Generate GS1-128 Barcode using Barcode4j library in Java Swing

Question

I have a string like (01)8638634367382(15)230316(3103)000998(10)45456465604 that I want to do it as barcode png using barcode4j lib in java. I use this code

  // Create the barcode bean
        Code128Bean barcode = new Code128Bean();

        // Configure the barcode generator
        final int dpi = 400;
        barcode.setModuleWidth(0.2);
        barcode.doQuietZone(false);

        int codeset = Code128Constants.CODESET_C;
        for (int i = 0; i < input.length(); i++) {
            char c = input.charAt(i);
            if (!Character.isDigit(c)) {
                codeset = Code128Constants.CODESET_B;
                break;
            }
        }
        barcode.setCodeset(codeset);
        // Generate the barcode bitmap
        BitmapCanvasProvider canvas = new BitmapCanvasProvider(dpi, BufferedImage.TYPE_BYTE_BINARY, false, 0);
        barcode.generateBarcode(canvas, input);
        try {
            canvas.finish();
        } catch (IOException e) {
            throw new RuntimeException("Error generating barcode", e);
        }

        // Encode the bitmap as a base64 string
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        try {
            ImageIO.write(canvas.getBufferedImage(), "png", outputStream);
        } catch (IOException e) {
            throw new RuntimeException("Error encoding barcode as PNG", e);
        }
        byte[] barcodeBytes = outputStream.toByteArray();
        String base64Barcode = Base64.getEncoder().encodeToString(barcodeBytes);
        
        return base64Barcode;

but the generated barcode isn't recognisable by any barcode scanner software. Also I encode the image to base64 string and when I want to represent in any part of my program I decode it and show the image. Any idea what's wrong with this?

I expect to produce a readable barcode in this format (01)8638634367382(15)230316(3103)000998(10)45456465604 and of course it must be scannable by any software.

Answer 1

The example that you have supplied is a GS1 Application Identifier element string in bracketed representation.

Unless the library does it for you, you will need to convert this to unbracketed representation with FNC1 in first position, suitable for encoding directly into a Code 128. (It is this process that differentiates GS1-128 from plain Code 128.)

The bracketed AI element string that you provided —(01)8638634367382(15)230316(3103)000998(10)45456465604 — does not decode correctly:

GTIN                   (01) 8638634367382    <-- Invalid. Too short.
BEST BEFORE or BEST BY (15) 230316
NET WEIGHT (kg)        (3103) 000998
BATCH/LOT              (10) 45456465604

Replacing the GTIN with one that is valid — (01)0101234567890128 — would allow you to represent the data in FNC1 in first syntax as "{FNC1}01012345678901281523031631030009981045456465604" which you will need to pass to the library as input in its expected format.

According to the barcode4j documentation the escape sequence particular to their software for encoding an FNC1 non-data character is a literal 0xF1 ASCII value:

Functions 1 to 4 may be used. They are encoded as ASCII characters 0xF1 (241), 0xF2 (242), 0xF3 (243) and 0xF4 (244) in the message.

More detail concerning the various representations of GS1 data is provided in this article.

GS1 provide the Barcode Syntax Resource which is a native library, with bindings for Java, that can process GS1 Application Identifier syntax data.

Answer 2

I had the same issue lastly and it seems to be not very clear in some point...what i have found after a long analysis is besides all you said previously you have to add some control characters if you want a valid gs1 code 128. For Example at the end of the string data you have to add a control character and eventually a stop character. All of them are printed by a char ascii number. By the way I didnt find a rutine or function in Java that passing a string (with the ais and the data) returned a string already parsed so i had to do one by my own (I "copied" one coded in vb so it was easy).