flex 显示图片二进制流

Flex一般情况下是用Image控件通过source属性和load方法加载文件或URL图片，Image控件允许您在运行时导入?JPEG、PNG、GIF?和?SWF?文件。

注意：不支持bmp格式的文件，要想显示bmp，一般是将BMP图片转换成二进制，再转成BitmapData，最后把获取位图数据的Bitmap传给Image源，让Image控件显示出来。

Image组件的source属性是不支持二进制数据的，我们可以自己定义一个组件用于显示二进制图片数据流。网上也有很多相关的例子，但是有些是不能直接改变图片大小，直接根据二进制图片原始大小显示，我根据相关代码修改了一下，可以实现缩放比例显示，已经固定了图片大小。

代码：

?

package?com.image

{

????import?flash.display.Loader;

????import?flash.events.Event;

????import?flash.system.LoaderContext;

????import?flash.utils.ByteArray;

????import?mx.controls.Image;

????/**

?????*?用来加载二进制数据的图片类

?????* */

????publicclass?ByteArrayImage?extends?mx.controls.Image

????{

???????privatevar?_loader:Loader =?new?Loader();

???????var?_bonthebl:Boolean=true;//是否按照比例缩放全图显示。

???????var?_bFillUp:Boolean =?false;??是/否平铺

???????publicfunction?Image():void?{}

???????overrideprotectedfunction?createChildren():void

???????{

???????????addChild(_loader);

???????}

??????

???????function?loadBytes(bytes:ByteArray,context:LoaderContext=null):void

???????{

???????????_loader.loadBytes(bytes,context);

???????????_loader.contentLoaderInfo.addEventListener(Event.COMPLETE,onBytesLoaded);

???????}

???????functionget?bFillUp():Boolean{

???????????return?_bFillUp;

???????}

??????

???????set?bFillUp(value:Boolean):void{

???????????this._bFillUp = value;

???????}

???????get?bonthebl():Boolean{

???????????return?_bonthebl;

???????}

??????

???????set?bonthebl(value:Boolean):this._bonthebl = value;

???????}

???????privatefunction?onBytesLoaded(e:Event):void

???????{

???????/*??this.width = e.target.width;

???????????this.height = e.target.height;*/

???????????this.width=150;

???????????this.height=200;

???????????if(_bonthebl){

??????????????var?ih:int=e.currentTarget.height;

??????????????var?iw:int=e.currentTarget.width;

??????????????var?blh:Number=this.height/ih;

??????????????var?blw:Number=this.width/iw;

??????????????if(blh>1&&blw>1){

??????????????????_loader.width=e.currentTarget.width;

??????????????????_loader.height=e.currentTarget.height;

??????????????}

??????????????elseif(blh>1||blw>1){

??????????????????if(blh<1){

?????????????????????_loader.width = Math.round(iw*blh);

?????????????????????_loader.height =?this.height;

??????????????????}else{

?????????????????????_loader.width =?this.width;

?????????????????????_loader.height = Math.round(ih*blw);

??????????????????}

??????????????}else{

??????????????????if(blh>blw){

?????????????????????_loader.width = Math.round(iw*blw);

?????????????????????_loader.height = Math.round(ih*blw);

??????????????????}

??????????????????else{

?????????????????????_loader.width = Math.round(iw*blh);

?????????????????????_loader.height = Math.round(ih*blh);

??????????????????}

??????????????}

??????????????this.width=_loader.width;

??????????????this.height=_loader.height;

???????????}

???????????if(_bFillUp)

???????????{

??????????????_loader.width =?this.width;

??????????????_loader.height =?this.height;

???????????}?

???????}

????}

?

}

页面调用的部分代码：

???????? <img:ByteArrayImage id="img"? />

???????img.loadBytes(“二进制数据流”);

?后台相关代码省略。

一般情况下，数据库的blob字段映射为java.sql.blob类型。所以在后台将blob转换为byte数据类型，转换的相关代码

/***

用于将从数据库中读取的二进制文件流转换为byte数组

?????*/

????publicbyte[] getByteFromStream(InputStream is) {

???????byte[] b =?newbyte[1];

???????try?{

???????????ByteArrayOutputStream bytestream =?new?ByteArrayOutputStream();

???????????//?创建数据读取缓存byte数组

???????????byte[] buffer =?byte[2048];

???????????int?temp;

???????????if?(is ==?null)

??????????????returnnull;

???????????temp = is.read(buffer);

???????????while?(temp != -1) {

??????????????bytestream.write(buffer,temp);

??????????????temp = is.read(buffer);

???????????}

???????????将ByteArrayOutputStream转换为二进制数组

???????????b = bytestream.toByteArray();

???????????is.close();

?

???????}?catch?(Exception e) {

???????????e.printStackTrace();

???????}

???????return?b;

????}

?

?

????public?InputStream getStreamFromByte(byte?img[]) {

???????new?ByteArrayInputStream(img);

????}