MD5加密之加密字符串

 public static String encode(String str) {
         String encodeString = "";

         try {
             MessageDigest md = MessageDigest.getInstance("md5");
             // 用MD5加密后的字节数组
             byte[] digest = md.digest(str.getBytes());
             for (byte b : digest) {
                 // 将前面的ffffff去掉
                 int temp = b & 0x000000ff;
                 // 得到16进制
                 String s = Integer.toHexString(temp);
                 // 使每一位上都有两个数
                 if (s.length() == ) {
                     s = "" + s;
                 }

                 encodeString += s;
             }
         } catch (NoSuchAlgorithmException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         return encodeString;
     }