Check remote file existance with Flex 3

Question

In Flex 3/AS 3, what would be a good way to check if a remote file exists? I'm thinking in PHP ways where you'd try to "fopen" a remote path (like "http://example.com/somefile.exe"), and see if it works or not. I'm not asking to just download all of the file, I just want to know if the file is there (and accessible).

Answer 1

You would probably need to attempt to load the file. If you get an IOError, the file doesn't exist (or your path is wrong). If it starts loading, by triggering a progress event then it exists. You can then cancel the remainder of the loading.

Alternatively you could try calling a PHP script from Flash which does what you have described, this could return a simple true/false.

Answer 2

This is the best code I found for the job

var urlStream:URLStream = new URLStream();
urlStream.addEventListener(Event.OPEN, streamHandler);
urlStream.addEventListener(IOErrorEvent.IO_ERROR, streamHandler);
urlStream.load(new URLRequest("SOME_FILE"));

function streamHandler(e:Event):void {
    urlStream.close();
    if(e.type == Event.OPEN){
        trace("FILE EXISTS");
    } else if(e.type == IOErrorEvent.IO_ERROR){
        trace("FILE DOES NOT EXIST");
    }
}

Answer 3

There is a utility class I developed that handle a check weather a file exists or not. Here's the code: https://github.com/eladelrom/eladlib/blob/master/EladLibFlex/src/com/elad/framework/utils/FileExistsUtil.as

And implementation looks like this:

var fileExists:FileExistsUtil = new FileExistsUtil();
fileExists.checkFile("file.jpg", 
function(eventType:String):void
{
 trace(eventType);
}, 
function(errorType:String, text:String):void
{
 trace(errorType+": "+text);
});