在值插入时计算值

Question

我想创建非常简单的JSF网页，我想用它来计算价格：

<h:form>
    <h:outputText value="Number of Computers"/>
    <h:panelGroup layout="block" id="desktopClients_select" style="padding-top: 3px;" styleClass="text">
        <h:inputText id="desktopClients" value="#{pricingCalculator.computers}">
            <f:ajax event="change" render="@form" listener="#{pricingCalculator.calculateTotalPrice}"/>
        </h:inputText>
    </h:panelGroup>
    <h:outputText value="Email support incidents"/>
    <h:panelGroup layout="block" id="email_support_incidents" style="padding-top: 3px;" styleClass="text">
        <h:inputText id="email_support_incidents_text" value="#{pricingCalculator.emailSupportIncidents}">
            <f:ajax event="change" render="@form" listener="#{pricingCalculator.calculateTotalPrice}"/>
        </h:inputText>
    </h:panelGroup>
    <h:outputText value="Phone support incidents"/>
    <h:panelGroup layout="block" id="phone_support_incidents" style="padding-top: 3px;" styleClass="text">
        <h:inputText id="phone_support_incidents_text" value="#{pricingCalculator.phoneSupportIncidents}">
            <f:validateLongRange minimum="1" maximum="150" />
            <f:ajax event="change" render="@form" listener="#{pricingCalculator.calculateTotalPrice}"/>
        </h:inputText>
    </h:panelGroup>
    <h:outputText value="Total price"/>
    <h:panelGroup layout="block" id="total_price" style="padding-top: 3px;" styleClass="text">
        <h:outputText value="#{pricingCalculator.calculateTotalPrice}"/>
    </h:panelGroup>
    </h:panelGrid>
</h:form>

豆：

@Named
@ViewScoped
public class PricingCalculator implements Serializable
{
    private int computers;
    private float emailSupportIncidents;
    private float phoneSupportIncidents;
    private float totalPrice;
    // Prices for each component and service    
    private final float computers_price = 299;
    private final float emailSupportIncidents_price = 300;
    private final float phoneSupportIncidents_price = 150;
    public String getCalculateTotalPrice()
    {
        totalPrice = (computers_price * computers)
            + (emailSupportIncidents_price * emailSupportIncidents)
            + (phoneSupportIncidents_price * phoneSupportIncidents);
        String result = Float.toString(totalPrice);
        return result;
    }
    public int getComputers()
    {
        return computers;
    }
    public void setComputers(int computers)
    {
        this.computers = computers;
    }
    public float getEmailSupportIncidents()
    {
        return emailSupportIncidents;
    }
    public void setEmailSupportIncidents(float emailSupportIncidents)
    {
        this.emailSupportIncidents = emailSupportIncidents;
    }
    public float getPhoneSupportIncidents()
    {
        return phoneSupportIncidents;
    }
    public void setPhoneSupportIncidents(float phoneSupportIncidents)
    {
        this.phoneSupportIncidents = phoneSupportIncidents;
    }
    public float getTotalPrice()
    {
        return totalPrice;
    }
    public void setTotalPrice(float totalPrice)
    {
        this.totalPrice = totalPrice;
    }
}

当我在输入字段中插入一些值时，我想重新计算总价。我现在有两个问题：我得到异常serverError: class javax.el.MethodNotFoundException /pricing_calculator.xhtml @115,136 listener="#{pricingCalculator.calculateTotalPrice}": Method not found: [e-mail](javax.faces.event.AjaxBehaviorEvent)

当我插入新值时，前一个设置为零。记不清了。

Answer 1

@BalusC已经给出了答案，但更明确地说，这里有一个来自Oracle的Java EE 6教程(你应该阅读(关于方法表达式的引用：

方法表达式只能在标记属性中使用，并且只能在 以下方式：

• 使用单个表达式构造，其中 bean 引用 JavaBeans 组件，方法引用 JavaBeans 的方法 元件：

  <some:tag value="#{bean.method}"/>

[...]

也就是说，将getCalculateTotalPrice重命名为calculateTotalPrice

编辑：以下方法调用的预期签名之间也存在不一致：

• <f:ajax listener="#{pricingCalculator.calculateTotalPrice} .../>期望MethodExpression参考javax.el.MethodNotFoundException明确规定的calculateTotalPrice(javax.faces.event.AjaxBehaviorEvent)方法

和

• <h:outputText value="#{pricingCalculator.calculateTotalPrice}"/>，它需要一个可以引用 Bean 属性或方法调用的返回值的java.lang.String。

在这里，<h:outputText>值可能意味着设置为 totalPrice 属性，因此它应该是：<h:outputText value="#{pricingCalculator.totalPrice}"/>