code: public static String getSHA1(String token, String timestamp, String nonce, String encrypt) throws AesException {
          try {
              String[] array = new String[]{token, timestamp, nonce, encrypt};
              StringBuilder sb = new StringBuilder();
              // 字符串排序
              Arrays.sort(array);
              for (int i = 0; i < 4; i++) {
                  sb.append(array[i]);
              }
              String str = sb.toString();
              // SHA1签名生成
              MessageDigest md = MessageDigest.getInstance("SHA-1");
              md.update(str.getBytes());
              byte[] digest = md.digest();
  
              StringBuilder hex = new StringBuilder();
              String shaHex;
              for (byte aDigest : digest) {
                  shaHex = Integer.toHexString(aDigest & 0xFF);
                  if (shaHex.length() < 2) {
                      hex.append(0);
                  }
                  hex.append(shaHex);
              }
              return hex.toString();
          } catch (Exception e) {
              throw new AesException(AesException.ComputeSignatureError);
          }
      }
docs: 用SHA1算法生成安全签名
  
  @param token     票据
  @param timestamp 时间戳
  @param nonce     随机字符串
  @param encrypt   密文
  @return 安全签名
  @throws AesException