今天獻上一個將時間戳加密成一個21位大寫英文字母串的java程式碼，並附上解密程式碼，思路很簡單，僅供娛樂

private Map<Character, String> codeMap; 
private String englishChars;
private ArrayList<Integer> changeIndex;
public SimpleDateFormat sdf;

/**
     * 加密時間
     * @author huzhen
     * @since 2017/7/12
     * @param date date()型別時間
     * */
 

    public String enTimeCode(Date enDate){
        String dataStr = null;
        try{
            dataStr = this.getSdf().format(enDate);
            String enStr = "";
            for(int i=0; i<dataStr.length(); i++){
                String transLetter = this.getCodeMap().get(dataStr.charAt(i));
                enStr = enStr + transLetter;
            }
            int
 
 changeCusor = 0;
            StringBuffer retStr = new StringBuffer(generateRandString(21));
            for(int i=0; i<retStr.length(); i++){
                if(this.getChangeIndex().contains(i)){
                    retStr.setCharAt(i, enStr.charAt(changeCusor));
                    changeCusor++;
                }
            }
            return
 
 retStr.toString();
        }catch(Exception e){
            //e.printStackTrace(); 
            System.out.println(e.getMessage());
            return "";
        }
    }

/**
     * 將加密後的亂碼解密
     * @author huzhen
     * @since 2017/7/12
     * @param date date()型別時間
     * */
    public Date deTimeCode(String enStr){
        String dateStr = "";
        try{
            String toDecodeStr = "";
            for(int i=0; i<enStr.length(); i++){
                if(this.getChangeIndex().contains(i)){
                    toDecodeStr = toDecodeStr + enStr.charAt(i);
                }               
            }
            for(int i=0; i<toDecodeStr.length(); i++){
                char deChar = valueGetKey(this.getCodeMap(), String.valueOf(toDecodeStr.charAt(i))).get(0);
                if(deChar != '\0'){
                    dateStr += deChar;
                }               
            }
        return this.getSdf().parse(dateStr);
        }catch(Exception e){
            //e.printStackTrace(); 
            System.out.println(enStr + "不符合規則！");
            return null;
        }
    }


private Map<Character, String> getCodeMap() {
        if(codeMap == null){
            codeMap = new HashMap<Character, String>();
            codeMap.put('0', "I");
            codeMap.put('1', "L");
            codeMap.put('2', "O");
            codeMap.put('3', "V");
            codeMap.put('4', "E");
            codeMap.put('5', "M");
            codeMap.put('6', "Y");
            codeMap.put('7', "D");
            codeMap.put('8', "N");
            codeMap.put('9', "S");
        }
        return codeMap;
    }

    private static ArrayList<Character> valueGetKey(Map<Character, String> map, String value) {
        Set<Entry<Character, String>> set = map.entrySet();
        ArrayList<Character> arr = new ArrayList<Character>();
        Iterator<Entry<Character, String>> it = set.iterator();
        while(it.hasNext()) {
             Map.Entry<Character, String> entry = (Map.Entry<Character, String>)it.next();
             if(entry.getValue().equals(value)) {
                   char s = (char)entry.getKey();
                   arr.add(s);
             }
        }
        return arr;
    }


    private String getEnglishChars() {
        if(englishChars == null){
            englishChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        }
        return englishChars;
    }

    private SimpleDateFormat getSdf() {
        if(sdf == null){
            sdf = new SimpleDateFormat("yyyyMMdd");
        }
        return sdf;
    }

    public ArrayList<Integer> getChangeIndex() {
        if(changeIndex == null){
            changeIndex = new ArrayList<Integer>();
            changeIndex.add(1);
            changeIndex.add(6);
            changeIndex.add(9);
            changeIndex.add(13);
            changeIndex.add(14);
            changeIndex.add(17);
            changeIndex.add(19);
            changeIndex.add(20);
        }
        return changeIndex;
    }

/**
     * 隨機生成指定位數的大寫英文字母串
     * @author huzhen
     * @since 2017/7/12
     * @param 
     * */
    private String generateRandString(int bits){
        String retStr = "";
        for(int i=0; i<bits; i++){
            retStr = retStr + this.getEnglishChars().charAt((int)(Math.random() * 26));
        }
        return retStr;
    }