Class DeferredResult<T>
- Type Parameters:
T
- the result type
DeferredResult
provides an alternative to using a Callable
for
asynchronous request processing. While a Callable
is executed concurrently
on behalf of the application, with a DeferredResult
the application can
produce the result from a thread of its choice.
Subclasses can extend this class to easily associate additional data or behavior
with the DeferredResult
. For example, one might want to associate the user
used to create the DeferredResult
by extending the class and adding an
additional property for the user. In this way, the user could easily be accessed
later without the need to use a data structure to do the mapping.
An example of associating additional behavior to this class might be realized
by extending the class to implement an additional interface. For example, one
might want to implement Comparable
so that when the DeferredResult
is added to a PriorityQueue
it is handled in the correct order.
- Since:
- 3.2
- Author:
- Rossen Stoyanchev, Juergen Hoeller, Rob Winch, Sam Brannen
-
Nested Class Summary
Modifier and TypeClassDescriptionstatic interface
Handles a DeferredResult value when set. -
Constructor Summary
ConstructorDescriptionCreate a DeferredResult.DeferredResult
(Long timeoutValue) Create a DeferredResult with a custom timeout value.DeferredResult
(Long timeoutValue, Object timeoutResult) Create a DeferredResult with a timeout value and a default result to use in case of timeout.DeferredResult
(Long timeoutValue, Supplier<?> timeoutResult) Variant ofDeferredResult(Long, Object)
that accepts a dynamic fallback value based on aSupplier
. -
Method Summary
Modifier and TypeMethodDescriptionReturn the result, ornull
if the result wasn't set.boolean
Returntrue
if the DeferredResult has been set.final boolean
Returntrue
if this DeferredResult is no longer usable either because it was previously set or because the underlying request expired.void
onCompletion
(Runnable callback) Register code to invoke when the async request completes.void
Register code to invoke when an error occurred during the async request.void
Register code to invoke when the async request times out.boolean
setErrorResult
(Object result) Set an error value for theDeferredResult
and handle it.boolean
Set the value for the DeferredResult and handle it.final void
setResultHandler
(DeferredResult.DeferredResultHandler resultHandler) Provide a handler to use to handle the result value.
-
Constructor Details
-
DeferredResult
public DeferredResult()Create a DeferredResult. -
DeferredResult
Create a DeferredResult with a custom timeout value.By default not set in which case the default configured in the MVC Java Config or the MVC namespace is used, or if that's not set, then the timeout depends on the default of the underlying server.
- Parameters:
timeoutValue
- timeout value in milliseconds
-
DeferredResult
Create a DeferredResult with a timeout value and a default result to use in case of timeout.- Parameters:
timeoutValue
- timeout value in milliseconds (ignored ifnull
)timeoutResult
- the result to use
-
DeferredResult
Variant ofDeferredResult(Long, Object)
that accepts a dynamic fallback value based on aSupplier
.- Parameters:
timeoutValue
- timeout value in milliseconds (ignored ifnull
)timeoutResult
- the result supplier to use- Since:
- 5.1.1
-
-
Method Details
-
isSetOrExpired
public final boolean isSetOrExpired()Returntrue
if this DeferredResult is no longer usable either because it was previously set or because the underlying request expired.The result may have been set with a call to
setResult(Object)
, orsetErrorResult(Object)
, or as a result of a timeout, if a timeout result was provided to the constructor. The request may also expire due to a timeout or network error. -
hasResult
public boolean hasResult()Returntrue
if the DeferredResult has been set.- Since:
- 4.0
-
getResult
Return the result, ornull
if the result wasn't set. Since the result can also benull
, it is recommended to usehasResult()
first to check if there is a result prior to calling this method.- Since:
- 4.0
-
onTimeout
Register code to invoke when the async request times out.This method is called from a container thread when an async request times out before the
DeferredResult
has been populated. It may invokesetResult
orsetErrorResult
to resume processing. -
onError
Register code to invoke when an error occurred during the async request.This method is called from a container thread when an error occurs while processing an async request before the
DeferredResult
has been populated. It may invokesetResult
orsetErrorResult
to resume processing.- Since:
- 5.0
-
onCompletion
Register code to invoke when the async request completes.This method is called from a container thread when an async request completed for any reason including timeout and network error. This is useful for detecting that a
DeferredResult
instance is no longer usable. -
setResultHandler
Provide a handler to use to handle the result value.- Parameters:
resultHandler
- the handler- See Also:
-
setResult
Set the value for the DeferredResult and handle it.- Parameters:
result
- the value to set- Returns:
true
if the result was set and passed on for handling;false
if the result was already set or the async request expired- See Also:
-
setErrorResult
Set an error value for theDeferredResult
and handle it. The value may be anException
orThrowable
in which case it will be processed as if a handler raised the exception.- Parameters:
result
- the error result value- Returns:
true
if the result was set to the error value and passed on for handling;false
if the result was already set or the async request expired- See Also:
-