[英]Get fields of generic type object in Java
I have a class called "Person": 我有一堂课叫做“人”:
public Class Person {
String name;
String address;
}
A public method is used to return a Person object by using RestTemplate as below. 公共方法用于通过使用RestTemplate来返回Person对象,如下所示。 My question is that how I print the name and the address of the Person object if I use generic type T for Person?
我的问题是,如果我对Person使用通用类型T,如何打印Person对象的名称和地址? I know I can do "instanceOf", but if "log" needs to handle many different types, then I will have to do "instanceOf" for each of them.
我知道我可以执行“ instanceOf”,但是如果“ log”需要处理许多不同的类型,那么我将必须为每个类型执行“ instanceOf”。 Anyone has a better approach?
有人有更好的方法吗? Thanks.
谢谢。
public Person getPerson(SomeObject request) throws Exception {
String url =......;
return post(url, request, Pereson.class);
}
// This method can be used by response types other than Person
private <T> T post(String url,
Object request,
Class<T> responseType) throws Exception {
T response =
restTemplate.postForObject(url, request, responseType);
log(response, responseType);
return response;
}
private <T> void log(T response,
Class<T> responseType) throws Exception {
// how do I print the name and the address of the
// Person response object here?
}
The easiest thing to do in this context is to delegate to the instance. 在这种情况下,最简单的事情就是委托给实例。 Since you have no way to determine what that instance will be - it may be anything, really - the most effective way to log out critical information about the response would be to just invoke
toString
on response
. 既然你没有办法确定这个实例将是什么 -它可以是任何东西,真的-注销有关工作的关键信息的最有效的方法是只调用
toString
的response
。
This means you need a suitable toString
method attached to Person
, which displays the name and address. 这意味着您需要一个附加到
Person
的合适的toString
方法,该方法显示名称和地址。
Anything else - dealing with instanceof
or any kind of dodgy casting - is too risky and brittle when you need to introduce new classes which have to be logged. 当您需要引入必须记录的新类时, 其他任何事情 -处理
instanceof
或任何类型的躲猫猫-都太冒险和脆弱。
There are a couple reasonable approached. 有一些合理的方法。
Person
implement a Printable
interface and declare T extends Person
. Person
实现一个Printable
接口并声明T extends Person
。 (Using Object::toString
makes this simpler, but may be the wrong thing to do.) Object::toString
可以简化此过程,但是这样做可能是错误的。) Printer
(or even Printer<T>
), to stand in for Person
. Printer
(甚至是Printer<T>
)来代替Person
。 Write a set of overloaded static (or not) functions to wrap the likes of Person
into Printer
s (or even write inline as a lambda). Person
包装到Printer
(甚至内联为lambda编写)。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.