package util;
import java.util.Random;
public class CharacterUtils {
public static String getRandomString(int length){
String str="abcdefABCDEF0123456789";
Random random = new Random();
StringBuffer sb = new StringBuffer();
for(int i = 0 ; i < length; ++i){
int number = random.nextInt(22);//[0,62)
sb.append(str.charAt(number));
}
return sb.toString();
}
public static void main(String[] args){
System.out.println(getRandomString(4));
}
}