调用 Web 服务的 C# DLL COM 在 Excel VB 中不起作用

Question

我目前有一个项目指南，试图将 C# DLL 作为 COM 用于 Excel 以及其他平台。目前，它调用 Web 服务并进行计算，例如从 Web 服务获取重力预测。除了当我需要使用使用 Web 服务的类方法时，一切都运行良好。我在 Excel 中收到一个错误，指出它无法与服务建立 SSL/TSL 连接，我似乎找不到解决方法。任何帮助都将不胜感激，因为我是一名终身开发人员，但将其放入 Excel 对我来说是全新的。以下是我在代码中的处理方式。

GravityResultObject.cs

public class GravityObjResult
{
    public string lat { get; set; }
    public string latDms { get; set; }
    public string lon { get; set; }
    public string lonDms { get; set; }
    public string eht { get; set; }

    public string predictedGravity { get; set; }
}

static void Main(string[] args)
{
}

public static async Task<string> TestGravApi(float lat, float lon, float eht)
{
    GravityObjResult gResult = new GravityObjResult();

    using (var httpClient = new HttpClient())
    {
        string url = String.Format("my-api-here-gp?lat={0}&lon={1}&eht={2}", lat, lon, eht);
        var json = await httpClient.GetStringAsync(url);

        if (json != null)
        {
                gResult = JsonConvert.DeserializeObject<GravityObjResult>(json);
                // Now parse with JSON.Net
                return gResult.predictedGravity;
            }
        }
        return String.Empty;
    }
}

GPredict.cs

public class GPredict
{
    public float Lon { get; set; }
    public float Lat { get; set; }
    public float Elip { get; set; }

    public float Grav { get; set; }

    public GPredict(float lon, float lat, float elip)
    {
        Lon = lon;
        Lat = lat;
        Elip = elip;
    }

    public GPredict()
    {
    }

    public float SetLON(float a)
    {
        Lon = a;
        return Lon;
    }

    public float SetLAT(float a)
    {
        Lat = a;
        return Lat;
    }

    public float SetELIP(float a)
    {
        Elip = a;
        return Elip;
    }

    public string GetG()
    {
        string gReturn = String.Empty;
        try
        {
            var task = WebRequestCall.TestGravApi(Lat, Lon, Elip);
            gReturn = float.Parse(task.Result).ToString();
        }
        catch (Exception e)
        {
            gReturn = e.ToString();
        }

        return gReturn;
    }
}

DynamicCalcWrapper.cs

public class DynamicCalcWrapper : DynamicObject
{
    Calculator calc;

    GPredict gPredict;

    public DynamicCalcWrapper()
    {
        calc = new Calculator();
        gPredict = new GPredict();
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        result = null;

        switch (binder.Name)
        {
            case "add":
                result = (Func<double, double, double>)((double a, double b) => calc.add(a, b));
                return true; 
            case "sub":
                result = (Func<double, double, double>)((double a, double b) => calc.sub(a, b));
                return true; 
            case "SetLON":
                result = (Func<float, float>)((float a) => gPredict.SetLON(a));
                return true;
            case "SetLAT":
                result = (Func<float, float>)((float a) => gPredict.SetLAT(a));
                return true;
            case "SetELIP":
                result = (Func<float, float>)((float a) => gPredict.SetELIP(a));
                return true;
            case "GetG":
                result = (Func<float, string>)((float a) => gPredict.GetG().ToString());
                return true;
        }
        return false; 
    }
}

在 Excel VB 中测试结果：

Sub T()
    Dim getG As New GPredict
    getG.Lon = 145#
    getG.Lat = 41.11
    getG.Elip = 33

    Dim result As String
    result = getG.getG()
    MsgBox result
End Sub

请注意，我有用于属性的常规 getter / setter，但也有设置它的辅助方法，因为我必须允许基于 Fortran 的代码使用它，并且对参数设置的长度等有一些限制.

Answer 1

我想指出，在将我的代码发布到示例中之前，我还尝试过首先直接指向上下文“https://”中的 url，直到抛出错误。通过在下面添加 ServicePointManager 的代码行，我发现我必须添加以下设置才能运行它：

public static async Task<string> TestGravApi(float lat, float lon, float eht)
    {
        GravityObjResult gResult = new GravityObjResult();

   ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls
   | SecurityProtocolType.Tls11
   | SecurityProtocolType.Tls12
   | SecurityProtocolType.Ssl3;

        using (var httpClient = new HttpClient())
        {
            string url = String.Format("https://{my-url-here}/api/gravd/gp?lat={0}&lon={1}&eht={2}", lat, lon, eht);
            var json = await httpClient.GetStringAsync(url);

            //sends from object to string json
            //string output = JsonConvert.SerializeObject(product);
            if (json != null)
            {
                gResult = JsonConvert.DeserializeObject<GravityObjResult>(json);
                // Now parse with JSON.Net
                return gResult.predictedGravity;
            }
        }

        return String.Empty;
    }