将托管 bean 实例绑定到复合组件 [英] Binding a managed bean instance to composite component

问题描述

我有一个复合组件(collapsiblePanel).该组件使用可折叠"bean 来提供切换功能.当我在一个页面上多次使用同一个组件时，该组件的每个实例都绑定到同一个 bean 实例.如何实现类似组件作用域 bean 的功能?

I have a composite component (collapsiblePanel). The component uses the "collapsible" bean to provide the toggle function. When I use the same component multiple times on a page, each instance of the component is bound to the same bean instance. How Can I achieve something like a component scoped bean?

collapsibleTemp.xhtml:

<cc:interface>
    <cc:attribute name="model" required="true">
        <cc:attribute name="collapsed" required="true" />
        <cc:attribute name="toggle" required="true"
            method-signature="java.lang.String f()" />
    </cc:attribute>
    <cc:actionSource name="toggle" />
    <cc:facet name="header" />
    <cc:facet name="body" />
</cc:interface>
<cc:implementation>
    <h:panelGroup layout="block" styleClass="collapsiblePanel-header">
        <h:commandButton id="toggle" action="#{cc.attrs.model.toggle}"
            styleClass="collapsiblePanel-img"
            image="#{cc.attrs.model.collapsed ? '/resources/images/plus.png' : '/resources/images/minus.png'}" />
        <cc:renderFacet name="header" />
    </h:panelGroup>
    <h:panelGroup layout="block" rendered="#{!cc.attrs.model.collapsed}">
        <cc:insertChildren />
        <cc:renderFacet name="body"></cc:renderFacet>
    </h:panelGroup>
    <h:outputStylesheet library="css" name="components.css" />
</cc:implementation>

支持bean:

@ManagedBean
@ViewScoped
public class Collapsible {

    private boolean collapsed = false;

    public boolean isCollapsed() {
        return collapsed;
    }

    public void setCollapsed(boolean collapsed) {
        this.collapsed = collapsed;
    }

    public String toggle() {
        collapsed = !collapsed;
        return null;
    }

}

使用页面

<h:form id="someid">
    <jl:collapsibletemp id="collapsiblePanel1" model="#{collapsible}">
        <f:facet name="header">
            <h3>
                <h:outputText value="Collapsible information" />
            </h3>
        </f:facet>
        <f:facet name="body">
            <h:outputText value="do something....." />
        </f:facet>
        <p />
    </jl:collapsibletemp>

    <jl:collapsibletemp id="collapsiblePanel2" model="#{collapsible}">
        <f:facet name="header">
            <h3>
                <h:outputText value="Collapsible information" />
            </h3>
        </f:facet>
        <f:facet name="body">
            <h:outputText value="do some tabbing" />
        </f:facet>
        <p />
    </jl:collapsibletemp>

    <jl:collapsibletemp id="collapsiblePanel3" model="#{collapsible}">
        <f:facet name="header">
            <h3>
                <h:outputText value="Collapsible information" />
            </h3>
        </f:facet>
        <f:facet name="body">
            <h:outputText value="notice board" />
        </f:facet>
        <p />
    </jl:collapsibletemp>
</h:form>

推荐答案

你可以使用 的 componentType 属性来定义一个backing组件".

You can use the componentType attribute of the <cc:interface> to define a "backing component".

例如

<cc:interface componentType="collapsiblePanel">
    ...
</cc:interface>
<cc:implementation>
    ...
    <h:commandButton action="#{cc.toggle}" ... />
    ...
    <h:panelGroup rendered="#{!cc.collapsed}" ...>
    ...
</cc:implementation>

只有一个 com.example.components.CollapsiblePanel

@FacesComponent(value="collapsiblePanel") // To be specified in componentType attribute.
public class CollapsiblePanel extends UINamingContainer { // Important! Must extend UINamingContainer.

    private boolean collapsed;

    public void toggle() {
        collapsed = !collapsed;
    }

    public boolean isCollapsed() {
        collapsed;
    }

}

然而，当您想要拥有多个这些组件时，您应该在视图中声明物理分离它们的实例.如果这需要动态发生，那么您需要使用 来生成它们的物理分离实例，而不是 使用单个零件.否则，您必须通过 Map 中的客户端 ID 映射所有 collapsed 状态.有关示例和更多背景信息，请参见 Getting每次使用时复合组件中`componentType`的相同实例

However, when you want to have multiple of those components, then you should declare physically separate instances of them in the view. If this needs to happen dynamically, then you need to use <c:forEach> to generate physically separate instances of them instead of <ui:repeat> with a single component. Otherwise you have to map all collapsed states by the client ID inside a Map<String, Boolean>. See for an example and more background information also Getting same instance of `componentType` in composite component on every use

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