我可以在同一个xhtml页面中使用多个托管bean吗? [英] Can I use multiple managed bean in the same xhtml page?

问题描述

当数据在几页中重复时(参考示例) 是我可以加载到单个托管bean中，并且在同一页面中使用多个托管bean. 有什么影响?

解决方案

我可以在同一个xhtml页面中使用多个托管bean吗?

是的，您可以，我强烈建议您尝试一下:).

有什么影响?

这取决于托管bean的作用域.一个很好的例子是查看一个新地址的视图，并在页面顶部显示已记录的用户信息，类似于您在其中添加新送货地址的Amazon网站.

在这种情况下，您可以在三个托管Bean中拥有一个:

• 一个@SessionScoped bean，它将显示已记录的用户信息.如果是亚马逊视图，则仅显示名字.
• 一个@ApplicationScoped bean，它将提供国家/地区的数据.该信息不会经常更改(至少每天都有一个新国家出生==).
• 一个@ViewScoped bean，它将处理请求数据，错误消息和注册.

Facelets代码中上述解释的示例:

 <div id="top">
    Hello #{sessionBean.user.firstName}
</div>
<div id="body">
    <h1>Add an address</h1>
    <h:form id="frmAddress">
        <h:panelGrid columns="2">
            <h:outputText value="Address" />
            <h:inputText id="txtAddress" value="#{viewBean.address}" />
            <h:outputText value="Country" />
            <h:selectOneMenu id="ddlCountry" value="#{viewBean.selectedCountry}">
                <f:selectItems value="#{applicationBean.countries}" var="country"
                    itemLabel="#{country.name}" itemValue="#{country}" />
            </h:selectOneMenu>
        </h:panelGrid>
        <h:messages id="msgErrors" />
        <h:commandButton value="Save address" action="#{viewBean.saveAddress}" />
    </h:form>
</div>
 

注意:这既不是好事也不是坏事，只需尝试一下它的行为即可.影响的定义是页面中每个托管bean的行为，因此根据您定义bean的方式，它会非常整洁或非常糟糕.

相关信息:

• 为什么JSF多次调用getters
• JSF 2中的通信:托管bean范围

when there are data that are repeated in several pages (reference example) Is that I can load into a single managed bean and I use several managed bean in the same page. What is its impact?

解决方案

Can I use multiple managed bean in the same xhtml page?

Yes, you can, I highly recommend you to try it :).

What is its impact?

This depends on the managed beans scopes. A good example is having a view to register a new address and shows the logged user info at the top of the page, similar to Amazon site where you add a new shipping address.

In this case, you can have among three managed beans:

• A @SessionScoped bean that will show the logged user info. In case of amazon view, it shows only the first name.
• A @ApplicationScoped bean that will provide the data for Countries. This info doesn't change too often (at least that a new country is born every day =\).
• A @ViewScoped bean that will handle the request data, error messages and the registration.

A sample of the above explanation in Facelets code:

<div id="top">
    Hello #{sessionBean.user.firstName}
</div>
<div id="body">
    <h1>Add an address</h1>
    <h:form id="frmAddress">
        <h:panelGrid columns="2">
            <h:outputText value="Address" />
            <h:inputText id="txtAddress" value="#{viewBean.address}" />
            <h:outputText value="Country" />
            <h:selectOneMenu id="ddlCountry" value="#{viewBean.selectedCountry}">
                <f:selectItems value="#{applicationBean.countries}" var="country"
                    itemLabel="#{country.name}" itemValue="#{country}" />
            </h:selectOneMenu>
        </h:panelGrid>
        <h:messages id="msgErrors" />
        <h:commandButton value="Save address" action="#{viewBean.saveAddress}" />
    </h:form>
</div>

Note: this is nor a good nor a bad practice, just give it a try to see how this behaves. The impact is defined how each managed bean behaves in the page, so it will be pretty neat or a really bad experience, based on how you have defined the beans.

Related info:

• Why JSF calls getters multiple times
• Communication in JSF 2: Managed bean scopes

这篇关于我可以在同一个xhtml页面中使用多个托管bean吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！