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- @ViewScoped calls @PostConstruct on every postback request 1 answer
- @ViewScoped对每个回发请求1的回答调用@PostConstruct
I have a @ViewScope ManagedBean and a @PostConstruct initialisation method. This method is called when a new instance is created, but also on every ajax call. Why is this so?
我有一个@ViewScope ManagedBean和一个@PostConstruct初始化方法。在创建新实例时调用此方法，在每次ajax调用时也调用此方法。为什么会这样呢?
On an AJAX-call the init-Method is called and executed, but no changes are visible. For example if I change a property in the init-Method, this is only visible on instatiation and not for AJAX-calls. For AJAX-calls the value change is not persistent in the @ViewScoped Bean.
在ajax调用中，将调用并执行init方法，但不可见任何更改。例如，如果我在init方法中更改一个属性，这只在instatiation中可见，而不是在ajax调用中可见。对于ajax调用，值更改在@ViewScoped Bean中不是持久的。
Can anyone tell why this is so? How can I change this?
有人知道为什么会这样吗?我如何改变这个?
1 个解决方案
#1
11
This is not normal behavior. This will happen if you bind tag handler attributes or the binding attribute of JSF components to a property of a view scoped bean while partial state saving is turned on. This is known as issue 1492 which is fixed in (the upcoming) Mojarra 2.2.
这不是正常的行为。当打开部分状态保存时，如果将标记处理程序属性或JSF组件的绑定属性绑定到视图作用域bean的属性，就会发生这种情况。这被称为第1492期，将在(即将到来的)Mojarra 2.2中解决。
In general, you can recognize tag handlers by the lack of the rendered attribute. E.g. <c:if>, <f:validator>, <ui:include>, etc. If you bind an attribute of such a tag handler to a property of the view scoped bean like follows
通常，您可以通过缺少呈现的属性来识别标记处理程序。例:
<c:if test="#{viewScopedBean.something}"></c:if>
<h:inputText><f:validator binding="#{viewScopedBean.validate}" /></h:inputText>
<ui:include src="#{viewScopedBean.includePage}" />
then the view scoped bean will be recreated everytime the view is to be restored from a partially saved state. This is a chicken-egg issue with the view scope, because in order to get the right view scoped bean, it has to be extracted from the restored view.
然后，每次视图从部分保存的状态中恢复时，都会重新创建视图作用域bean。这是视图范围内的鸡-蛋问题，因为为了获得正确的视图范围bean，必须从恢复的视图中提取它。
This will also happen if you reference a property of a view scoped bean in the binding attribute of a JSF component.
如果在JSF组件的绑定属性中引用视图作用域bean的属性，也会发生这种情况。
<h:someComponent binding="#{viewScopedBean.someComponent}" />
See also:
- Communication in JSF 2.0 -
@ViewScopedfails in tag handlers - 在JSF 2.0 - @ViewScoped中的通信在标记处理程序中失败。
#1
11
This is not normal behavior. This will happen if you bind tag handler attributes or the binding attribute of JSF components to a property of a view scoped bean while partial state saving is turned on. This is known as issue 1492 which is fixed in (the upcoming) Mojarra 2.2.
这不是正常的行为。当打开部分状态保存时，如果将标记处理程序属性或JSF组件的绑定属性绑定到视图作用域bean的属性，就会发生这种情况。这被称为第1492期，将在(即将到来的)Mojarra 2.2中解决。
In general, you can recognize tag handlers by the lack of the rendered attribute. E.g. <c:if>, <f:validator>, <ui:include>, etc. If you bind an attribute of such a tag handler to a property of the view scoped bean like follows
通常，您可以通过缺少呈现的属性来识别标记处理程序。例:
<c:if test="#{viewScopedBean.something}"></c:if>
<h:inputText><f:validator binding="#{viewScopedBean.validate}" /></h:inputText>
<ui:include src="#{viewScopedBean.includePage}" />
then the view scoped bean will be recreated everytime the view is to be restored from a partially saved state. This is a chicken-egg issue with the view scope, because in order to get the right view scoped bean, it has to be extracted from the restored view.
然后，每次视图从部分保存的状态中恢复时，都会重新创建视图作用域bean。这是视图范围内的鸡-蛋问题，因为为了获得正确的视图范围bean，必须从恢复的视图中提取它。
This will also happen if you reference a property of a view scoped bean in the binding attribute of a JSF component.
如果在JSF组件的绑定属性中引用视图作用域bean的属性，也会发生这种情况。
<h:someComponent binding="#{viewScopedBean.someComponent}" />
See also:
- Communication in JSF 2.0 -
@ViewScopedfails in tag handlers - 在JSF 2.0 - @ViewScoped中的通信在标记处理程序中失败。