a named attribute.
 java.util.Enumeration getAttributes()
          Returns an enumeration of the names of the attributes supported by the introspected class.
 java.lang.Class getAttributeType(java.lang.String attributeName)
          Returns the type of a named attribute.
 IntrospectionHelper.Creator getElementCreator(Project project, java.lang.String parentUri, java.lang.Object parent, java.lang.String elementName, UnknownElement ue)
          returns an object that creates and stores an object for an element of a parent.
 java.lang.reflect.Method getElementMethod(java.lang.String elementName)
          Returns the adder or creator method of a named nested element.
protected  java.lang.String getElementName(Project project, java.lang.Object element)
          Returns a description of the type of the given element in relation to a given project.
 java.lang.Class getElementType(java.lang.String elementName)
          Returns the type of a named nested element.
 java.util.List getExtensionPoints()
          Returns a read-only list of extension points supported by the introspected class.
static IntrospectionHelper getHelper(java.lang.Class c)
          Returns a helper for the given class, either from the cache or by creating a new instance.
static IntrospectionHelper getHelper(Project p, java.lang.Class c)
          Returns a helper for the given class, either from the cache or by creating a new instance.
 java.util.Map getNestedElementMap()
          Returns a read-only map of nested elements supported by the introspected class.
 java.util.Enumeration getNestedElements()
          Returns an enumeration of the names of the nested elements supported by the introspected class.
 boolean isContainer()
          Indicates whether the introspected class is a task container, supporting arbitrary nested tasks/types.
 boolean isDynamic()
          Indicates whether the introspected class is a dynamic one, supporting arbitrary nested elements and/or attributes.
 void messageLogged(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void setAttribute(Project p, java.lang.Object element, java.lang.String attributeName, java.lang.String value)
          Sets the named attribute in the given element, which is part of the given project.
 void storeElement(Project project, java.lang.Object parent, java.lang.Object child, java.lang.String elementName)
          Stores a named nested element using a storage method determined by the initial introspection.
 boolean supportsCharacters()
          Returns whether or not the introspected class supports PCDATA.
 boolean supportsNestedElement(java.lang.String elementName)
          Indicates if this element supports a nested element of the given name.
 boolean supportsNestedElement(java.lang.String parentUri, java.lang.String elementName)
          Indicate if this element supports a nested element of the given name.
 void targetFinished(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void targetStarted(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void taskFinished(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void taskStarted(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void throwNotSupported(Project project, java.lang.Object parent, java.lang.String elementName)
          Utility method to throw a NotSupported exception
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

getHelper

public static IntrospectionHelper getHelper(java.lang.Class c)
Returns a helper for the given class, either from the cache or by creating a new instance.

Parameters:
c - The class for which a helper is required. Must not be null.
Returns:
a helper for the specified class

getHelper

public static IntrospectionHelper getHelper(Project p,
                                            java.lang.Class c)
Returns a helper for the given class, either from the cache or by creating a new instance. The method will make sure the helper will be cleaned up at the end of the project, and only one instance will be created for each class.

Parameters:
p - the project instance.
c - The class for which a helper is required. Must not be null.
Returns:
a helper for the specified class

setAttribute

public void setAttribute(Project p,
                         java.lang.Object element,
                         java.lang.String attributeName,
                         java.lang.String value)
                  throws BuildException
Sets the named attribute in the given element, which is part of the given project.

Parameters:
p - The project containing the element. This is used when files need to be resolved. Must not be null.
element - The element to set the attribute in. Must not be null.
attributeName - The name of the attribute to set. Must not be null.
value - The value to set the attribute to. This may be interpreted or converted to the necessary type if the setter method doesn't just take a string. Must not be null.
Throws:
BuildException - if the introspected class doesn't support the given attribute, or if the setting method fails.

addText

public void addText(Project project,
                    java.lang.Object element,
                    java.lang.String text)
             throws BuildException
Adds PCDATA to an element, using the element's void addText(String) method, if it has one. If no such method is present, a BuildException is thrown if the given text contains non-whitespace.

