ResourceUtils.java

public class ResourceUtils {
    // example: ${date:DD.MM}
    private static final Pattern DATE_TIME_PLACEHOLDER_PATTERN =
            Pattern.compile("\\$\\{(?<value>date:[\\w.:\\-\\s/\\\\]+)}");

    // examples: ${number:N}
    private static final Pattern NUMBER_PLACEHOLDER_PATTERN =
            Pattern.compile("\\$\\{(?<value>number:[\\w.:\\-\\s/\\\\?]+)}");

    private static final Map<String, Formatter> FORMATTERS = Stream.of(
            new AbstractMap.SimpleEntry<>("date:DD.MM", new DateTimeFormatter("dd.MM")),
            new AbstractMap.SimpleEntry<>("date:DD.MM.YYYY", new DateTimeFormatter("dd.MM.yyyy")),
            new AbstractMap.SimpleEntry<>("date:DD.MM.YYYY HH:MM", new DateTimeFormatter("dd.MM.yyyy HH:mm")),

            new AbstractMap.SimpleEntry<>("number:N", new NumberFormatter("0")),
            new AbstractMap.SimpleEntry<>("number:N.00", new NumberFormatter("0.00")),
            new AbstractMap.SimpleEntry<>("number:N.??", new NumberFormatter("0.##"))
    ).collect(Collectors.toMap(AbstractMap.SimpleEntry::getKey, AbstractMap.SimpleEntry::getValue));

    private static final Formatter NULL_FORMATTER = arg -> "null";

    public static String formatString(String str, Object[] args) {
        if (StringUtils.isEmpty(str)) {
            return str;
        }
        List<Operation> operations = new ArrayList<>();
        collectOperations(operations, DATE_TIME_PLACEHOLDER_PATTERN, str);
        collectOperations(operations, NUMBER_PLACEHOLDER_PATTERN, str);
        if (operations.isEmpty()) {
            return str;
        } else if (operations.size() != args.length) {
            throw new IllegalArgumentException(String.format(
                    "Arguments count [%d] doesn't matches to placeholders count [%d]",
                    args.length, operations.size()));
        }
        operations.sort(Comparator.comparing(Operation::getRangeStart));

        StringBuilder sb = new StringBuilder();
        Operation lastOperation = null;
        for (int i = 0; i < operations.size(); i++) {
            Operation operation = operations.get(i);
            Object arg = args[i];

            Formatter formatter = arg == null ? NULL_FORMATTER : FORMATTERS.get(operation.getPattern());
            if (formatter == null) {
                throw new IllegalArgumentException(String.format(
                        "Unable to find appropriate formatter for pattern [%s]", operation.getPattern()));
            }

            String formattedValue;
            try {
                formattedValue = formatter.format(arg);
            } catch (RuntimeException e) {
                throw new IllegalArgumentException(String.format("Unable to format arg [%s] using pattern [%s]",
                        arg, operation.getPattern()), e);
            }

            int startIndex = lastOperation == null ? 0 : lastOperation.getRangeEnd() + 1;
            if (operation.getRangeStart() > startIndex) {
                sb.append(str.substring(startIndex, operation.getRangeStart()));
            }
            sb.append(formattedValue);
            lastOperation = operation;
        }
        if (lastOperation != null && lastOperation.getRangeEnd() < str.length() - 1) {
            sb.append(str.substring(lastOperation.getRangeEnd() + 1, str.length()));
        }
        return sb.toString();
    }

    private static void collectOperations(List<Operation> operations, Pattern pattern, String str) {
        Matcher matcher = pattern.matcher(str);
        while (matcher.find()) {
            operations.add(new Operation(matcher.start(), matcher.end() - 1, matcher.group("value")));
        }
    }

    private interface Formatter {
        String format(Object arg);
    }

    private static class DateTimeFormatter implements Formatter {
        private final java.time.format.DateTimeFormatter dateTimeFormatter;

        public DateTimeFormatter(String pattern) {
            this.dateTimeFormatter = java.time.format.DateTimeFormatter.ofPattern(pattern);
        }

        @Override
        public String format(Object arg) {
            if (!(arg instanceof TemporalAccessor)) {
                throw new IllegalArgumentException(
                        String.format("Argument [%s] can not be formatted as date-time value", arg));
            }
            return dateTimeFormatter.format((TemporalAccessor) arg);
        }
    }

    private static class NumberFormatter implements Formatter {
        private final DecimalFormat decimalFormat;

        public NumberFormatter(String pattern) {
            DecimalFormatSymbols dfs = DecimalFormatSymbols.getInstance();
            dfs.setDecimalSeparator('.');
            decimalFormat = new DecimalFormat(pattern);
            decimalFormat.setDecimalFormatSymbols(dfs);
        }

        @Override
        public synchronized String format(Object arg) {
            return decimalFormat.format(arg);
        }
    }

    private static class Operation {
        private final int rangeStart;
        private final int rangeEnd;
        private final String pattern;

        public Operation(int rangeStart, int rangeEnd, String pattern) {
            this.rangeStart = rangeStart;
            this.rangeEnd = rangeEnd;
            this.pattern = pattern;
        }

        public int getRangeStart() {
            return rangeStart;
        }

        public int getRangeEnd() {
            return rangeEnd;
        }

        public String getPattern() {
            return pattern;
        }
    }
}