java生成唯一随即数

public class Caesar {
     private String table;
     private int seedA = 1103515245;
     private int seedB = 12345;
   
     public Caesar(String table, int seed) {
         this.table = chaos(table, seed, table.length());
     }
     public Caesar(String table) {
         this(table, 11);
     }
     public Caesar() {
         this(11);
     }
     public Caesar(int seed) {
         this("ABCDEFGHIJKLMNOPQRSTUVWXYZ", seed);
     }
     public char dict(int i, boolean reverse) {
         int s = table.length(), index = reverse ? s - i : i;
         return table.charAt(index);
     }
     public int dict(char c,  boolean reverse) {
         int s = table.length(), index = table.indexOf(c);
         return reverse ? s - index : index;
     }
     public int seed(int seed) {
         long temp = seed;
         return (int)((temp * seedA + seedB) & 0x7fffffffL);
     }
 
    public String chaos(String data, int seed, int cnt) {
         StringBuffer buf = new StringBuffer(data);
         char tmp; int a, b, r = data.length();
         for (int i = 0; i < cnt; i += 1) {
             seed = seed(seed); a = seed % r;
             seed = seed(seed); b = seed % r;
             tmp = buf.charAt(a);
             buf.setCharAt(a, buf.charAt(b));
             buf.setCharAt(b, tmp);
         }
         return buf.toString();
     }
 
    public String crypto(boolean reverse,
                          int key, String text) {
         String ret = null;
         StringBuilder buf = new StringBuilder();
         int m, s = table.length(), e = text.length();
 
        for(int i = 0; i < e; i += 1) {
             m = dict(text.charAt(i), reverse);
             if (m < 0) break;
             m = m + key + i;
             buf.append(dict(m % s, reverse));
         }
         if (buf.length() == e)
             ret = buf.toString();
         return ret;
     }
     public String encode(int key, String text) {
         return crypto(false, key, text);
       
     }
     public String decode(int key, String text) {
         return crypto(true , key, text);
     }
   
     public static void main(String[] args) {
         Caesar caesar = new Caesar();
         String data = caesar.encode(32, "APPLE");
         caesar.decode(32, data);
     }
 }

 

 

//*********************************

import java.util.Random;

public class Suiji {

 
 private Random random;
 private String table;
 public Suiji(){
  random = new Random();
  table="0123456789";
 }
 public String randomId(int id){
  String ret=null;
  String num=String.format("%03d", id);
  int key = random.nextInt(10);
  int seed=random.nextInt(100);
  Caesar caesar =  new Caesar(table,seed);
  num=caesar.encode(key, num);
  ret=num+String.format("%01d", key)+String.format("%02d", seed);
  return ret;
  
 }

 
 public static void main(String[] args) {

  Suiji suiji=new Suiji();
  //for(int i=0;i<30;i++){
   System.out.println(suiji.randomId(0));
  //}

 }

}