org.drombler.commons.context

Class LocalProxyContext

java.lang.Object

org.drombler.commons.context.LocalProxyContext

All Implemented Interfaces:

Context

public class LocalProxyContext
extends Object
implements Context

A proxy for local contexts to handle implicit and explicit local contexts. The explicit local context is provided by a LocalContextProvider. Implicit local contexts may be provided by frameworks to associate additional content with an object.

Author:

puce

See Also:

createLocalProxyContext(java.lang.Object)

Method Summary

Modifier and Type	Method and Description
<T> void	addContextListener(Class<T> type, ContextListener<T> listener) Registers a ContextListener for a specified type.
static LocalProxyContext	createLocalProxyContext(Object obj) Creates a new instance of this class for a given object.
<T> T	find(Class<T> type) Finds an instance of the specified type in this context.
<T> Collection<? extends T>	findAll(Class<T> type) Finds all instances of the specified type in this context.
Context	getExplicitContext() Gets the explicit context (provided by a LocalContextProvider.
ProxyContext	getImplicitContext() Gets the implicit proxy context.
boolean	hasExplicitContext() Indicates if this local context has an explicit context (provided by a LocalContextProvider.
boolean	hasImplicitContext() Indicates if this local context has some implicit contexts.
<T> void	removeContextListener(Class<T> type, ContextListener<T> listener) Unregisters a ContextListener for a specified type.

Methods inherited from class java.lang.Object

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

Method Detail

find

public <T> T find(Class<T> type)

Finds an instance of the specified type in this context. If this context has more than one instance of the specified type, the first one found will be returned.

Specified by:

find in interface Context

Type Parameters:

T - the specified type

Parameters:

type - the specified type

Returns:

the first instance found in this context with the specified type, or null if no instance was found. TODO: return Optional?

findAll

public <T> Collection<? extends T> findAll(Class<T> type)

Finds all instances of the specified type in this context.

Specified by:

findAll in interface Context

Type Parameters:

T - the specified type

Parameters:

type - the specified type

Returns:

a collection with all instances found in this context with the specified type, or an empty collection if no instance was found TODO: return List instead of Collection?
TODO: return <T> instead of <? extends T>?

addContextListener

public <T> void addContextListener(Class<T> type,
                                   ContextListener<T> listener)

Registers a ContextListener for a specified type. The listener will be notified when instances of the specified type get added or removed.

Specified by:

addContextListener in interface Context

Type Parameters:

T - the specified type

Parameters:

type - the type to listen for

listener - the ContextListener

removeContextListener

public <T> void removeContextListener(Class<T> type,
                                      ContextListener<T> listener)

Unregisters a ContextListener for a specified type.

Specified by:

removeContextListener in interface Context

Type Parameters:

T - the specified type

Parameters:

type - the type to listen for

listener - the ContextListener

getImplicitContext

public ProxyContext getImplicitContext()

Gets the implicit proxy context.

Returns:

the implicit proxy context

getExplicitContext

public Context getExplicitContext()

Gets the explicit context (provided by a LocalContextProvider.

Returns:

the explicit context

hasImplicitContext

public boolean hasImplicitContext()

Indicates if this local context has some implicit contexts.

Returns:

true, if there are implicit contexts, else false.

hasExplicitContext

public boolean hasExplicitContext()

Indicates if this local context has an explicit context (provided by a LocalContextProvider.

Returns:

true, if this local context has an explicit context, else false.

createLocalProxyContext

public static LocalProxyContext createLocalProxyContext(Object obj)

Creates a new instance of this class for a given object. If the object is an instance of LocalContextProvider, the provided local context will be set as explicit context. Else an instance with no explicit context gets created.

Parameters:

obj - the given object.

Returns:

a LocalProxyContext for the given object