org.springframework.web.context.request

Interface RequestAttributes

All Known Subinterfaces:

AsyncWebRequest, NativeWebRequest, WebRequest

All Known Implementing Classes:

AbstractRequestAttributes, DispatcherServletWebRequest, FacesRequestAttributes, FacesWebRequest, ServletRequestAttributes, ServletWebRequest, StandardServletAsyncWebRequest

public interface RequestAttributes

Abstraction for accessing attribute objects associated with a request. Supports access to request-scoped attributes as well as to session-scoped attributes, with the optional notion of a "global session".

Can be implemented for any kind of request/session mechanism, in particular for servlet requests.

Since:

2.0

Author:

Juergen Hoeller

See Also:

ServletRequestAttributes

Field Summary

Fields

Modifier and Type	Field and Description
static String	REFERENCE_REQUEST Name of the standard reference to the request object: "request".
static String	REFERENCE_SESSION Name of the standard reference to the session object: "session".
static int	SCOPE_REQUEST Constant that indicates request scope.
static int	SCOPE_SESSION Constant that indicates session scope.

Method Summary

Modifier and Type	Method and Description
Object	getAttribute(String name, int scope) Return the value for the scoped attribute of the given name, if any.
String[]	getAttributeNames(int scope) Retrieve the names of all attributes in the scope.
String	getSessionId() Return an id for the current underlying session.
Object	getSessionMutex() Expose the best available mutex for the underlying session: that is, an object to synchronize on for the underlying session.
void	registerDestructionCallback(String name, Runnable callback, int scope) Register a callback to be executed on destruction of the specified attribute in the given scope.
void	removeAttribute(String name, int scope) Remove the scoped attribute of the given name, if it exists.
Object	resolveReference(String key) Resolve the contextual reference for the given key, if any.
void	setAttribute(String name, Object value, int scope) Set the value for the scoped attribute of the given name, replacing an existing value (if any).

Field Detail

SCOPE_REQUEST

static final int SCOPE_REQUEST

Constant that indicates request scope.

See Also:

Constant Field Values

SCOPE_SESSION

static final int SCOPE_SESSION

Constant that indicates session scope.

This preferably refers to a locally isolated session, if such a distinction is available (for example, in a Portlet environment). Else, it simply refers to the common session.

See Also:

Constant Field Values

REFERENCE_REQUEST

static final String REFERENCE_REQUEST

Name of the standard reference to the request object: "request".

See Also:

resolveReference(java.lang.String), Constant Field Values

REFERENCE_SESSION

static final String REFERENCE_SESSION

Name of the standard reference to the session object: "session".

See Also:

resolveReference(java.lang.String), Constant Field Values

Method Detail

getAttribute

@Nullable
Object getAttribute(String name,
                              int scope)

Return the value for the scoped attribute of the given name, if any.

Parameters:

name - the name of the attribute

scope - the scope identifier

Returns:

the current attribute value, or null if not found

setAttribute

void setAttribute(String name,
                  Object value,
                  int scope)

Set the value for the scoped attribute of the given name, replacing an existing value (if any).

Parameters:

name - the name of the attribute

scope - the scope identifier

value - the value for the attribute

removeAttribute

void removeAttribute(String name,
                     int scope)

Remove the scoped attribute of the given name, if it exists.

Note that an implementation should also remove a registered destruction callback for the specified attribute, 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).

Parameters:

name - the name of the attribute

scope - the scope identifier

getAttributeNames

String[] getAttributeNames(int scope)

Retrieve the names of all attributes in the scope.

Parameters:

scope - the scope identifier

Returns:

the attribute names as String array

registerDestructionCallback

void registerDestructionCallback(String name,
                                 Runnable callback,
                                 int scope)

Register a callback to be executed on destruction of the specified attribute in the given scope.

Implementations should do their best to execute the callback at the appropriate time: that is, at request completion or session termination, respectively. If such a callback is not supported by the underlying runtime environment, the callback must be ignored and a corresponding warning should be logged.

Note that 'destruction' usually corresponds to destruction of the entire scope, not to the individual attribute having been explicitly removed by the application. If an attribute gets removed via this facade's removeAttribute(String, int) method, any registered destruction callback should be disabled as well, assuming that the removed object will be reused or manually destroyed.

NOTE: Callback objects should generally be serializable if they are being registered for a session scope. Otherwise the callback (or even the entire session) might not survive web app restarts.

Parameters:

name - the name of the attribute to register the callback for

callback - the destruction callback to be executed

scope - the scope identifier

resolveReference

@Nullable
Object resolveReference(String key)

Resolve the contextual reference for the given key, if any.

At a minimum: the HttpServletRequest/PortletRequest reference for key "request", and the HttpSession/PortletSession reference for key "session".

Parameters:

key - the contextual key

Returns:

the corresponding object, or null if none found

getSessionId

String getSessionId()

Return an id for the current underlying session.

Returns:

the session id as String (never null)

getSessionMutex

Object getSessionMutex()

Expose the best available mutex for the underlying session: that is, an object to synchronize on for the underlying session.

Returns:

the session mutex to use (never null)