private static String getMessage(int code) {
		switch (code) {
		case ValidateSignatureError:
			return "签名验证错误";
		case ParseXmlError:
			return "xml解析失败";
		case ComputeSignatureError:
			return "sha加密生成签名失败";
		case IllegalAesKey:
			return "SymmetricKey非法";
		case ValidateAppidError:
			return "appid校验失败";
		case EncryptAESError:
			return "aes加密失败";
		case DecryptAESError:
			return "aes解密失败";
		case IllegalBuffer:
			return "解密后得到的buffer非法";
//		case EncodeBase64Error:
//			return "base64加密错误";
//		case DecodeBase64Error:
//			return "base64解密错误";
//		case GenReturnXmlError:
//			return "xml生成失败";
		default:
			return null; // cannot be
		}
	}