flex初始化reasearch.doc

尊重版权:/actruel/program/20110913/flex-research.html后来研究发现，不是取不到，而是在createChildren的时候，自定义的objcet还没有被赋值，只有当该组件的init事件之后才会被赋值，代码如下：APP:复制代码 代码如下:CustomPanel：复制代码 代码如下:package comimport mx.containers.Panel;import mx.events.FlexEvent;public class CustomPanel extends Panelpublic function CustomPanel()super();this.addEventListener(FlexEvent.PREINITIALIZE, onPreInit);this.addEventListener(FlexEvent.INITIALIZE, onInit);this.addEventListener(FlexEvent.CREATION_COMPLETE, onCreationComplete);this.addEventListener(FlexEvent.APPLICATION_COMPLETE, onAppInitComplete);/=/ event handler/=private function onPreInit(event:FlexEvent):voidtrace(CustomPanel PreInit );private function onInit(event:FlexEvent):voidtrace(CustomPanel Init );private function onCreationComplete(event:FlexEvent):voidtrace(CustomPanel CreationComplete );private function onAppInitComplete(event:FlexEvent):voidtrace(CustomPanel AppInitComplete );/=/ override function/=override protected function createChildren():voidtrace(CustomPanel Begin to createChildren );super.createChildren();trace(CustomPanel The end of createChildren );override protected function measure():voidtrace(CustomPanel Begin to measure );super.measure();trace(CustomPanel The end of measure );override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):voidtrace(CustomPanel Begin to updateDisplayList );super.updateDisplayList(unscaledWidth, unscaledHeight);trace(CustomPanel The end of updateDisplayList );override protected function layoutChrome(unscaledWidth:Number, unscaledHeight:Number):voidtrace(CustomPanel Begin to layoutChrome );super.layoutChrome(unscaledWidth, unscaledHeight);trace(CustomPanel The end of layoutChrome );override protected function commitProperties():voidtrace(CustomButton Begin to commitProperties );mitProperties();trace(CustomButton The end of commitProperties );CustomButton：复制代码 代码如下:package comimport mx.controls.Button;import mx.events.FlexEvent;public class CustomButton extends Button/=/ properties/=private var _customString:String = ;private var _customObject:Object = null;public function get customString():Stringreturn _customString;/stringpublic function set customString(value:String):voidtrace(CustomButton( set customString );_customString = value;/objectpublic function get customObject():Objectreturn _customObject;public function set customObject(value:Object):voidtrace(CustomButton( set customObject );_customObject = value;/=/ Constructor/=public function CustomButton()trace(CustomButton( Begin to Constructor );super();this.addEventListener(FlexEvent.PREINITIALIZE, onPreInit);this.addEventListener(FlexEvent.INITIALIZE, onInit);this.addEventListener(FlexEvent.CREATION_COMPLETE, onCreationComplete);this.addEventListener(FlexEvent.APPLICATION_COMPLETE, onAppInitComplete);trace(CustomButton( The end of Constructor );/=/ event handler/=private function onPreInit(event:FlexEvent):voidtrace(CustomButton( PreInit );private function onInit(event:FlexEvent):voidtrace(CustomButton( Init );private function onCreationComplete(event:FlexEvent):voidtrace(CustomButton( Creation Complete );private function onAppInitComplete(event:FlexEvent):voidtrace(CustomButton( AppInitComplete );/=/ override function/=override protected function createChildren():voidtrace(CustomButton( Begin to createChildren );super.createChildren();trace(CustomButton( The end of createChildren );override protected function measure():voidtrace(CustomButton( Begin to measure );super.measure();trace(CustomButton( The end of measure );override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):voidtrace(CustomButton( Begin to updateDisplayList );super.updateDisplayList(unscaledWidth, unscaledHeight);trace(CustomButton( The end of updateDisplayList );override protected function commitProperties():voidtrace(CustomButton( Begin to commitProperties );mitProperties();trace(CustomButton( The end of commitProperties );最后运行的结果是：CustomPanel PreInit CustomPanel Begin to createChildren CustomButton( Begin to Constructor )CustomButton( The end of Constructor )CustomButton( set customString ) /基本变量（String，Number（int，uint），Boolean）在PreInit 之前就被赋值CustomButton( PreInit )CustomButton( Begin to createChildren )CustomButton( The end of createChildren )CustomButton( Init )CustomButton( set customObject ) /自定义对象变量在 Init之后才能被赋值，所以在createChildren中取不到CustomPanel Init /有子控件的时候，Init 事件是在createChildren中发出的CustomPanel The end of createChildren CustomButton( set customObject )CustomButton Begin to commitProperties CustomButton The end of commitProperties CustomButton( Begin to commitProperties )CustomButton( The end of commitProperties )CustomButton( Begin to measure )CustomButton( The end of measure )CustomPanel Begin to measure CustomPanel The end of measure CustomPanel Begin to updateDisplayList CustomPanel Begin to layoutChrome CustomPanel The end of layoutChrome /证明layoutChrome是在updateDisplayList 中被调用的CustomPanel The end of updateDisplayList CustomButton( Begin to updateDisplayList )CustomButton( The end of updateDisplayList )CustomButton( Creation Complete )CustomPanel CreationComplete 后来又发现，在MXML中设置基本变量和对象变量有一定区别，那就是对象变量必须要用大括号包起来，于是就想，会不会是绑定造成的，将APP改成如下,发现跟预想中的一样，最后的输出结果与上面的一样：复制代码 代码如下:为了进一步确定是由于绑定造成的赋值时期不一致，我又做了如下的一个试验，不使用绑定给对象变量赋值：复制代码 代码如下:其结果为:CustomPanel PreInit CustomPanel Begin to createChildren CustomButton( Begin to Constructor )CustomButton( The end of Constructor )CustomButton( set customString )CustomButton( set customObject ) /赋值时间与基本变量相同CustomButton( PreInit )CustomButton( Begin to createChildren )CustomButton( The end of createChildren )CustomButton( Init )CustomPanel Init CustomPanel The end of createChildren CustomButton Begin to commitProperties CustomButton The end of commitProperti