Interface AsyncHandlerMethodReturnValueHandler

All Superinterfaces:

HandlerMethodReturnValueHandler

All Known Implementing Classes:

AbstractAsyncReturnValueHandler, CompletableFutureReturnValueHandler, HandlerMethodReturnValueHandlerComposite, ReactiveReturnValueHandler

public interface AsyncHandlerMethodReturnValueHandler
extends HandlerMethodReturnValueHandler

An extension of HandlerMethodReturnValueHandler for handling async, Future-like return value types that support success and error callbacks.

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, org.springframework.core.MethodParameter returnType)	Whether the return value represents an asynchronous, Future-like type with success and error callbacks.
@Nullable CompletableFuture<?>	toCompletableFuture(Object returnValue, org.springframework.core.MethodParameter returnType)	Adapt the asynchronous return value to a CompletableFuture.

Methods inherited from interface HandlerMethodReturnValueHandler

handleReturnValue, supportsReturnType

Method Details

isAsyncReturnValue

boolean isAsyncReturnValue(Object returnValue,
 org.springframework.core.MethodParameter returnType)

Whether the return value represents an asynchronous, Future-like type with success and error callbacks. If this method returns true, then toCompletableFuture(Object, MethodParameter) is invoked next. If it returns false, then HandlerMethodReturnValueHandler.handleReturnValue(Object, MethodParameter, 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

toCompletableFuture

@Nullable CompletableFuture<?> toCompletableFuture(Object returnValue,
 org.springframework.core.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