如何与h:commandButton一起传递参数

Question

在JSF + Seam中更改语言环境的最常用方法之一 - 使用<h:selectOneMenu>:

<h:form  action="#{localeSelector.select}" rendered="false">
    <h:selectOneMenu value="#{localeSelector.language}" onchange="submit()">
        <f:selectItem itemLabel="English" itemValue="en" />
        <f:selectItem itemLabel="Francais" itemValue="fr" />
    </h:selectOneMenu>
</h:form>

我想用按钮实现区域设置更改.所以,问题是 - 如何传递参数(en,fr等)来更新bean <h:commandButton>？也许<h:inputHidden>会有所帮助？

Answer 1

要么作为方法参数传递(仅当您的环境支持EL 2.2时),

<h:commandButton value="English" action="#{localeSelector.change('en')}" />
<h:commandButton value="Deutsch" action="#{localeSelector.change('de')}" />
<h:commandButton value="Français" action="#{localeSelector.change('fr')}" />

同

public void change(String language) {
    locale = new Locale(language);
    // ...
}

或者使用 <f:setPropertyActionListener>

<h:commandButton value="English" action="#{localeSelector.change}">
    <f:setPropertyActionListener target="#{localeSelector.language}" value="en" />
</h:commandButton>
<h:commandButton value="Deutsch" action="#{localeSelector.change}">
    <f:setPropertyActionListener target="#{localeSelector.language}" value="de" />
</h:commandButton>
<h:commandButton value="Français" action="#{localeSelector.change}">
    <f:setPropertyActionListener target="#{localeSelector.language}" value="fr" />
</h:commandButton>

同

private String language;

public void change() {
    locale = new Locale(language);
    // ...
}

或者使用 <f:param>

<h:commandButton value="English" action="#{localeSelector.change}">
    <f:param name="language" value="en" />
</h:commandButton>
<h:commandButton value="Deutsch" action="#{localeSelector.change}">
    <f:param name="language" value="de" />
</h:commandButton>
<h:commandButton value="Français" action="#{localeSelector.change}">
    <f:param name="language" value="fr" />
</h:commandButton>

同

public void change() {
    locale = new Locale(FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("language"));
    // ...
}

(你也可以让JSF自动设置它@ManagedProperty("#{param.language}"),但是这需要bean作为请求作用域,或者a <f:viewParam>,另见ViewParam vs @ManagedProperty(value ="#{param.id}"))

有足够的方法将参数从视图传递到控制器.随便挑选.的<h:inputHidden>在JSF上下文供应稍微不同的目的,它只能由JavaScript在操纵onclick这是难看.