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Invoke JSF managed bean action on page load

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别跟我提以往
别跟我提以往 2020-11-22 13:16

Is there a way to execute a JSF managed bean action when a page is loaded?

If that\'s relevant, I\'m currently using JSF 1.2.

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  • 没有蜡笔的小新
    2020-11-22 13:42

    Another easy way is to use fire the method before the view is rendered. This is better than postConstruct because for sessionScope, postConstruct will fire only once every session. This will fire every time the page is loaded. This is ofcourse only for JSF 2.0 and not for JSF 1.2.

    This is how to do it -

    <html xmlns:f="http://java.sun.com/jsf/core">
      <f:metadata>
          <f:event type="preRenderView" listener="#{myController.onPageLoad}"/>
      </f:metadata>
</html>

    And in the myController.java

     public void onPageLoad(){
    // Do something
 }

    EDIT - Though this is not a solution for the question on this page, I add this just for people using higher versions of JSF.

    JSF 2.2 has a new feature which performs this task using viewAction. 

    <f:metadata>
    <f:viewAction action="#{myController.onPageLoad}" />
</f:metadata>
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  • 挽巷
    2020-11-22 13:44

    calling bean action from a will be a good idea,keep attribute autoRun="true" example below

    <p:remoteCommand autoRun="true" name="myRemoteCommand" action="#{bean.action}" partialSubmit="true" update=":form" />
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  • 南笙
    2020-11-22 13:50

    JSF 1.0 / 1.1

    Just put the desired logic in the constructor of the request scoped bean associated with the JSF page. 

    public Bean() {
    // Do your stuff here.
}

    JSF 1.2 / 2.x

    Use @PostConstruct annotated method on a request or view scoped bean. It will be executed after construction and initialization/setting of all managed properties and injected dependencies.

    @PostConstruct
public void init() {
    // Do your stuff here.
}

    This is strongly recommended over constructor in case you're using a bean management framework which uses proxies, such as CDI, because the constructor may not be called at the times you'd expect it.

    JSF 2.0 / 2.1

    Alternatively, use <f:event type="preRenderView"> in case you intend to initialize based on <f:viewParam> too, or when the bean is put in a broader scope than the view scope (which in turn indicates a design problem, but that aside). Otherwise, a @PostConstruct is perfectly fine too.

    <f:metadata>
    <f:viewParam name="foo" value="#{bean.foo}" />
    <f:event type="preRenderView" listener="#{bean.onload}" />
</f:metadata>

    public void onload() { 
    // Do your stuff here.
}

    JSF 2.2+

    Alternatively, use <f:viewAction> in case you intend to initialize based on <f:viewParam> too, or when the bean is put in a broader scope than the view scope (which in turn indicates a design problem, but that aside). Otherwise, a @PostConstruct is perfectly fine too.

    <f:metadata>
    <f:viewParam name="foo" value="#{bean.foo}" />
    <f:viewAction action="#{bean.onload}" />
</f:metadata>

    public void onload() { 
    // Do your stuff here.
}

    Note that this can return a String navigation case if necessary. It will be interpreted as a redirect (so you do not need a ?faces-redirect=true here).

    public String onload() { 
    // Do your stuff here.
    // ...
    return "some.xhtml";
}

    See also:

    • How do I process GET query string URL parameters in backing bean on page load?
    • What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?
    • How to invoke a JSF managed bean on a HTML DOM event using native JavaScript? - in case you're actually interested in executing a bean action method during HTML DOM load event, not during page load.
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  • 梦毁少年i
    2020-11-22 14:02

    @PostConstruct is run ONCE in first when Bean Created. the solution is create a Unused property and Do your Action in Getter method of this property and add this property to your .xhtml file like this :

    <h:inputHidden  value="#{loginBean.loginStatus}"/>

    and in your bean code:

    public void setLoginStatus(String loginStatus) {
    this.loginStatus = loginStatus;
}

public String getLoginStatus()  {
    // Do your stuff here.
    return loginStatus;
}
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