public String buildAsHex(BuilderMode builderMode) {
        byte[] ret = build(builderMode);
        if (Validator.isEmpty(ret)) {
            return null;
        }
        return DatatypeConverter.printHexBinary(ret);
    }
public String buildAsHex ( BuilderMode builderMode ) { byte [ ] ret = build ( builderMode ) ; if ( Validator . isEmpty ( ret ) ) { return null ; } return DatatypeConverter . printHexBinary ( ret ) ; }
完成HMAC认证消息的构建,并获得16进制编码表示的签名摘要值.

@param builderMode
构建模式的枚举
@return HMAC的16进制编码表示的签名摘要值字符串.若构建失败，则返回<code>null</code>
@author zhd
@since 1.0.0