.netcore 写快递100的快递物流信息查询接口

快递100的物流信息查询接口，官方提供了一些demo;还好官方提供的代码是.netcore版本写的，不过写的有点low;根据官方提供的代码，我按照.netcore 的风格重构了代码；核心代码如下：

   /// <summary>
    /// 沐雪微淘快递100帮助类.
    /// </summary>
    public class KuaiDi100Helper
    {
        private ILogger _logger;
        private MuXueConfigHelper _configHelper;
        HttpClient _client;

        /// <summary>
        /// 快递100帮助类
        /// </summary>
        /// <param name="logger"></param>
        /// <param name="configHelper"></param>
        public KuaiDi100Helper(ILogger<KuaiDi100Helper> logger, HttpClient client, MuXueConfigHelper configHelper)
        {
            _configHelper = configHelper;
            _logger = logger;
            _client = client;
        }

        /// <summary>
        /// 实时快递查询接口
        /// </summary>
        /// <param name="tenant_id"></param>
        /// <param name="shop_code"></param>
        /// <param name="com">查询的快递公司的编码， 一律用小写字母</param>
        /// <param name="num">查询的快递单号， 单号的最大长度是32个字符</param>
        /// <param name="phone">收、寄件人的电话号码（手机和固定电话均可，只能填写一个，顺丰单号必填，其他快递公司选填。如座机号码有分机号，分机号无需上传。）</param>
        /// <returns></returns>
        public async Task<QueryTackResult> QueryTrack(long tenant_id, string shop_code,string com,string num,string phone="")
        {
            QueryTackResult result = new QueryTackResult();
            try
            {

                TenantConfig config = await _configHelper.GetTenantAllAsync(tenant_id, shop_code);

                QueryTrackParam queryTrackParam = new QueryTrackParam();
                if (com== "shunfeng")
                {
                      queryTrackParam = new QueryTrackParam()
                    {
                        com = com,
                        num = num,
                        phone = phone
                    };
                }
                else
                {
                      queryTrackParam = new QueryTrackParam()
                    {
                        com = com,
                        num = num,
                    };
                }

                QueryTrackReq query = new QueryTrackReq()
                {
                    customer = config.KuaiDi100CustomerID,
                    sign = SignUtils.GetMD5(queryTrackParam.ToString() + config.KuaiDi100Key + config.KuaiDi100CustomerID),
                    param = queryTrackParam
                };
                var requestParam = ObjectToDictionaryUtils.ObjectToMap(query);
                if (requestParam == null)
                {
                    return null;
                }

                 result = await HttpClientHelper.PostFormAsync<QueryTackResult>(_client, ApiInfoConstant.QUERY_URL, requestParam);

            }
            catch (Exception ex)
            {
                _logger.LogError(ex, $"快递100实时快递查询接口异常：{ex.Message}");
                return null;
            }
            return result;
        }

    }

上面的代码一眼看，就知道必须要使用依赖注入；我们看到 在构造函数里使用了HttpClient _client    这个东西；（因为要调用快递100的接口），

我们在startup里接着写：

 services.AddScoped<KuaiDi100Helper>();

如上代码应该是最常用的注册方法；结果报错，错误信息如下：

System.AggregateException:“Some services are not able to be constructed (Error while validating the service descriptor 'ServiceType: MuXue.WeTao.Mall.Core.kuaidi100.KuaiDi100Helper Lifetime: Scoped ImplementationType: MuXue.WeTao.Mall.Core.kuaidi100.KuaiDi100Helper': Unable to resolve service for type 'System.Net.Http.HttpClient' while attempting to activate 'MuXue.WeTao.Mall.Core.kuaidi100.KuaiDi100Helper'.)”

InvalidOperationException: Unable to resolve service for type 'System.Net.Http.HttpClient' while attempting to activate 'MuXue.WeTao.Mall.Core.kuaidi100.KuaiDi100Helper'.

根据错误信息看，应该是httpclient出了问题了；找了很久才找到解决方法，修改startup里的注册方法

services.AddHttpClient<KuaiDi100Helper>(); //这样注入

这样就没问题了。