QR Code encoding and decoding using zxing

Question

Okay  so I m going to take the off chance that someone here has used zxing before  I m developing a Java application  and one of the things it needs to do is encode a byte array of data into a QR Code and then decode it at a later time     Here s an example of what my encoder looks like   byte   b    0x48  0x45  0x4C  0x4C  0x4F     convert the byte array into a UTF-8 string String data  try       data   new String b   UTF8      catch  UnsupportedEncodingException e       the program shouldn t be able to get here  return       get a byte matrix for the data ByteMatrix matrix  com google zxing Writer writer   new QRCodeWriter    try    matrix   writer encode data  com google zxing BarcodeFormat QR CODE  width  height     catch  com google zxing WriterException e       exit the method  return       generate an image from the byte matrix int width   matrix getWidth     int height   matrix getHeight      byte     array   matrix getArray       create buffered image to draw to BufferedImage image   new BufferedImage width  height  BufferedImage TYPE INT RGB      iterate through the matrix and draw the pixels to the image for  int y   0  y  lt  height  y        for  int x   0  x  lt  width  x         int grayValue   array y  x   amp  0xff     image setRGB x  y   grayValue    0   0   0xFFFFFF            write the image to the output stream ImageIO write image   png   outputStream     The beginning byte array in this code is just used to test it  The actual byte data will be varied   Here s what my decoder looks like     get the data from the input stream BufferedImage image   ImageIO read inputStream      convert the image to a binary bitmap source LuminanceSource source   new BufferedImageLuminanceSource image   BinaryBitmap bitmap   new BinaryBitmap new HybridBinarizer source       decode the barcode QRCodeReader reader   new QRCodeReader     Result result  try    result   reader decode bitmap  hints     catch  ReaderException e       the data is improperly formatted  throw new MCCDatabaseMismatchException       byte   b   result getRawBytes    System out println ByteHelper convertUnsignedBytesToHexString result getText   getBytes  UTF8      System out println ByteHelper convertUnsignedBytesToHexString b      convertUnsignedBytesToHexString byte  is a method which converts an array of bytes in a string of hexadecimal characters   When I try to run these two blocks of code together  this is the output   48454c4c4f 202b0b78cc00ec11ec11ec11ec11ec11ec11ec   Clearly the text is being encoded  but the actual bytes of data are completely off  Any help would be appreciated here

User · Accepted Answer

So  for future reference for anybody who doesn t want to spend two days searching the internet to figure this out  when you encode byte arrays into QR Codes  you have to use the ISO-8859-1character set  not UTF-8

User · Answer

this is my working example Java code to encode QR code using ZXing with UTF-8 encoding  please note  you will need to change the path and utf8 data to your path and language characters   package com mypackage qr   import java io File  import java io IOException  import java io UnsupportedEncodingException  import java nio ByteBuffer  import java nio CharBuffer  import java nio charset CharacterCodingException  import java nio charset Charset  import java nio charset CharsetEncoder  import java util Hashtable   import com google zxing EncodeHintType  import com google zxing MultiFormatWriter  import com google zxing client j2se MatrixToImageWriter  import com google zxing common     public class CreateQR    public static void main String   args        Charset charset   Charset forName  UTF-8        CharsetEncoder encoder   charset newEncoder        byte   b   null      try              Convert a string to UTF-8 bytes in a ByteBuffer         ByteBuffer bbuf   encoder encode CharBuffer wrap  utf 8 characters - i used hebrew  but you should write some of your own language characters             b   bbuf array          catch  CharacterCodingException e            System out println e getMessage                String data      try           data   new String b   UTF-8               get a byte matrix for the data         BitMatrix matrix   null          int h   100          int w   100          com google zxing Writer writer   new MultiFormatWriter            try               Hashtable lt EncodeHintType  String gt  hints   new Hashtable lt EncodeHintType  String gt  2               hints put EncodeHintType CHARACTER SET   UTF-8                matrix   writer encode data              com google zxing BarcodeFormat QR CODE  w  h  hints             catch  com google zxing WriterException e                System out println e getMessage                           change this path to match yours  this is my mac home folder  you can use  c   qr png png if you are on windows                  String filePath     Users shaybc Desktop OutlookQR qr png png           File file   new File filePath           try               MatrixToImageWriter writeToFile matrix   PNG   file               System out println  printing to     file getAbsolutePath               catch  IOException e                System out println e getMessage                     catch  UnsupportedEncodingException e            System out println e getMessage

