File decryption in webgame development

Hello everyone , I meet you again , I'm your friend, Quan Jun .

The last one is about file encryption , This article records how to load and display pictures .

Because the picture file is encrypted , Has become a binary stream file （ A lot of crap ）, Only use URLStream To load resources .

There is one caveat here ：URLStream The read operation in is non blocking , Must be used before reading data bytesAvailable Property to determine whether enough data can be obtained , How not to get enough data , Will lead to EOFError abnormal .

Main idea ：

1、 Load encrypted resources , Use URLStream

2、 Call decryption method , Get the decrypted data

3、 Use Loader Class loadBytes Method load resource

   1: var urlLoader:URLStream = new URLStream();

Copy

   2: var url:String = getEncryptURL(url);    // Through the resources that need to be loaded url, To get the address of the resource that needs to be loaded , Such as xx.png Actual will request xx.p

Copy

   3:  

Copy

   4: // monitor urlLoader Events 

Copy

   5: //Event.Complete、IOErrorEvent.IO_ERROR、ProgressEvent.PROGRESS、HTTPStatusEvent.HTTP_STATUS、Event.OPEN

Copy

   6:  

Copy

   7: var req:URLRequest = new URLRequest(url);

Copy

   8:  

Copy

   9: urlLoadedCount = 0;

Copy

  10:  

Copy

  11: urlLoader.load(req);

Copy

  12:  

Copy

  13:  

Copy

  14:  

Copy

  15:  

Copy

  16:  

Copy

  17: //onCompleteHandler In the method 

Copy

  18: var byte:ByteArray;

Copy

  19: var byteLen:int;

Copy

  20:  

Copy

  21: try 

Copy

  22: {

Copy

  23:     byteLen = urlLoader.bytesAvailable;

Copy

  24: }

Copy

  25: catch(e:Error)

Copy

  26: {

Copy

  27:     if (urlLoadedCount++ > 3)

Copy

  28:     {

Copy

  29:         return ;

Copy

  30:     }

Copy

  31:     

Copy

  32:     //reload  Reload , Until more than 3 Time 

Copy

  33:     

Copy

  34:     return ;

Copy

  35: }

Copy

  36:  

Copy

  37: urlLoadedCount = 0;

Copy

  38:  

Copy

  39: byte = new ByteArray();

Copy

  40: urlLoader.readBytes(byte, 0, byteLen);

Copy

  41: byte = EncryptUtils.DeEncrypt(byte); // Decrypt the data , It corresponds to the encryption method in the previous article 

Copy

  42: byte.position = 0;

Copy

  43:  

Copy

  44: // Start loading pictures 

Copy

  45: var loader = new Loader();

Copy

  46:  

Copy

  47: // monitor Event.Complete event 

Copy

  48: loader.contentLoaderInfo.removeEventListener(Event.COMPLETE, loadImgCompleteHandler);

Copy

  49:  

Copy

  50: var context:LoaderContext = new LoaderContext();

Copy

  51: context.applicationDomain = ApplicationDomain.currentDomain;

Copy

  52: context.securityDomain = SecurityDomain.currentDomain;

Copy

  53:  

Copy

  54: loader.loadBytes(byte, context);

Copy

  55:  

Copy

  56:  

Copy

  57: //loadImgCompleteHandler Method 

Copy

  58:  here loader.content Have been to Bitmap The class , Use addChild You can finish loading the picture 

Copy

  59:  

Copy

  60:  

Copy

  61: // If you want to load xml、txt And so on , This method is not required , Use byte.readUTFBytes(byte.bytesAvailable) You can get the decrypted string 

Copy

  62:  

Copy

More reference ：

flash.display.Loader>>

flash.display.Bitmap>>

flash.net.URLStream>>

Publisher ： Full stack programmer stack length , Reprint please indicate the source ：https://javaforall.cn/133958.html Link to the original text ：https://javaforall.cn