AsyncHandlerMethodReturnValueHandler (Spring Framework 4.3.30.RELEASE API)

所有超级接口:
HandlerMethodReturnValueHandler
所有已知实现类:
AsyncTaskMethodReturnValueHandler, CallableMethodReturnValueHandler, CompletionStageReturnValueHandler, DeferredResultMethodReturnValueHandler, HandlerMethodReturnValueHandlerComposite, ListenableFutureReturnValueHandler, ResponseBodyEmitterReturnValueHandler
```
public interface AsyncHandlerMethodReturnValueHandler
extends HandlerMethodReturnValueHandler
```
A return value handler that supports async types. Such return value types need to be handled with priority so the async value can be "unwrapped".
Note: implementing this contract is not required but it should be implemented when the handler needs to be prioritized ahead of others. For example custom (async) handlers, by default ordered after built-in handlers, should take precedence over @ResponseBody or @ModelAttribute handling, which should occur once the async value is ready. By contrast, built-in (async) handlers are already ordered ahead of sync handlers.
从以下版本开始:
4.2
作者:
Rossen Stoyanchev

方法概要

所有方法实例方法抽象方法
修饰符和类型	方法	说明
`boolean`	`isAsyncReturnValue(Object returnValue, MethodParameter returnType)`	Whether the given return value represents asynchronous computation.

从接口继承的方法 org.springframework.web.method.support.HandlerMethodReturnValueHandler
handleReturnValue, supportsReturnType

- 方法详细资料
  - isAsyncReturnValue
```
boolean isAsyncReturnValue(Object returnValue,
                           MethodParameter returnType)
```
    Whether the given return value represents asynchronous computation.
    参数:
    returnValue - the value returned from the handler method
    returnType - the return type
    返回:
    true if the return value type represents an async value