Databases
StackOverflow2013
Postsdbo
POEncoding and decoding byte[] with ZXing
Body
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POEncoding and decoding byte[] with ZXing
    text
    copied!<p>I am developping an Android app, and I need to encode and decode a bytes array in a QRCode generated with the ZXing app. My problem is that my message decoded does not exactly match the generated byte array. I tried to create a QRCode based on a byte array containing incrementing indexes, i.e.</p> <pre><code>input = [0, 1, 2, ..., 124, 125, 126, 127, -128, -127,... -3, -2, -1, 0, 1, 2, ...] </code></pre> <p>And after encoding the message in the QRCode and decoding it on the responder side, I obtain the following byte array output:</p> <pre><code>output = [0, 1, 2, ..., 124, 125, 126, 127, 63, 63,... 63, 63, 63, 0, 1, 2, ...] </code></pre> <p>All the "negative" byte values are turned to ASCII char 63: '?' question mark characters. I assume that something is going wrong with the encoding charset, but since I am using ISO-8859-1 which everyone claims to be the solution of such kind of issue (<a href="https://stackoverflow.com/a/2489611/1424133">other topic treating the same kind of issue</a> or <a href="http://code.google.com/p/zxing/issues/detail?id=103" rel="nofollow noreferrer">here</a>), I don't see where is my mistake, or if I am skipping a step during the instanciation of the encoding or the decoding. Here is the code that I execute to encode a given byte array:</p> <pre class="lang-java prettyprint-override"><code>String text = ""; byte[] res = new byte[272]; for (int i = 0; i &lt; res.length; i++) { res[i] = (byte) (i%256); } try { text = new String(res, "ISO8859_1"); } catch (UnsupportedEncodingException e) { // TODO } Intent intent = new Intent(Intents.Encode.ACTION); Intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET); intent.putExtra(Intents.Encode.TYPE, Contents.Type.TEXT); intent.putExtra(Intents.Encode.FORMAT, "ISO8859_1"); intent.putExtra(Intents.Encode.DATA, text); intent.putExtra(Intents.Encode.FORMAT, BarcodeFormat.QR_CODE.toString()); boolean useVCard = intent.getBooleanExtra(USE_VCARD_KEY, false); QRCodeEncoder qrCodeEncoder = new QRCodeEncoder(activity, intent, dimension, useVCard); Bitmap bitmap = qrCodeEncoder.encodeAsBitmap(); </code></pre> <p>And to decode a QRCode, I send the following Intent</p> <pre class="lang-java prettyprint-override"><code>@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.qrcodeDecoding); Intent intent = new Intent(Intents.Scan.ACTION); intent.putExtra(Intents.Scan.MODE, Intents.Scan.QR_CODE_MODE); startActivityForResult(intent, 0); } </code></pre> <p>And wait for Result:</p> <pre class="lang-java prettyprint-override"><code>@Override protected void onActivityResult(int request, int result, Intent data) { if(request == 0) { //action if(result == RESULT_OK) { String res = data.getStringExtra(Intents.Scan.RESULT); byte[] dat = null; try{ dat = res.getBytes("ISO8859_1"); } catch(UnsopportedEncodingException e) { //TODO } } else if(result == RESULT_CANCELED) { //TODO } } } </code></pre> <p>Could you please tell me where are my mistakes, or where should I look at?</p> <p>Thank you a lot,</p> <p>Franck</p>
 

Querying!

 
Guidance
An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload