org.springframework.messaging.handler.invocation

Interface AsyncHandlerMethodReturnValueHandler

All Superinterfaces:

HandlerMethodReturnValueHandler

All Known Implementing Classes:

AbstractAsyncReturnValueHandler, CompletableFutureReturnValueHandler, HandlerMethodReturnValueHandlerComposite, ListenableFutureReturnValueHandler

public interface AsyncHandlerMethodReturnValueHandler
extends HandlerMethodReturnValueHandler

An extension of HandlerMethodReturnValueHandler for handling async, Future-like return value types that support success and error callbacks. Essentially anything that can be adapted to a ListenableFuture.

Implementations should consider extending the convenient base class AbstractAsyncReturnValueHandler.

Since:

4.2

Author:

Rossen Stoyanchev

See Also:

AbstractAsyncReturnValueHandler

Method Summary

Modifier and Type	Method and Description
boolean	isAsyncReturnValue(java.lang.Object returnValue, MethodParameter returnType) Whether the return value represents an asynchronous, Future-like type with success and error callbacks.
ListenableFuture<?>	toListenableFuture(java.lang.Object returnValue, MethodParameter returnType) Adapt the asynchronous return value to a ListenableFuture.

Methods inherited from interface org.springframework.messaging.handler.invocation.HandlerMethodReturnValueHandler

handleReturnValue, supportsReturnType

Method Detail

isAsyncReturnValue

boolean isAsyncReturnValue(java.lang.Object returnValue,
                           MethodParameter returnType)

Whether the return value represents an asynchronous, Future-like type with success and error callbacks. If this method returns true, then toListenableFuture(java.lang.Object, org.springframework.core.MethodParameter) is invoked next. If it returns false, then HandlerMethodReturnValueHandler.handleReturnValue(java.lang.Object, org.springframework.core.MethodParameter, org.springframework.messaging.Message<?>) is called.

Note: this method will only be invoked after HandlerMethodReturnValueHandler.supportsReturnType(org.springframework.core.MethodParameter) is called and it returns true.

Parameters:

returnValue - the value returned from the handler method

returnType - the type of the return value.

Returns:

true if the return value type represents an async value.

toListenableFuture

ListenableFuture<?> toListenableFuture(java.lang.Object returnValue,
                                       MethodParameter returnType)

Adapt the asynchronous return value to a ListenableFuture. Implementations should consider returning an instance of SettableListenableFuture. Return value handling will then continue when the ListenableFuture is completed with either success or error.

Note: this method will only be invoked after HandlerMethodReturnValueHandler.supportsReturnType(org.springframework.core.MethodParameter) is called and it returns true.

Parameters:

returnValue - the value returned from the handler method

returnType - the type of the return value.

Returns:

the resulting ListenableFuture or null in which case no further handling will be performed.