User · Answer

For what it s worth  my groovy spike seems to work with both UTF-8 and ISO-8859-1 character encodings  Not sure what will happen when a non zxing decoder tries to decode the UTF-8 encoded image though    probably varies depending on the device      ------------------------------------------------------------------------------------    Requires  groovy-1 7 6  jdk1 6 0 03    lib with zxing core-1 7 jar  javase-1 7 jar     Javadocs  http   zxing org w docs javadoc overview-summary html    Run with  groovy -cp    lib    zxing groovy    ------------------------------------------------------------------------------------  import com google zxing   import com google zxing common   import com google zxing client j2se    import java awt image BufferedImage import javax imageio ImageIO  def class zxing       def static main def args            def filename      qrcode png          def data    This is a test to see if I can encode and decode this data             def charset    UTF-8     ISO-8859-1           def hints   new Hashtable lt EncodeHintType  String gt    EncodeHintType CHARACTER SET   charset            writeQrCode filename  data  charset  hints  100  100           assert data    readQrCode filename  charset  hints             def static writeQrCode def filename  def data  def charset  def hints  def width  def height            BitMatrix matrix   new MultiFormatWriter   encode new String data getBytes charset   charset   BarcodeFormat QR CODE  width  height  hints          MatrixToImageWriter writeToFile matrix  filename substring filename lastIndexOf      1   new File filename              def static readQrCode def filename  def charset  def hints            BinaryBitmap binaryBitmap   new BinaryBitmap new HybridBinarizer new BufferedImageLuminanceSource ImageIO read new FileInputStream filename              Result result   new MultiFormatReader   decode binaryBitmap  hints           result getText

User · Answer

I tried using ISO-8859-1 as said in the first answer  All went ok on encoding  but when I tried to get the byte   using result string on decoding  all negative bytes became the character 63  question mark   The following code does not work      Encoding works great byte   contents   new byte   -1   QRCodeWriter codeWriter   new QRCodeWriter    BitMatrix bitMatrix   codeWriter encode new String contents  Charset forName  ISO-8859-1     BarcodeFormat QR CODE  w  h       Decodes like this fails LuminanceSource ls   new BufferedImageLuminanceSource encodedBufferedImage   Result result   new QRCodeReader   decode new BinaryBitmap  new HybridBinarizer ls     byte   resultBytes   result getText   getBytes Charset forName  ISO-8859-1        a byte   with byte 63 is given return resultBytes    It looks so strange because the API in a very old version  don t know exactly  had a method thar works well   Vector byteSegments   result getByteSegments      So I tried to search why this method was removed and realized that there is a way to get ByteSegments  through metadata  So my decode method looks like      Decodes like this works perfectly LuminanceSource ls   new BufferedImageLuminanceSource encodedBufferedImage   Result result   new QRCodeReader   decode new BinaryBitmap  new HybridBinarizer ls     Vector byteSegments    Vector  result getResultMetadata   get ResultMetadataType BYTE SEGMENTS     int i   0  int tam   0  for  Object o   byteSegments        byte   bs    byte   o      tam    bs length    byte   resultBytes   new byte tam   i   0  for  Object o   byteSegments        byte   bs    byte   o      for  byte b   bs            resultBytes i      b          return resultBytes

User · Answer

Maybe worth looking at QRGen  which is built on top of ZXing and supports UTF-8 with this kind of syntax      if using special characters don t forget to supply the encoding VCard johnSpecial   new VCard  J  hn D e                            setAdress            Str    t 1  1234 D  est  wn    QRCode from johnSpecial  withCharset  UTF-8   file

User · Answer

If you really need to encode UTF-8  you can try prepending the unicode byte order mark   I have no idea how widespread the support for this method is  but ZXing at least appears to support it  http   code google com p zxing issues detail id 103  I ve been reading up on QR Mode recently  and I think I ve seen the same practice mentioned elsewhere  but I ve not the foggiest where

[java] QR Code encoding and decoding using zxing

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