Callable<>如果你想
spring.mvc.async.request-timeout=5000工作，则需要返回a 。
@RequestMapping(method = RequestMethod.GET)public Callable<String> getFoobar() throws InterruptedException { return new Callable<String>() { @Override public String call() throws Exception { Thread.sleep(8000); //this will cause a timeout return "foobar"; } };}
