what is differences between action and actionlistener in JSF components?-优快云博客

本文探讨了JavaServer Faces (JSF) 中的Action与Action Listener的区别与应用场景。Action方法通常用于按钮或链接点击后的业务逻辑处理，并可能根据执行结果进行页面导航；而Action Listener则用于执行一些不需要导航的操作，如响应复选框点击改变页面元素的显示状态。

Following refer to the Faces event model.

Basically the "action" attribute refers to an action method which returns a String from which the Faces navigation model can use to decide whether or not a navigation is necessary based on the value of the string.

typically one uses an action method to execute some code after a button or link is clicked and then possibly navigate based on the outcome of executed code.

An actionlistener method compared to an action method does not return a String. Instead it returns void. It is basically identical to the action method but instead it just executes the code after an action event (button click or link click) but a navigation is not needed.

A good example of actionlistener could be in response to clicking on a checkbox and having the actionlistener code behind it change a visual attribute of a page such as render a component that was not rendered before..

Chapter 8 has exactly this example where I show how you can have a checkbox when clicked render an additional field in an input form.

So. we just need to remember :

　　　　action:MethodExpression representing the application action to invoke when this component is activated by
the user. The expression must evaluate to a public method that takes no parameters, and returns an
Object (the toString() of which is called to derive the logical outcome) which is passed to the
NavigationHandler for this application.

　　　　actionlistener .MethodExpression representing an action listener method that will be notified when this component
is activated by the user. The expression must evaluate to a public method that takes an
ActionEvent parameter, with a return type of void.

2.singel page ,and it refresh itself and don't direct or skip to next page , using actionlistener better .

direct or skip ,keep using action first .

3.
action : No paramters ,have return values

actionlistener :ActionEvent parameter, No return value (void) , can't navigation-rule