1

目前我正在学习 RichFaces 并阅读了一些现场演示，http://livedemo.exadel.com/richfaces-demo/richfaces/commandButton.jsf?c=commandButton&tab=usage

<ui:composition xmlns="http://www.w3.org/1999/xhtml"
  xmlns:ui="http://java.sun.com/jsf/facelets"
  xmlns:h="http://java.sun.com/jsf/html"
  xmlns:f="http://java.sun.com/jsf/core"
  xmlns:a4j="http://richfaces.org/a4j"
  xmlns:rich="http://richfaces.org/rich">

<style>
    .gridhello {
        border-collapse : collapse;
    }
    .gridhellocolumn {
        padding-left : 0;
    }
    .outhello {
        font-weight: bold;
    }
</style>

<a4j:form>
    <h:panelGrid columns="3" styleClass="gridhello" columnClasses="gridhellocolumn">
        <h:outputText value="Name:" />
        <h:inputText value="#{userBean.name}" />
        **<a4j:commandButton value="Say Hello" reRender="out" />**
    </h:panelGrid>
</a4j:form>
<rich:spacer height="7"/>
<br />
<h:panelGroup id="out">
    <h:outputText value="Hello " rendered="#{not empty userBean.name}" styleClass="outhello" />
    <h:outputText value="#{userBean.name}" styleClass="outhello" />
    <h:outputText value="!" rendered="#{not empty userBean.name}" styleClass="outhello" />
</h:panelGroup>

<br />

代码行没有“action”属性，我只是想知道它是如何工作的，在这种情况下调用 back bean 的默认方法是什么，以便更新 userBean.name？

提前致谢！

4

1 回答 1

3

When you do a submit, the form data is sent into the mapped attributes of the managed bean. That's default behavior for UICommands: <h:commandButton>, <h:commandLink>, <a4j:commandButton>, <a4j:commandLink> and others like <a4j:jsFunction>. Even if you don't declare an action to execute, the form data is submitted to the server through a POST request and the JSF lifecycle will fire. As part of the lifecycle, in the Update Model phase, JSF will set the data bound from the components into the managed bean attributes, then the Invoke Applications phase will perform any action (if available) and in the end the Render Response phase will generate the response and update the View (JSP, Facelets). In this case, since it's an ajax call, the view will be updated; more exactly, the component with id "out" will be updated. Note that this "out" content is outside the <a4j:form>, the values here won't be sent to server, still the reRender will update their values with the view model values.

UPDATE:

The line <h:inputText value="#{userBean.name}" is binding the name attribute of the UserBean managed bean with the value of the <h:inputText> component. This is a basic concept from JSF. Remember that RichFaces is not a JSF implementation, it extends the framework and add functionalities like ajax support for RIA.

This line

<h:outputText value="#{userBean.name}" styleClass="outhello" />

means: bind the value of name attribute of the UserBean managed bean to the outputText component. Still, this is outside the form, so the actual value of this component won't be sent on the server.

Some resorces to learn more about JSF:

于 2012-07-20T14:15:21.163 回答