UUID生成

public class RandomUUID {

    /*
     * A-Z a-z 0-9
     */
    static String[] chars = new String[62];
    public static String[] createArray(){
        int j = 0;
        for (int i = 0; i < chars.length; i++) {
            if(i < 26){
                chars[i] = (char)('A' + j) + "";
                j++;
                if
 
(j>=26){
                    j=0;
            }

            }else if(i>=26 && i < 52){
                chars[i] = (char)('a' + j) + "";
                j++;
                if(j>=26)
                    j=0;
            }else{
                chars[i] = (char)('0' + j) + "";
                j++;
            }
        }
        return
 
 chars;
    }
    /**
     * 
     * @param uuid 是要傳遞進來的UUID
     * @param size 幾個驗證碼
     * @return
     */
    public static String getRandomUUID(String uuid,int size){
        //replace : 替換
        String uuid2 = uuid.replace("-", "");
        String validate = "";
        for (int i = 0; i < size; i++) {
            //substring ： 擷取
 

            String str = uuid2.substring(i*4, i*4+4);
            //根據16進位制轉換成一個整數
            int x = Integer.parseInt(str, 16);
            //從
            validate += chars[x % chars.length];
        }

        return validate;
    }


    public static void main(String[] args) {
        chars = createArray();
        String uuid = UUID.randomUUID().toString();
        //System.out.println(uuid);
        String s = "2a28d704917c40b08e6cfc6e37beaf9f";
        //System.out.println(s.substring(4, 8));//2a28 ,d704
        int x = Integer.parseInt("1a",16);
        //System.out.println(s.length() / 4);

        String validate = getRandomUUID(uuid, 5);
        System.out.println(validate);
    }