如何在加载JSF页面之前在后备bean中启动特殊的init事件? [英] How to start special init event in a backing bean before JSF page loads?

问题描述

PF 3.5.10，Mojarra 2.1.21，Omnifaces 1.5

PF 3.5.10, Mojarra 2.1.21, Omnifaces 1.5

在加载.xhtml JSF页面之前，如何调用某些(CDI)SessionScoped bean的特殊init()方法?现在，如果用户从站点菜单中选择页面(使用p:menutitem)，我将调用init().但是，如果用户使用浏览器地址行直接输入url怎么办?

How to call special init()-method of some (CDI)SessionScoped bean before I load a .xhtml JSF page ? Now I call init() if user select the page from site menu (with p:menutitem). But what to do if the user use browser address line to type url directly?

my.xhtml:

<ui:define template="/mytemp.xhtml">
   <f:event type="preRenderView" listener="#{mybean.init()}" />
   <h:form>
     <p:commandButton update="@form" ... />
   </h:form>
</ui:define>

如果我这样做的话，在每次更新时(即在每次回发到服务器时)都会调用init()，例如在每次单击CommandButton时都会调用init().所以我不能使用你的建议.

If I do it that way the init() will be called on every update (i.e. on every postback to a server),in example on every click of commandButton. So I can not use your proposal.

谢谢Luiggi Mendoza和BalusC！ 除了来自Luiggi Mendoza的解决方案外，如评论中所述，Omnifaces 1.6也将具有ViewScope.

Edit 2: Thank you Luiggi Mendoza, and BalusC! In addtion to solution from Luiggi Mendoza, as in comments stated the Omnifaces 1.6 will be have ViewScope also.

推荐答案

问题是在创建托管bean和注入字段之后调用@PostConstruct public void init()方法.由于您的bean是@SessionScoped，它将一直存在直到用户会话过期为止.

The problem is that the @PostConstruct public void init() method is called after the managed bean is created and the fields are injected. Since your bean is @SessionScoped, it will live until the user session expires.

一种解决方法是按照以下说明使用<f:event type="preRenderView" listener="{bean.init}" />:什么可以< f:metadata> ;,< f: viewParam>和< f:viewAction> 用于?(不需要使用BalusC在此处解释的<f:metadata>:是否放置f:event是否重要是否在f:metadata内部?).

A way to solve is to use <f:event type="preRenderView" listener="{bean.init}" /> as explained here: What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for? (no need to use <f:metadata> as explained by BalusC here: Does it matter whether place f:event inside f:metadata or not?).

根据您的问题更新，此问题将在第一个链接中处理.我将发布相关代码来处理这种情况(摘自BalusC答案):

Per your question update, this problem is handled in the first link. I'll post the relevant code to handle this situation (taken from BalusC answer):

public void init() {
    FacesContext facesContext = FacesContext.getCurrentInstance();
    if (!facesContext.isPostback() && !facesContext.isValidationFailed()) {
        // ...
    }
}

如果您迁移到JSF 2.2，则有一个CDI bean的@ViewScoped注释，您可以相应地缩小@SessionScoped bean的范围.

If you migrate to JSF 2.2, then there's a @ViewScoped annotation for CDI beans and you could reduce the scope of your @SessionScoped beans accordingly.

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