org.springframework.web.context.support
Class ServletContextScope

java.lang.Object
  org.springframework.web.context.support.ServletContextScope

All Implemented Interfaces:

Scope, DisposableBean

public class ServletContextScope
extends Object
implements Scope, DisposableBean

Scope wrapper for a ServletContext, i.e. for global web application attributes.

This differs from traditional Spring singletons in that it exposes attributes in the ServletContext. Those attributes will get destroyed whenever the entire application shuts down, which might be earlier or later than the shutdown of the containing Spring ApplicationContext.

The associated destruction mechanism relies on a ContextCleanupListener being registered in web.xml. Note that ContextLoaderListener includes ContextCleanupListener's functionality.

This scope is registered as default scope with key "application".

Since:

3.0

Author:

Juergen Hoeller

See Also:

ContextCleanupListener

Constructor Summary

ServletContextScope(ServletContext servletContext)
Create a new Scope wrapper for the given ServletContext.

Method Summary

void	destroy() Invoke all registered destruction callbacks.
Object	get(String name, ObjectFactory<?> objectFactory) Return the object with the given name from the underlying scope, creating it if not found in the underlying storage mechanism.
String	getConversationId() Return the conversation ID for the current underlying scope, if any.
void	registerDestructionCallback(String name, Runnable callback) Register a callback to be executed on destruction of the specified object in the scope (or at destruction of the entire scope, if the scope does not destroy individual objects but rather only terminates in its entirety).
Object	remove(String name) Remove the object with the given name from the underlying scope.
Object	resolveContextualObject(String key) Resolve the contextual object for the given key, if any.

Methods inherited from class java.lang.Object

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

Constructor Detail

ServletContextScope

public ServletContextScope(ServletContext servletContext)

Create a new Scope wrapper for the given ServletContext.

Parameters:

servletContext - the ServletContext to wrap

Method Detail

get

public Object get(String name,
                  ObjectFactory<?> objectFactory)

Description copied from interface: Scope

Return the object with the given name from the underlying scope, creating it if not found in the underlying storage mechanism.

This is the central operation of a Scope, and the only operation that is absolutely required.

Specified by:

get in interface Scope

Parameters:

name - the name of the object to retrieve

objectFactory - the ObjectFactory to use to create the scoped object if it is not present in the underlying storage mechanism

Returns:

the desired object (never null)

remove

public Object remove(String name)

Description copied from interface: Scope

Remove the object with the given name from the underlying scope.

Returns null if no object was found; otherwise returns the removed Object.

Note that an implementation should also remove a registered destruction callback for the specified object, if any. It does, however, not need to execute a registered destruction callback in this case, since the object will be destroyed by the caller (if appropriate).

Note: This is an optional operation. Implementations may throw UnsupportedOperationException if they do not support explicitly removing an object.

Specified by:

remove in interface Scope

Parameters:

name - the name of the object to remove

Returns:

the removed object, or null if no object was present

See Also:

Scope.registerDestructionCallback(java.lang.String, java.lang.Runnable)

registerDestructionCallback

public void registerDestructionCallback(String name,
                                        Runnable callback)

Description copied from interface: Scope

Register a callback to be executed on destruction of the specified object in the scope (or at destruction of the entire scope, if the scope does not destroy individual objects but rather only terminates in its entirety).

Note: This is an optional operation. This method will only be called for scoped beans with actual destruction configuration (DisposableBean, destroy-method, DestructionAwareBeanPostProcessor). Implementations should do their best to execute a given callback at the appropriate time. If such a callback is not supported by the underlying runtime environment at all, the callback must be ignored and a corresponding warning should be logged.

Note that 'destruction' refers to to automatic destruction of the object as part of the scope's own lifecycle, not to the individual scoped object having been explicitly removed by the application. If a scoped object gets removed via this facade's Scope.remove(String) method, any registered destruction callback should be removed as well, assuming that the removed object will be reused or manually destroyed.

Specified by:

registerDestructionCallback in interface Scope

Parameters:

name - the name of the object to execute the destruction callback for

callback - the destruction callback to be executed. Note that the passed-in Runnable will never throw an exception, so it can safely be executed without an enclosing try-catch block. Furthermore, the Runnable will usually be serializable, provided that its target object is serializable as well.

See Also:

DisposableBean, AbstractBeanDefinition.getDestroyMethodName(), DestructionAwareBeanPostProcessor

resolveContextualObject

public Object resolveContextualObject(String key)

Description copied from interface: Scope

Resolve the contextual object for the given key, if any. E.g. the HttpServletRequest object for key "request".

Specified by:

resolveContextualObject in interface Scope

Parameters:

key - the contextual key

Returns:

the corresponding object, or null if none found

getConversationId

public String getConversationId()

Description copied from interface: Scope

Return the conversation ID for the current underlying scope, if any.

The exact meaning of the conversation ID depends on the underlying storage mechanism. In the case of session-scoped objects, the conversation ID would typically be equal to (or derived from) the session ID; in the case of a custom conversation that sits within the overall session, the specific ID for the current conversation would be appropriate.

Note: This is an optional operation. It is perfectly valid to return null in an implementation of this method if the underlying storage mechanism has no obvious candidate for such an ID.

Specified by:

getConversationId in interface Scope

Returns:

the conversation ID, or null if there is no conversation ID for the current scope

destroy

public void destroy()

Invoke all registered destruction callbacks. To be called on ServletContext shutdown.

Specified by:

destroy in interface DisposableBean

See Also:

ContextCleanupListener