jodd-core/src/main/java/jodd/util/RandomString.java
public String random(int count, final char start, final char end) {
		if (count == 0) {
			return StringPool.EMPTY;
		}
		final char[] result = new char[count];
		final int len = end - start + 1;
		while (count-- > 0) {
			result[count] = (char) (rnd.nextInt(len) + start);
		}
		return new String(result);
	}
public String random(int count, final char start, final char end) {
		if (count == 0) {
			return StringPool.EMPTY;
		}
		final char[] result = new char[count];
		final int len = end - start + 1;
		while (count-- > 0) {
			result[count] = (char) (rnd.nextInt(len) + start);
		}
		return new String(result);
	}
Creates random string whose length is the number of characters specified.
Characters are chosen from the provided range.