Parameters:
project - The project which the element is part of. Must not be null.
element - The element to add the text to. Must not be null.
text - The text to add. Must not be null.
Throws:
BuildException - if non-whitespace text is provided and no method is available to handle it, or if the handling method fails.

throwNotSupported

public void throwNotSupported(Project project,
                              java.lang.Object parent,
                              java.lang.String elementName)
Utility method to throw a NotSupported exception

Parameters:
project - the Project instance.
parent - the object which doesn't support a requested element
elementName - the name of the Element which is trying to be created.

createElement

public java.lang.Object createElement(Project project,
                                      java.lang.Object parent,
                                      java.lang.String elementName)
                               throws BuildException
Deprecated. This is not a namespace aware method.

Creates a named nested element. Depending on the results of the initial introspection, either a method in the given parent instance or a simple no-arg constructor is used to create an instance of the specified element type.

Parameters:
project - Project to which the parent object belongs. Must not be null. If the resulting object is an instance of ProjectComponent, its Project reference is set to this parameter value.
parent - Parent object used to create the instance. Must not be null.
elementName - Name of the element to create an instance of. Must not be null.
Returns:
an instance of the specified element type
Throws:
BuildException - if no method is available to create the element instance, or if the creating method fails.

getElementCreator

public IntrospectionHelper.Creator getElementCreator(Project project,
                                                     java.lang.String parentUri,
                                                     java.lang.Object parent,
                                                     java.lang.String elementName,
                                                     UnknownElement ue)
returns an object that creates and stores an object for an element of a parent.

Parameters:
project - Project to which the parent object belongs.
parentUri - The namespace uri of the parent object.
parent - Parent object used to create the creator object to create and store and instance of a subelement.
elementName - Name of the element to create an instance of.
ue - The unknown element associated with the element.
Returns:
a creator object to create and store the element instance.

isDynamic

public boolean isDynamic()
Indicates whether the introspected class is a dynamic one, supporting arbitrary nested elements and/or attributes.

Returns:
true if the introspected class is dynamic; false otherwise.
Since:
Ant 1.6.3
See Also:
DynamicElement, DynamicElementNS

isContainer

public boolean isContainer()
Indicates whether the introspected class is a task container, supporting arbitrary nested tasks/types.

Returns:
true if the introspected class is a container; false otherwise.
Since:
Ant 1.6.3
See Also:
TaskContainer

supportsNestedElement

public boolean supportsNestedElement(java.lang.String elementName)
Indicates if this element supports a nested element of the given name.

Parameters:
elementName - the name of the nested element being checked
Returns:
true if the given nested element is supported

supportsNestedElement

public boolean supportsNestedElement(java.lang.String parentUri,
                                     java.lang.String elementName)
Indicate if this element supports a nested element of the given name.

Parameters:
parentUri - the uri of the parent
elementName - the name of the nested element being checked
Returns:
true if the given nested element is supported

storeElement

public void storeElement(Project project,
                         java.lang.Object parent,
                         java.lang.Object child,
                         java.lang.String elementName)
                  throws BuildException
Stores a named nested element using a storage method determined by the initial introspection. If no appropriate storage method is available, this method returns immediately.

Parameters:
project - Ignored in this implementation. May be null.
parent - Parent instance to store the child in. Must not be null.
child - Child instance to store in the parent. Should not be null.
elementName - Name of the child element to store. May be null, in which case this method returns immediately.
Throws:
BuildException - if the storage method fails.

getElementType

public java.lang.Class getElementType(java.lang.String elementName)
                               throws BuildException
Returns the type of a named nested element.

Parameters:
elementName - The name of the element to find the type of. Must not be null.
Returns:
the type of the nested element with the specified name. This will never be null.
Throws:
BuildException - if the introspected class does not support the named nested element.

getAttributeType

public java.lang.Class getAttributeType(java.lang.String attributeName)
                                 throws BuildException
Returns the type of a named attribute.

Parameters:
attributeName - The name of the attribute to find the type of. Must not be null.
Returns:
the type of the attribute with the specified name. This will never be null.
Throws:
BuildException - if the introspected class does not support the named attribute.

getAddTextMethod

public java.lang.reflect.Method getAddTextMethod()
                                          throws BuildException
Returns the addText method when the introspected class supports nested text.

