如何使用selectOneListBox和AJAX动态更改panelGroup

Question

我想根据所选项更改菜单的外观。

如何获得使用托管bean的selectonelistbox的值?

豆来源:

    public void selectOneMenuListener(ValueChangeEvent event) {
    Object newValue = (String) event.getNewValue(); 
    selectedMenu = newValue.toString();
}
public String getSelectedMenu() {
    return selectedMenu;
}
public void setSelectedMenu(String selectedMenu) {
    this.selectedMenu = selectedMenu;
}

页面:

    <h:panelGroup id="panel">
    <h:selectOneListbox id="katProduktu" valueChangeListener="#{produkt_KatBean.selectOneMenuListener}">
        <f:selectItems value="#{produkt_KatBean.produkt_KatAllList}"
            var="pk" itemLabel="#{pk.symbol}" itemValue="#{pk.id}"/>
        <f:ajax render="produktMenu" event="change" execute="@this" />
    </h:selectOneListbox>
</h:panelGroup>
<h:panelGroup layout="block" id="produktMenu">
    <h:panelGroup rendered="#{produkt_KatBean.selectedMenu==1}">
        Menu 1
    </h:panelGroup>
    <h:panelGroup rendered="#{produkt_KatBean.selectedMenu==2}">
        Menu 2
    </h:panelGroup>
    <h:panelGroup rendered="#{produkt_KatBean.selectedMenu==3}">
        Menu 3
    </h:panelGroup>     
    <h:panelGroup rendered="#{produkt_KatBean.selectedMenu==4}">
        Manu 4
    </h:panelGroup>
</h:panelGroup>

谢谢!

Answer 1

不要使用valueChangeListener。这个工具不适合这个工作。只需将该属性绑定到菜单组件的value属性，并让rendered属性拦截它。这样你根本不需要一个倾听者。你的rendered比较也不会对字符串起作用。您应该使用== '1'而不是== 1等，但这显然是笨拙的，只需将其改为Long(或Integer)。

<h:panelGroup id="panel">
    <h:selectOneListbox id="katProduktu" value="#{produkt_KatBean.selectedMenu}">
        <f:selectItems value="#{produkt_KatBean.produkt_KatAllList}"
            var="pk" itemLabel="#{pk.symbol}" itemValue="#{pk.id}"/>
        <f:ajax render="produktMenu" />
    </h:selectOneListbox>
</h:panelGroup>
<h:panelGroup layout="block" id="produktMenu">
    <h:panelGroup rendered="#{produkt_KatBean.selectedMenu==1}">
        Menu 1
    </h:panelGroup>
    <h:panelGroup rendered="#{produkt_KatBean.selectedMenu==2}">
        Menu 2
    </h:panelGroup>
    <h:panelGroup rendered="#{produkt_KatBean.selectedMenu==3}">
        Menu 3
    </h:panelGroup>     
    <h:panelGroup rendered="#{produkt_KatBean.selectedMenu==4}">
        Manu 4
    </h:panelGroup>
</h:panelGroup>

与

private Long selectedMenu; // Or Integer? Should be the same type as #{pk.id}.
// +getter +setter

(注意我省略了<f:ajax>的event和execute属性，因为它们已经代表了默认值)