class="htmledit_views">

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class="tags" href="/tags/NULL.html" title=null>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

    {

        class="tags" href="/tags/FUNCTION.html" title=function>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 class="tags" href="/tags/FUNCTION.html" title=function>function ClassA()

    {

    }

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

    protected class="tags" href="/tags/FUNCTION.html" title=function>function Disposing():void

    {

    }

    public class="tags" href="/tags/FUNCTION.html" title=function>function Dispose():void

    {

        if (_Disposed)

            return;

        Disposing();//释放派生类的资源

        _RefObject = class="tags" href="/tags/NULL.html" title=null>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 class="tags" href="/tags/FUNCTION.html" title=function>function ClassB()

    {

        super();

    }

    override protected class="tags" href="/tags/FUNCTION.html" title=function>function Disposing():void

    {

        //释放ClassB资源

        if(_RefObject2 is IDispose)

        {

            IDispose(_RefObject2).Dispose();

        }

        _RefObject2 = class="tags" href="/tags/NULL.html" title=null>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

{

    class="tags" href="/tags/IMPORT.html" title=import>import flash.display.Bitmap;

    class="tags" href="/tags/IMPORT.html" title=import>import flash.display.DisplayObject;

    class="tags" href="/tags/IMPORT.html" title=import>import flash.display.MovieClip;

    class="tags" href="/tags/IMPORT.html" title=import>import flash.display.Sprite;

    class="tags" href="/tags/IMPORT.html" title=import>import flash.utils.Dictionary;

    class="tags" href="/tags/IMPORT.html" title=import>import mx.collections.ArrayCollection;

    class="tags" href="/tags/IMPORT.html" title=import>import mx.controls.SWFLoader;

 

    public final class DisposeUtil

    {

        public static class="tags" href="/tags/FUNCTION.html" title=function>function Dispose(value:Object):void

        {

            if (value == class="tags" href="/tags/NULL.html" title=null>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 class="tags" href="/tags/FUNCTION.html" title=function>function ClearArray(value:Array):void

        {

            if (value == class="tags" href="/tags/NULL.html" title=null>null)

                return;

            while (value.length > 0)

            {

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

                if (child != class="tags" href="/tags/NULL.html" title=null>null)

                    child.Dispose();

            }

        }

        private static class="tags" href="/tags/FUNCTION.html" title=function>function ClearArrayCollection(value:ArrayCollection):void

        {

            if (value == class="tags" href="/tags/NULL.html" title=null>null)

                return;

            while (value.length > 0)

            {

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

                if (child != class="tags" href="/tags/NULL.html" title=null>null)

                    child.Dispose();

            }

        }

        private static class="tags" href="/tags/FUNCTION.html" title=function>function DisposeSprite(value:Sprite):void

        {

            if (value == class="tags" href="/tags/NULL.html" title=null>null)

                return;

            while (value.numChildren > 0)

            {

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

                if (child is IDispose)

                    IDispose(child).Dispose();

            }

        }

        private static class="tags" href="/tags/FUNCTION.html" title=function>function DisposeSWFLoader(value:SWFLoader):void

        {

            if (value == class="tags" href="/tags/NULL.html" title=null>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 = class="tags" href="/tags/NULL.html" title=null>null;

        }

        private static class="tags" href="/tags/FUNCTION.html" title=function>function ClearDictionary(value:Dictionary):void

        {

            if (value == class="tags" href="/tags/NULL.html" title=null>null)

                return;

            for each (var key:* in value)

            {

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

                if (value != class="tags" href="/tags/NULL.html" title=null>null)

                    val.Dispose();

                delete value[key];

            }

        }

    }

}