How to use MatrixToImageWriter.writeToStream() from javase in a server app

[George Vodarek]

I'm writing a web app to display a QR-code.   Here is the code:

BitMatrix bits = new QRCodeWriter().encode(otpURI, BarcodeFormat.QR_CODE, 200, 200);
ByteArrayOutputStream out = new ByteArrayOutputStream();
MatrixToImageWriter.writeToStream(bits, "PNG", out);
String qrCodeString = new Base64().encodeToString(out.toByteArray());

The first line creates a BitMatrix of the QR-code image.  The third line writes the bits to a stream so I can display it.  This works, BUT the writeToStream() call appears to launch a new Java App on my Mac, which is weird and undesirable.  It looks like this call launches a new process somehow, because when I quit that app it kills the original process.

What is the purpose of the javase.jar?  Perhaps I shouldn't be using it on the server?  Is there an alternative MatrixToImageWriter class elsewhere?

George.

[Sean Owen]

You're creating a new java process by running your program. That's what you see on OS X. Nothing here spawns a new process, no. javase.jar is just a jar full of the code you are calling. You can use it anywhere.

[Lachezar Dobrev]

Try starting the 'server' with -Djava.awt.headless=true

2013/6/28 George Vodarek <gvod...@pingidentity.com>:

[George Vodarek]

Thanks, Lachezar.  I'll try that.  The thing is I'm running a web app on the Jetty server started it from the command line.  The other thing is that this only appears to happen on a Mac.  In Windows and Linux I don't see that new app start up.  Strange.

George.

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[Sean Owen]

Do you really mean your Java based web app starts a whole new Java process? That's completely unnecessary.

But if you do that it is starting a new process on every platform. Its just that OS X puts an icon on it.