java  随机码

package Rong;
import java.util.Random;

public class RandomStringUtils {
 private final static String numberTable ="0123456789";
 private final static String upperTable ="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 private final static String lowerTable =upperTable.toLowerCase();
 private final static String letterTable =upperTable + lowerTable;
 private final static String allTable =numberTable + letterTable;

 public enum StringType {
  NUMBER, LETTER, UPPER, LOWER, ALL
 }
 public static String random(int length,StringType type) {
  if (length < 0) {
   return "";
  }
  StringBuffer result = new StringBuffer();

  while (length-- > 0) {
   switch (type) {
   case NUMBER:
   result.append(numberTable.charAt(new Random().nextInt(10)));
    break;
   case LETTER:
   result.append(letterTable.charAt(new Random().nextInt(52)));
    break;
   case UPPER:
   result.append(upperTable.charAt(new Random().nextInt(26)));
    break;
   case LOWER:
   result.append(lowerTable.charAt(new Random().nextInt(26)));
    break;
   case ALL:
   result.append(allTable.charAt(new Random().nextInt(62)));
    break;
   default:
   result.append(numberTable.charAt(new Random().nextInt(10)));
   }
  }
  return result.toString();
 }

 public static void main(String[] args) {
  System.out.println(RandomStringUtils.random(6,StringType.NUMBER));//输出6位随机码(数字)
  System.out.println(RandomStringUtils.random(6,StringType.UPPER));//输出6位随机码(大写字母)
  System.out.println(RandomStringUtils.random(6,StringType.LOWER));//输出6位随机码(小写字母)
  System.out.println(RandomStringUtils.random(6,StringType.LETTER));//输出6位随机码(大小写字母)
  System.out.println(RandomStringUtils.random(6,StringType.ALL));//输出6位随机码(数字+大小写字母)
 }
}