c# - GetStringAsync 方法调用挂起 UI 并且永远不会完成

Question

我正在尝试使用 GetStringAsync 方法访问我的 url，但调用挂起并且永远不会结束。当我在浏览器中检查它时它工作完美但不知何故在我的代码中它永远不会结束。我的代码:

public bool Login(string url,string userName, string password)
    {
        try
        {
            Task<LoginResponse> response = GetLoginData(url, userName, password);
            if(response.Result.UserInfo.UserId > 0){
                IsAuthenticated = true;
            }
            return IsAuthenticated;
        }
        catch (ArgumentException argex)
        {
            ErrorMessage = argex.Message;
            IsAuthenticated = false;
            return IsAuthenticated;
        }
    }

    public async Task<LoginResponse> GetLoginData(string url, string userName, string password)
    {
        try{
            var param = new AuthenticationParam();
            param.UserName = userName;
            param.Password = password;

            var response = await LoginValidate(url, param);

            response = response.Replace("\"", string.Empty);
            response = response.Replace("\\", "\"");

            LoginResponse list = JsonConvert.DeserializeObject<LoginResponse>(
                response, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore });

            return list;
        }
        catch(Exception e){
            System.Diagnostics.Debug.WriteLine(e);
            return new LoginResponse();
        }
    }

    private static async Task<string> LoginValidate(string url, AuthenticationParam param){
        try
        {
            string result = "";
            using (var client = new HttpClient())
            {
                var json_data = string.Empty;
                json_data = JsonConvert.SerializeObject(param);
                var byteArray = Encoding.UTF8.GetBytes(json_data);
                var base64 = Convert.ToBase64String(byteArray);
                url = $"{url}{base64}";
                result = await client.GetStringAsync(url);
                return result;
            }
        }
        catch (Exception ex)
        {
            return "Error: " + ex.Message;
        }
    }

它卡在行 result = await client.GetStringAsync(url);

Answer 1

if(response.Result.UserInfo.UserId > 0){ -> .Result 是一个阻塞调用，可能会导致死锁。在调用链中一直使用 await。

public async Task<bool> Login(string url,string userName, string password)
{
    try
    {
        var response = await GetLoginData(url, userName, password);
        if(response.UserInfo.UserId > 0){
            IsAuthenticated = true;
        }
        return IsAuthenticated;
    }
    catch (ArgumentException argex)
    {
        ErrorMessage = argex.Message;
        IsAuthenticated = false;
        return IsAuthenticated;
    }
}

在调用堆栈中使用 var success = await Login(...);

请阅读 this关于如何创建此死锁的背景的优秀博文。