public static class HttpHelper
        {
            private static HttpClient _client;

            static HttpHelper()
            {
                _client = new HttpClient();
            }

            public static async Task<string> Get(string url)
            {
                try
                {
                    HttpResponseMessage response = await _client.GetAsync(url);
                    response.EnsureSuccessStatusCode();

                    return await response.Content.ReadAsStringAsync();
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"请求出错：{ex.Message}");
                    return null;
                }
            }

            public static async Task<string> Post(string url, string data, string contentType)
            {
                try
                {
                    HttpContent content = new StringContent(data, Encoding.UTF8, contentType);
                    HttpResponseMessage response = await _client.PostAsync(url, content);
                    response.EnsureSuccessStatusCode();
                    return await response.Content.ReadAsStringAsync();
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"请求出错：{ex.Message}");
                    return null;
                }
            }
        }