jsf - 设置 selectonemenu 的默认值

Question

我有一个像这样的选择菜单:

<h:selectOneMenu value="#{serverMB.selectedServerType}"  >
    <f:converter binding="#{serverTypeConverter}"/>
    <f:selectItems value="#{serverMB.serverTypesList}" var="servertypes"
            itemLabel="#{servertypes.server_type_name}" />
    <f:ajax listener="#{serverMB.changeSelectedOneMenuServerType}" render="selectservertype"/>
</h:selectOneMenu>

我希望选择菜单的默认值是之前填充的一个对象的值，如下所示:

<h:selectOneMenu value="#{serverMB.selectedServerType}" default="serverMB.server.servertype">   // <- default

或者像这样:

<h:selectOneMenu value="#{serverMB.selectedServerType}">
    <f:converter binding="#{serverTypeConverter}"/>
    <f:selectItem value"serverMB.server.servertype"/> <-   but this item was the first one and has been selected  
    <f:selectItems value="#{serverMB.serverTypesList}" var="servertypes"
            itemLabel="#{servertypes.server_type_name}" />
</h:selectOneMenu>

Answer 1

如果调用页面时对象已经填充，则可以执行类似的操作，如果没有填充，则会显示 <f:selectItem/>消息:

<h:selectOneMenu value="#{serverMB.server.servertype}">
    <f:converter binding="#{serverTypeConverter}"/>
    <f:selectItem itemLabel="Select a Server..." />
    <f:selectItems value="#{serverMB.serverTypesList}" var="servertypes"
            itemLabel="#{servertypes.server_type_name}"/>
    <f:ajax listener="#{serverMB.changeSelectedOneMenuServerType}" 
            render="selectservertype"/>
</h:selectOneMenu>