actionscript 3: Check if an external file exists and if so unhide a movieClip

问题

I'm trying to check if an external file exists and if so change the value of the visibility of a certain movie clip to true. I know how to do it in AS2, but I'm working in AS3.

This is the AS2 code that I used to work with:

onClipEvent (load) {
    fileExists = new LoadVars();

    fileExists._parent = this;

    fileExists.onLoad = function(success) {

        //success is true if the file exists, false if it doesnt

        if (success) {
            _root.visiblity = 1;

            //the file exists
        }

    };

    fileExists.load('visibility.exe');//initiate the test}
}

How to make it work in AS3? Thanks!

回答1:

Class flash.net.URLLoader. From Adobe ActionScript 3.0 Reference:

var urlRequest:URLRequest = new URLRequest("visibility.exe");
var urlLoader:URLLoader = new URLLoader();
urlLoader.dataFormat = URLLoaderDataFormat.BINARY;
urlLoader.addEventListener(Event.COMPLETE, urlLoader_complete);
urlLoader.addEventListener(IOErrorEvent.IO_ERROR, urlLoader_error);
urlLoader.load(urlRequest);

function urlLoader_complete(evt:Event):void {
   trace("file found");
}

function urlLoader_error(evt:IOErrorEvent):void {
   trace("file obviously not found");
}

Don't forget to import required classes.

回答2:

A different way to do it in AS3 (the example assumes that you are searching for the file in the user's documents dir, change it accordingly):

var tmp_file:File = File.documentsDirectory.resolvePath('my_file.txt');

if (tmp_file.exists) {
    // File exists
} else {
    // File doesn't exist
}

回答3:

var tmp_file:File = File.documentsDirectory.resolvePath('my_file.txt');

if (tmp_file.exists) {
    // File exists
} else {
    // File doesn't exist
}

"Keep it simple stupid" - Kiss

Thanks for this code I was struggling with

 .addEventListener(Event.COMPLETE, Myfunction)

not firing half the time when in an MC or timeline and not at all when in a class or any included code.

I recommend the Above code if you just want to see if a file is there or not. If your using air for android you can use:

File.applicationStorageDirectory.resolvePath("my_file.txt");

To store to native Appdata directory.

来源：https://stackoverflow.com/questions/17081749/actionscript-3-check-if-an-external-file-exists-and-if-so-unhide-a-movieclip

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actionscript-3

file-exists