Returns:
the method on this introspected class that adds nested text. Cannot be null.
Throws:
BuildException - if the introspected class does not support the nested text.
Since:
Ant 1.6.3

getElementMethod

public java.lang.reflect.Method getElementMethod(java.lang.String elementName)
                                          throws BuildException
Returns the adder or creator method of a named nested element.

Parameters:
elementName - The name of the attribute to find the setter method of. Must not be null.
Returns:
the method on this introspected class that adds or creates this nested element. Can be null when the introspected class is a dynamic configurator!
Throws:
BuildException - if the introspected class does not support the named nested element.
Since:
Ant 1.6.3

getAttributeMethod

public java.lang.reflect.Method getAttributeMethod(java.lang.String attributeName)
                                            throws BuildException
Returns the setter method of a named attribute.

Parameters:
attributeName - The name of the attribute to find the setter method of. Must not be null.
Returns:
the method on this introspected class that sets this attribute. This will never be null.
Throws:
BuildException - if the introspected class does not support the named attribute.
Since:
Ant 1.6.3

supportsCharacters

public boolean supportsCharacters()
Returns whether or not the introspected class supports PCDATA.

Returns:
whether or not the introspected class supports PCDATA.

getAttributes

public java.util.Enumeration getAttributes()
Returns an enumeration of the names of the attributes supported by the introspected class.

Returns:
an enumeration of the names of the attributes supported by the introspected class.
See Also:
getAttributeMap()

getAttributeMap

public java.util.Map getAttributeMap()
Returns a read-only map of attributes supported by the introspected class.

Returns:
an attribute name to attribute Class unmodifiable map. Can be empty, but never null.
Since:
Ant 1.6.3

getNestedElements

public java.util.Enumeration getNestedElements()
Returns an enumeration of the names of the nested elements supported by the introspected class.

Returns:
an enumeration of the names of the nested elements supported by the introspected class.
See Also:
getNestedElementMap()

getNestedElementMap

public java.util.Map getNestedElementMap()
Returns a read-only map of nested elements supported by the introspected class.

Returns:
a nested-element name to nested-element Class unmodifiable map. Can be empty, but never null.
Since:
Ant 1.6.3

getExtensionPoints

public java.util.List getExtensionPoints()
Returns a read-only list of extension points supported by the introspected class.

A task/type or nested element with void methods named add() or addConfigured(), taking a single class or interface argument, supports extensions point. This method returns the list of all these void add[Configured](type) methods.

Returns:
a list of void, single argument add() or addConfigured() Methods of all supported extension points. These methods are sorted such that if the argument type of a method derives from another type also an argument of a method of this list, the method with the most derived argument will always appear first. Can be empty, but never null.
Since:
Ant 1.6.3

getElementName

protected java.lang.String getElementName(Project project,
                                          java.lang.Object element)
Returns a description of the type of the given element in relation to a given project. This is used for logging purposes when the element is asked to cope with some data it has no way of handling.

Parameters:
project - The project the element is defined in. Must not be null.
element - The element to describe. Must not be null.
Returns:
a description of the element type

buildFinished

public void buildFinished(BuildEvent event)
Clears all storage used by this class, including the static cache of helpers.

Specified by:
buildFinished in interface BuildListener
Parameters:
event - Ignored in this implementation.
See Also:
BuildEvent.getException()

buildStarted

public void buildStarted(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
buildStarted in interface BuildListener
Parameters:
event - Ignored in this implementation.

targetStarted

public void targetStarted(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
targetStarted in interface BuildListener
Parameters:
event - Ignored in this implementation.
See Also:
BuildEvent.getTarget()

targetFinished

public void targetFinished(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
targetFinished in interface BuildListener
Parameters:
event - Ignored in this implementation.
See Also:
BuildEvent.getException()

taskStarted

public void taskStarted(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
taskStarted in interface BuildListener
Parameters:
event - Ignored in this implementation.
See Also:
BuildEvent.getTask()

taskFinished

public void taskFinished(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
taskFinished in interface BuildListener
Parameters:
event - Ignored in this implementation.
See Also:
BuildEvent.getException()

messageLogged

public void messageLogged(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
messageLogged in interface BuildListener
Parameters:
event - Ignored in this implementation.
See Also:
BuildEvent.getMessage(), BuildEvent.getPriority()


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