SpringMVC异步处理 可使用的返回值类型

CallableMethodReturnValueHandler
    Callable.class.isAssignableFrom(returnType.getParameterType());


DeferredResultMethodReturnValueHandler
    (DeferredResult.class.isAssignableFrom(type) ||
        ListenableFuture.class.isAssignableFrom(type) ||
        CompletionStage.class.isAssignableFrom(type));


AsyncTaskMethodReturnValueHandler
    WebAsyncTask.class.isAssignableFrom(returnType.getParameterType());