Java tess4j仅用于识别数字和字母

我想将

tess4j

设置为仅识别数字和字母

Tesseract instance = new Tesseract();
instance.setDatapath("C:\\Users\\qyw\\Desktop\\tessdata");
String s = instance.doOCR(img);
System.out.println(s);

看

看

instance.setTessVariable("tessedit_char_whitelist", "0123456789abcdefghijklmnopqrstuvwxyz");