Package org.springframework.messaging.handler.invocation

Interface AsyncHandlerMethodReturnValueHandler

All Superinterfaces:

HandlerMethodReturnValueHandler

All Known Implementing Classes:

AbstractAsyncReturnValueHandler, CompletableFutureReturnValueHandler, HandlerMethodReturnValueHandlerComposite, ListenableFutureReturnValueHandler, ReactiveReturnValueHandler

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	Description
boolean	isAsyncReturnValue(Object returnValue, MethodParameter returnType)	Whether the return value represents an asynchronous, Future-like type with success and error callbacks.
CompletableFuture<?>	toCompletableFuture(Object returnValue, MethodParameter returnType)	Adapt the asynchronous return value to a CompletableFuture.
default ListenableFuture<?>	toListenableFuture(Object returnValue, MethodParameter returnType)	Deprecated. as of 6.0, in favor of toCompletableFuture(Object, MethodParameter)

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

handleReturnValue, supportsReturnType

Method Details

isAsyncReturnValue

boolean isAsyncReturnValue(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 toCompletableFuture(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

@Deprecated(since="6.0")
@Nullable
default ListenableFuture<?> toListenableFuture(Object returnValue,
 MethodParameter returnType)

Deprecated.

as of 6.0, in favor of toCompletableFuture(Object, MethodParameter)

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

toCompletableFuture

@Nullable
CompletableFuture<?> toCompletableFuture(Object returnValue,
 MethodParameter returnType)

Adapt the asynchronous return value to a CompletableFuture.

Return value handling will then continue when the CompletableFuture 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 CompletableFuture, or null in which case no further handling will be performed

Since:

6.0