JSF difference between action, actionlistener, onClick [duplicate]

问题

This question already has answers here:

Differences between action and actionListener (4 answers)

How to invoke a bean action method using a link? The onclick does not work (3 answers)

Closed 2 years ago.

I am using JSF in my project. I am using a context menu from PrimeFaces. I see in p:menuItem we have action, actionListener, onclick methods. So my question is: When do I have to use action, actionListner, onclick and what is the order of execution?

回答1:

• onclick will be executed first. It is used to call a javascript function.

• actionListener is used when you want to have some ajax call to a
  method. That method should have the return type void, the method either take an ActionEvent as argument or no argument; it can also be used for a non-ajax call but then the page will be refreshed.

• action is used to navigate to a different page; the method should have the return type String.

回答2:

This question has been asked before. Action is used when you want to call a method in your backing bean. e.g

action="#{myBean.myMethod}"

the code for bean would be like

@ManagedBean(name = "myBean", eager = true)
@ViewScoped
public class MyBean{

myMethod(){
// your method code here
}

}

How ever action listener does the same except that it is triggered with an event

myMethod(Event e){
// your method code here
}

Note that event can be of any type.

onclick works before sending the ajax request i dont have much knowlegde aboput it... i only used it for the UI purposes for example closing a dialog box on clicking a button

<p:commandButton id="cancel"  value="Cancel"
                                    icon="ui-icon ui-icon-arrowreturnthick-1-w"
                                    style="float:right;" onclick="PF("dlg").hide()" type="button">
                                </p:commandButton>

SEE ALSO

Differences between action and actionListener

来源：https://stackoverflow.com/questions/21438721/jsf-difference-between-action-actionlistener-onclick