wt.clients.util
Class TaskDelegateFactory

java.lang.Object
  wt.clients.util.TaskDelegateFactory

public class TaskDelegateFactory

extends Object

Class TaskDelegateFactory is a utility class which contains factory methods for instantiating TaskDelegate objects. This class instantiates task delegate objects based upon either a given class or the class of a given object.

The TaskDelegateFactory assumes a specific naming convention when trying to instantiate a TaskDelegate for a given class or object. If the fully-qualified class of the business object for which to instantiate a delegate is mysite.mypackage.MyBusinessObject, this factory will attempt to find a task delegate class whose fully-qualified class name is mysite.clients.mypackage.MyBusinessObjectTaskDelegate. For example, when attempting to instantiate a task delegate for wt.doc.WTDocument objects, the factory will look for a class whose fully-qualified name is wt.clients.doc.WTDocument. Given the fully-qualified class name of apkg.bpkg.cpkg.dpkg.Eobject, this factory will follow the following search algorithm to try and find a corresponding task delegate class:

1. apkg.clients.bpkg.cpkg.dpkg.EobjectTaskDelegate
2. apkg.bpkg.clients.cpkg.dpkg.EobjectTaskDelegate
3. apkg.bpkg.cpkg.clients.dpkg.EobjectTaskDelegate
4. apkg.bpkg.cpkg.dpkg.clients.EobjectTaskDelegate

If no delegate is found using this algorithm, the same algorithm will be applied to the parent of the given class. If no delegate is found applying this algorithm to the parent class, the same algorithm will be applied to the interfaces implemented by the given class. The TaskDelegateFactory class together with the TaskDelegate class form in a system in which business objects can be created, updated, viewed and deleted without knowing the specific type of the business object. For example:

    public class MyDisplay extends Frame {
       ...
       public void handleViewEvent( Event evt ) {
          Object obj_to_view = evt.getSource();
          TaskDelegate delegate =
	               TaskDelegateFactory.instantiateTaskDelegate( obj_to_view );
		      if( delegate != null ) {
		         delegate.setParentApplet( getParentApplet() );
		         delegate.setParentFrame( this );
		         delegate.setObject( obj_to_view );

	         try {
  		      delegate.launchViewTask();
  		   } catch (TaskDelegateException tde) {
             // Handle Exception
 		   }
       }
       ...
    }
  

Supported API: true

Extendable: false

Field Summary

protected static boolean

VERBOSE

Constructor Summary

TaskDelegateFactory()

Method Summary

private static String	formClassName(StringTokenizer tokens, int index)
private static Class	formDelegateClass(Class object_class)
static TaskDelegate	instantiateTaskDelegate(Class object_class) Returns an instance of the TaskDelegate which is associated with the given class.
static TaskDelegate	instantiateTaskDelegate(Object obj) Returns an instance of the TaskDelegate which is associated with the given object.
static TaskDelegate	instantiateTaskDelegate(String class_name) Returns an instance of the TaskDelegate which is associated with the given string classname.
private static Class	loadClass(String name)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

VERBOSE

protected static boolean VERBOSE

Constructor Detail

TaskDelegateFactory

public TaskDelegateFactory()

Method Detail

instantiateTaskDelegate

public static TaskDelegate instantiateTaskDelegate(Object obj)

Returns an instance of the TaskDelegate which is associated with the given object. This method uses the class of the given object to search for a corresponding task delegate. Given an object whose fully-qualified class name is apkg.bpkg.cpkg.dpkg.Eobject, the following search path is used to search for a task delegate:

1. apkg.clients.bpkg.cpkg.dpkg.EobjectTaskDelegate
2. apkg.bpkg.clients.cpkg.dpkg.EobjectTaskDelegate
3. apkg.bpkg.cpkg.clients.dpkg.EobjectTaskDelegate
4. apkg.bpkg.cpkg.dpkg.clients.EobjectTaskDelegate

If no delegate is found using this algorithm, the same algorithm will be applied to the parent of the given class. If no delegate is found applying this algorithm to the parent class, the same algorithm will be applied to the interfaces implemented by the given class. If no such TaskDelegate class exists, null is returned.

Parameters:

obj - the Object for which a corresponding task delegate is returned

Returns:

the TaskDelegate object associated with the given object; if no such TaskDelegate is found, null is returned

instantiateTaskDelegate

public static TaskDelegate instantiateTaskDelegate(String class_name)

Returns an instance of the TaskDelegate which is associated with the given string classname. This method uses the class specified by the fully-qualified String classname to search for a corresponding task delegate. Given a String specifying the fully-qualified class name, apkg.bpkg.cpkg.dpkg.Eobject, the following search path is used to search for a task delegate:

1. apkg.clients.bpkg.cpkg.dpkg.EobjectTaskDelegate
2. apkg.bpkg.clients.cpkg.dpkg.EobjectTaskDelegate
3. apkg.bpkg.cpkg.clients.dpkg.EobjectTaskDelegate
4. apkg.bpkg.cpkg.dpkg.clients.EobjectTaskDelegate

If no delegate is found using this algorithm, the same algorithm will be applied to the parent of the given class. If no delegate is found applying this algorithm to the parent class, the same algorithm will be applied to the interfaces implemented by the given class. If no such TaskDelegate class exists, null is returned.

Parameters:

class_name - the String representation of the fully-qualified class for which a corresponding task delegate is returned

Returns:

the TaskDelegate object associated with the given object; if no such TaskDelegate is found, null is returned

instantiateTaskDelegate

public static TaskDelegate instantiateTaskDelegate(Class object_class)

Returns an instance of the TaskDelegate which is associated with the given class. Given a fully-qualified class name of apkg.bpkg.cpkg.dpkg.Eobject, the following search path is used to search for a task delegate:

1. apkg.clients.bpkg.cpkg.dpkg.EobjectTaskDelegate
2. apkg.bpkg.clients.cpkg.dpkg.EobjectTaskDelegate
3. apkg.bpkg.cpkg.clients.dpkg.EobjectTaskDelegate
4. apkg.bpkg.cpkg.dpkg.clients.EobjectTaskDelegate

If no delegate is found using this algorithm, the same algorithm will be applied to the parent of the given class. If no delegate is found applying this algorithm to the parent class, the same algorithm will be applied to the interfaces implemented by the given class. If no such TaskDelegate class exists, null is returned.

Parameters:

object_class - the Class for which a corresponding task delegate is returned

Returns:

the TaskDelegate object associated with the given class; if no such TaskDelegate is found, null is returned

formDelegateClass

private static Class formDelegateClass(Class object_class)

formClassName

private static String formClassName(StringTokenizer tokens,
                                    int index)

loadClass

private static Class loadClass(String name)
                        throws ClassFormatError,
                               ClassNotFoundException,
                               Exception

Throws:

ClassFormatError

ClassNotFoundException

Exception