`@SessionAttribute`

如果你需要访问全局管理的预先存在的会话属性（即控制器外部，例如，由过滤器管理），并且该属性可以存在也可以不存在，那么可以在方法参数上使用 @SessionAttribute 注解，如下例所示：

If you need access to pre-existing session attributes that are managed globally (that is, outside the controller — for example, by a filter) and may or may not be present, you can use the @SessionAttribute annotation on a method parameter, as the following example shows:

Java
Kotlin

@GetMapping("/")
public String handle(@SessionAttribute User user) { (1)
	// ...
}

1	Using `@SessionAttribute`.

@GetMapping("/")
fun handle(@SessionAttribute user: User): String { (1)
	// ...
}

1	Using `@SessionAttribute`.

对于需要添加或删除会话属性的用例，请考虑将 WebSession 注入到控制器方法。

For use cases that require adding or removing session attributes, consider injecting WebSession into the controller method.

对于在控制器工作流中作为会话的一部分临时存储模型属性，请考虑使用 SessionAttributes，如 @SessionAttributes 中所述。

For temporary storage of model attributes in the session as part of a controller workflow, consider using SessionAttributes, as described in @SessionAttributes.