net.jini.lookup.entry

Class UIDescriptor

java.lang.Object

net.jini.entry.AbstractEntry

net.jini.lookup.entry.UIDescriptor

All Implemented Interfaces:

Serializable, Cloneable, CloneableEntry, Entry

public class UIDescriptor
extends AbstractEntry

Entry that enables a UI for a service to be associated with the service in the attribute sets of the service item. UIDescriptor holds a marshalled UI factory object, as well as a role string, a sub-role string, and set of attributes that describe the UI generated by the factory.

Author:

Bill Venners

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
Set	attributes An unmodifiable set of objects that describe the UI generated by the marshalled UI factory.
MarshalledObject	factory The get() method of this MarshalledObject must return an object that implements one or more UI factory interfaces.
String	role Gives the fully qualified name of the interface that represents the role of the UI generated by the marshalled UI factory.
String	toolkit A String to facilitate searching whose value represents the main UI toolkit (for example Swing or AWT) which the produced UI makes use of.

Constructor Summary

Constructors

Constructor and Description
UIDescriptor() Constructs a UIDescriptor with all fields set to null.
UIDescriptor(String role, String toolkit, Set attributes, MarshalledObject factory) Constructs a UIDescriptor with the fields set to passed values.

Method Summary

Modifier and Type	Method and Description
Object	getUIFactory(ClassLoader parentLoader) A convenience method for unmarshalling the UI factory stored in the MarshalledObject referenced from the factory field.

Methods inherited from class net.jini.entry.AbstractEntry

clone, equals, equals, hashCode, hashCode, toString, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

role

public String role

Gives the fully qualified name of the interface that represents the role of the UI generated by the marshalled UI factory. If the client program unmarshals the UI factory and invokes a factory method, the UI returned by the factory method must implement the role the interface specified by role.

For a client program to be able to use a UI, the client has to have prior knowledge of the UI semantics, which is defined by the UI's role type. Thus, for a client to be able to use a UI, the client must understand the semantics of the type whose fully qualified name is given in the String referenced from the role field of that UI's UIDescriptor.

For example, two role types that are defined in the net.jini.lookup.ui package by the Jini Service UI Specification are MainUI, for a main UI to a Jini service, and AdminUI, for an administration UI. Other role types may be defined by the Jini Service UI Specification and by individual Jini service API specifications.

As the strings referenced from the role field are Java type names, they are intended to be manipulated by client programs only. They should not be shown to a user.

toolkit

public String toolkit

A String to facilitate searching whose value represents the main UI toolkit (for example Swing or AWT) which the produced UI makes use of. The value to which this field should be set is defined by the semantics of the factory type. (This field is intended to facilitate searches. For example, a client can search for all blender services that have Swing MainUI's.)

attributes

public Set attributes

An unmodifiable set of objects that describe the UI generated by the marshalled UI factory.

factory

public MarshalledObject factory

The get() method of this MarshalledObject must return an object that implements one or more UI factory interfaces. The actual UI factory type or types implemented by the returned object must be described by a UIFactoryTypes attribute placed in the attributes set of this UIDescriptor.

Constructor Detail

UIDescriptor

public UIDescriptor()

Constructs a UIDescriptor with all fields set to null.

UIDescriptor

public UIDescriptor(String role,
                    String toolkit,
                    Set attributes,
                    MarshalledObject factory)

Constructs a UIDescriptor with the fields set to passed values. This constructor copies the contents of the passed attributes Set into a serializable read-only Set that has a consistent serialized form across all VMs, and initializes the attributes field with the consistent Set.

Parameters:

role - the role

toolkit - the toolkit

attributes - the attributes

factory - the factory

Method Detail

getUIFactory

public final Object getUIFactory(ClassLoader parentLoader)
                          throws IOException,
                                 ClassNotFoundException

A convenience method for unmarshalling the UI factory stored in the MarshalledObject referenced from the factory field. This method saves a reference to the current context class loader, sets the context class loader to the class loader passed as parentLoader, invokes get() on the marshalled object, then resets the context class loader to the saved reference before returning the object produced by get().

The class loader passed in parentLoader should be able to load classes needed when the UI interacts with the roleObject passed as the first parameter to the factory method. For example, if the roleObject is the service item (as it is for the MainUI and AdminUI roles), the class loader passed in parentLoader could be the class loader with which the service proxy object referenced from the service item's service field was loaded. For example:

 Object uiFactory = uiDescriptor.getUIFactory(
     serviceItem.service.getClass().getClassLoader());
 

Parameters:

parentLoader - the parent ClassLoader

Returns:

the unmarshalled UI factory

Throws:

IOException - if an IOException occurs

ClassNotFoundException - if class not found.

NullPointerException - if parentLoader is null.