使用 Android 的 Zxing 条码阅读器定义字符串大小

Question

I'm trying to set the string's length using a barcode reader. My problem is: I'm trying to create a MAC address barcode reader, encoded as barcode from some computer devices. So, every MAC Address has 12 digits and the barcode must read only 12 digits' strings in order to behave correctly. My code so far:

private void initiateScan(){
        IntentIntegrator integrator = IntentIntegrator.forSupportFragment(this);
        integrator.addExtra("PROMPT_MESSAGE","Put the Mac address at the center");
        integrator.setDesiredBarcodeFormats(IntentIntegrator.ONE_D_CODE_TYPES);
        integrator.initiateScan();
}

onActivityResult:

  @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
        if(result != null) {
            Context context = view.getContext();
            if(result.getContents() == null) {
                Log.d("MainActivity", "Cancelled scan");
                Toast.makeText(context, "Cancelled", Toast.LENGTH_SHORT).show();
            } else {
                Log.d("MainActivity", "Scanned");
                String content = result.getContents();
                Log.d(TAG,"scanned:: "+content);
                if(content.length() == UtilConstants.MAC_ADDRESS_SIZE){
                    if(field!=null)
                        field.setText(content);
                }else{
                    // invalid string size, reopen reader
                    Toast.makeText(getContext(),"Invalid code",Toast.LENGTH_SHORT).show();
                    initiateScan();
                }
            }
        } else {
            // This is important, otherwise the result will not be passed to the fragment
            super.onActivityResult(requestCode, resultCode, data);
        }
    }

Answer 1

I don't think this is possible yet because the general aim for barcode is to encode and decode but another way you can achieve this is to use a particular barcode format to generate and the same time scan your barcode. Barcodes come with their specific capacity ie how much content it can store or how much content can be encoded so consider using the EAN/UPC barcodes this type of barcodes stores maximum 13.

Answer 2

Representing a MAC address with 12 digits means that the characters used in each digit will be hexadecimal numbers 0-9 and AF(af).

In that case, all of 1D product code, ITF, Codabar, RSS14 cannot be used.
Code128 and RSS14_Expanded are not good uses because the data contents to be used are mainly determined.

If you use it within the support range of Zxing, it will be 1D Industrial Code 39, Code 93, and 2D barcode QR Code, DataMatrix, MaxiCode, Aztec, PDF 417.
zxing/zxing

There is ALLOWED_LENGTHS in DecodeHintType parameter of Zxing decodeRaw,decode API, so please give it a try.
Class Code39Reader
Class Code93Reader
Class QRCodeReader

Enum DecodeHintType
ALLOWED_LENGTHS

public static final DecodeHintType ALLOWED_LENGTHS
Allowed lengths of encoded data -- reject anything else. Maps to an int[].

There are other options that affect the reading format and notification format, so please try it.

However, there seems to be no function to limit the character code to hexadecimal characters, so even if the number of digits to be read can be specified, it is necessary to check the character code range after that.