防止在会话托管bean中调用多个getter? [英] Preventing multiple getter invoke in a session managed bean?

问题描述

我正在使用jsf 2.0.2 + richfaces 3.3.3. 我该怎么办，这样我的吸气剂将不会被多次调用?

i'm using jsf 2.0.2 + richfaces 3.3.3. what can i do so my getter won't be invoked multiple time ??

我有这个:

@ManagedBean(name = "mybean")
@SessionScoped
public class mybean implements Serializable {        
public MyClass getMyClass() {
        if (FacesContext.getCurrentInstance().getRenderResponse()) {
            myClass = get_it_from_database();
        }
        return myClass;
    }

我也使用了这个:

@ManagedBean(name = "mybean")
@SessionScoped
public class mybean implements Serializable {        
public MyClass getMyClass() {
        if (myClass = null) {
            myClass = get_it_from_database();
        }
        return myClass;
    }

但是我想要的是每当刷新页面时就刷新"一次我的数据...

but what i wanted is to "refresh" ONCE my data whenever i refresh the page...

推荐答案

您无法阻止.那就是吸气剂的本质.一种getter方法旨在返回数据(阅读:为外部提供访问点)，而不是加载数据.在那里，您通常使用bean构造函数，@PostConstruct或action方法.

You can't prevent that. That's the nature of a getter. A getter method is intented to return data (read: to provide an access point for outside), not to load data. There you normally use the bean constructor, @PostConstruct or action method for.

要解决您的特定问题，请重新声明要请求范围的bean，并将行myClass = get_it_from_database();移动到bean的构造函数或@PostConstruct方法(如果它已注入依赖项).或者，如果您真的坚持让它保持会话范围(您应该更喜欢使用两个bean:一个会话范围为会话范围的数据，另一个请求范围为请求范围的数据)，那么您的第一种方法是最合理的.

To solve your particular problem, redeclare the bean to be request scoped and move the line myClass = get_it_from_database(); to bean's constructor or a @PostConstruct method if it has injected dependencies. Or if you really insist in keeping it session scoped (you should prefer having two beans: one session scoped for session scoped data and one request scoped for request scoped data), then your first approach is the most reasonable.

• 为什么JSF多次调用getter?

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