如何在 If 条件下使用 C# 中的任务继续

Question

我已经在我的 .NET 应用程序中实现了 wcf 客户端。我的问题是如何确保在 Task> 完成后调用 if 条件？

  private List<MarketingCampaign> _GetAllCampaignTypeList()
    {
        List<MarketingCampaign> _MarketingCampaignList = null;

        Task<List<MarketingCampaignTypeData>> _MarketingCampaignTypeDataList = _MarketingCampaignTypeClientObject.GetAllCampaignTypes();

        ??? // how can I use continue with or Task.wait all in following if condition

        if(_MarketingCampaignTypeDataList!=null)
        {
           // code
        }

        return _MarketingCampaignList;
    }

上面的代码调用了下面的类

  public async Task<List<App.Client.Proxies.MarketingCampaignTypeServiceRef.MarketingCampaignTypeData>> GetAllCampaignTypes()
    {

        var task  = Task<List<App.Client.Proxies.MarketingCampaignTypeServiceRef.MarketingCampaignTypeData>>.Factory.StartNew(() => {
                                            return _MarketingCampaignTypeClient.GetAllCampaignTypes();
                                      });

        return await task.ConfigureAwait(false);

    }

Answer 1

我相信你需要这样的东西：

async Task<List<MarketingCampaign>> GetAllCampaignTypeList()
{
    List<MarketingCampaign> campaignList = null;

    List<MarketingCampaignTypeData> campaignTypeList = await _MarketingCampaignTypeClientObject.GetAllCampaignTypes();

    if(campaignTypeList != null)
    {
       // do whatever you need to convert campaignTypeList to campaignList
    }

    return campaignList;
}

另外，GetAllCampaignTypes 方法中不需要await，只需返回任务即可。我建议你不要在没有正当理由的情况下使用Task.Factory.StartNew。改用Task.Run：http://blog.stephencleary.com/2013/08/startnew-is-dangerous.html