flex4学习笔记_events

Summary for events in flex4

(英语摘自原文，这个貌似只适合我自己看。。。) 

In this chapter, I described the Flex event architecture and how you can create your own events to

share data between application components. You learned the following:

 

● a Flex applications are event-driven.

 

● Every component that dispatches events includes EventDispatcher in its inheritance hierarchy.

 

● You handle events with either MXML-based event handlers or the addEventListener() method.

    调用event的处理函数一般有两种方式(MXML-based & AS)，比如

<components:LoginForm login=”loginHandler(event)”/>

等同于

myForm.addEventListener(LoginEvent.LOGIN, loginHandler); //LoginEvent.LOGIN就是String("login")

    这里的login对应于自定义组件LoginForm中的元数据声明

<fx:Metadata>

[Event(name=”login”, type=”events.LoginEvent”)]

</fx:Metadata>

    类似的，Button也是一个组件，click就对应于login

<s:Button id="myButton" label="Click me" click="clickHandler(event)">

或者 myButton.addEventListener(MouseEvent.CLICK, clickHandler);

//这里clickHanlder不需要参数  

 

● Event handler functions receive a single event argument and return void.

 

● Flash Builder 4 adds the capability to generate event handler functions for all Flex components and events.

    这点确实好用，bible这本书上有详细的介绍

 

● You can declare and dispatch custom events from your custom components.

 

● You can create custom event classes to store and send data from custom components to the rest of the application.

    在我看来，这点比较适用于数据交换、传递。在组件内监听一个事件，进行一些处理，把结果保存在event的属性上，比如event.text，在组件外可以通过handler function把这个属性传递给其他的组件属性。

 

● To make a custom event class bubble, set its bubbles property to true.

    在我的理解，各个“容器”“从小到大”，依次响应event，比如click(如果设有handler function)

 

● Override the Event class’s clone() method if you want to be able to re-dispatch custom event objects from an event handler method.

    这点不知道实际用途有哪些。。。

 

● You handle custom events and event classes with the same architecture as pre-built classes that are included in the Flex SDK.

    这个就如同上面的类比