Question

I’ve done it this way, but Adobe Air hangs for several seconds.

        private function test():void
        {
            fileStream = new FileStream(); 
            fileStream.addEventListener(IOErrorEvent.IO_ERROR, fileError);
            fileStream.addEventListener(Event.COMPLETE, opened);
            fileStream.openAsync(filePath, FileMode.READ);
        }

        protected function opened(event:Event):void
        {
            var bytes:ByteArray = new ByteArray();
            fileStream.readBytes(bytes);
            fileStream.close();
            // MD5Stream from package com.adobe.crypto.MD5Stream  https://github.com/mikechambers/as3corelib/blob/master/src/com/adobe/crypto/MD5Stream.as
            var md5stream:MD5Stream = new MD5Stream;
            trace(md5stream.complete(bytes)); // md5    
        }

How to make the process of getting md5 without hanging?

Answer 1

Try using Bloody’s MD5 implementation. It’s apparently a lot faster.

While it will speed up the hash calculation, perhaps even adequately, you’re not really solving the underlying problem, which is that you want a non-blocking operation in a single threaded application model. In Flash/AIR, this is generally done by breaking the work up into smaller chunks, and doing only one chunk’s worth of processing each frame, instead of all at once during one frame. There’s even a cool framework to simplify this!

I noticed that the library you’re currently using, MD5Stream, is built for incremental updates — so you can easily feed it little chunks of the file each frame until the entire file is processed. This will allow the frame rate to stay relatively constant while the hash is computed.