Flex——IDispose接口

前言

C/C++的开发，内存的管理是十分重要的课题，分配内存使用后要及时释放，否则内存泄漏导致内存耗尽。进入托管环境后，内存能够自动管理和回收，已经不用开发者太操心内存管理方面的问题了，在托管环境，开发者仍然可以做一些工作，提供内存回收的效率，例如，把类内部的引用对象设置为null是最基本的。借鉴在.net环境下的IDispose模式，现在，在Flex/AS3里实现。

IDispose接口

首先定义控制资源释放的接口。

package cwn.core

{

/*

* 释放资源接口

*/

public interface IDispose

{

function Dispose():void;

}

}

实现IDispose接口

public class ClassA implements cwn.core.IDispose

{

private var _RefObject:Object;//引用高级对象

public function ClassA()

{

}

private var _Disposed:Boolean = false;//释放控制标志

protected function Disposing():void

{

}

public function Dispose():void

{

if (_Disposed)

return;

Disposing();//释放派生类的资源

_RefObject = null; //释放ClassA资源

}

}

Disposing方法是派生类释放资源时按需要重写的，例如下面的ClassB

public class ClassB extends ClassA

{

private var _RefObject2:Object;

public function ClassB()

{

super();

}

override protected function Disposing():void

{

//释放ClassB资源

if(_RefObject2 is IDispose)

{

IDispose(_RefObject2).Dispose();

}

_RefObject2 = null;

super.Disposing();

}

}

DisposeUtil对象

定义一个资源释放的工具类，方便调用，集中释放。

package cwn.core

{

import flash.display.Bitmap;

import flash.display.DisplayObject;

import flash.display.MovieClip;

import flash.display.Sprite;

import flash.utils.Dictionary;

import mx.collections.ArrayCollection;

import mx.controls.SWFLoader;

public final class DisposeUtil

{

public static function Dispose(value:Object):void

{

if (value == null)

return;

if (value is Array)

{

ClearArray(value as Array);

}

else if (value is ArrayCollection)

{

ClearArrayCollection(value as ArrayCollection);

}

else if (value is SWFLoader)

{

DisposeSWFLoader(value as SWFLoader);

}

else if (value is Sprite)

{

DisposeSprite(value as Sprite);

}

else if (value is Dictionary)

{

ClearDictionary(value as Dictionary);

}

}

private static function ClearArray(value:Array):void

{

if (value == null)

return;

while (value.length > 0)

{

var child:IDispose = value.pop() as IDispose;

if (child != null)

child.Dispose();

}

}

private static function ClearArrayCollection(value:ArrayCollection):void

{

if (value == null)

return;

while (value.length > 0)

{

var child:IDispose = value.removeItemAt(0) as IDispose;

if (child != null)

child.Dispose();

}

}

private static function DisposeSprite(value:Sprite):void

{

if (value == null)

return;

while (value.numChildren > 0)

{

var child:DisplayObject = value.removeChildAt(0);

if (child is IDispose)

IDispose(child).Dispose();

}

}

private static function DisposeSWFLoader(value:SWFLoader):void

{

if (value == null)

return;

if (value.content is Bitmap)

{

Bitmap(value.content).bitmapData.dispose();

}

else if (value.content is MovieClip)

{

MovieClip(value.content).stop();

}

value.unloadAndStop(true);//flash player 10后支持

value.source = null;

}

private static function ClearDictionary(value:Dictionary):void

{

if (value == null)

return;

for each (var key:* in value)

{

var val:IDispose = value[key] as IDispose;

if (value != null)

val.Dispose();

delete value[key];

}

}

}

}