随机编码的生成

package com.**.util;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Set;

public class CouponCodeAutoGenerate {

    public static CouponCodeAutoGenerate generate =null;
    private final static String NUM_CHAR = "0123456789";
    
    private static int charLen = NUM_CHAR.length();  
    
    private CouponCodeAutoGenerate(){
        
    }
    public static CouponCodeAutoGenerate getInstance(){
        if(generate ==null){
            generate =new CouponCodeAutoGenerate();
        }
        return generate;
    }
    
    public Map<Long,String> autoGenerateCouponCode(Long memberId,List<Long> idList){
        Map<Long,String> map =new HashMap<Long, String>();
        
        
        
        StringBuilder  sb =null;
        StringBuilder sbr =null;
        
        int[] intRet = null;
        
        int insertIndex =0;
        for(Long id :idList){
            sb=new StringBuilder();
            //系统时间 5位
            sb.append(getRandomByCurrentTime(5));
            //memberId 5位左填充0
            sb.append(String.format("%05d",memberId));
            //类型 1位
            sb.append(id);
            // 5个随机字母
            sbr=new StringBuilder(getRandChar(5));
            intRet =getRetIndex(5,sb.length()+1);
            
            for(int i=0;i<sbr.length();i++){
                insertIndex =intRet[i]+i;
                sb.insert(insertIndex, sbr.charAt(i));
            }
            
            
            map.put(id, sb.toString());
        }
        
        
        
        return map;
    }
    
    public String getRandChar(int s){
        String val ="";
        for(int i=0 ;i <s ;i++){
            Random random = new Random();  
            int choice = random.nextInt(2) % 2 == 0 ? 65 : 97; //取得大写字母还是小写字母  
            val += (char) (choice + random.nextInt(26));
        }
        
        return val ;
    }
    
    
    public String getRandomByCurrentTime(int randomNumberDigit) {
         
         long seed = System.currentTimeMillis();// 获得系统时间，作为生成随机数的种子  
          StringBuffer sb = new StringBuffer();// 装载生成的随机数  
          Random random = new Random(seed);// 调用种子生成随机数  
          for (int i = 0; i < randomNumberDigit; i++) {  
             sb.append(NUM_CHAR.charAt(Math.abs(random.nextInt())% charLen));  
          }  
 
        return sb.toString();
 
    }
    //替换位置
    //从0-t中取s个不同数字
    public int[] getRetIndex(int s,int t) {
        // TODO Auto-generated method stub
        int[] intRet = new int[s]; 
        int intRd = 0; //存放随机数
        int count = 0; //记录生成的随机数个数
        int flag = 0; //是否已经生成过标志
        
        while(count<s){
             Random rdm = new Random();
             intRd = Math.abs(rdm.nextInt())% t;
             for(int i=0;i<count;i++){
                 if(intRet[i]==intRd){
                     flag = 1;
                     break;
                 }else{
                     flag = 0;
                 }
             }
             if(flag==0){
                 intRet[count] = intRd;
                 count++;
             }
            }
        return intRet;
    }
    
    public static void main(String[] args) {
        List<Long> typeList =new ArrayList<Long>();
        typeList.add(1L);
        typeList.add(2L);
        typeList.add(3L);
        Map<Long,String> code =CouponCodeAutoGenerate.getInstance().autoGenerateCouponCode(23l, typeList);
        
        Set<Map.Entry<Long,String>> it =code.entrySet();
        
        for (Map.Entry<Long,String> entry : it) {
            System.out.println(entry.getKey()+"---"+entry.getValue());
        }
        
    }
}