问浏览Javascript生成的网页

EN

public MainWindow()
        {
            InitializeComponent();

            var cookieJar = new CookieContainer();
            var handler = new HttpClientHandler
            {
                CookieContainer = cookieJar,
                UseCookies = true,
                UseDefaultCredentials = false
            };

            client = new HttpClient(handler)
            {
                BaseAddress = new Uri("https://servizi.ivass.it/RuirPubblica/Search.faces")
            };
        }

        private async Task TryHttp()
        {
            // Access the search page
            var response = await client.GetAsync(client.BaseAddress);

            var responseString = await response.Content.ReadAsStringAsync();

            // Perform the search
            var values = new Dictionary<string, string>
            {
                { "FormSearch", "FormSearch" },
                { "FormSearch:j_id_jsp_558348152_13", "PG" },
                { "FormSearch:j_id_jsp_558348152_16", "custom" },
                { "FormSearch:SecE", "on" },
                { "FormSearch:matricola", "" },
                { "FormSearch:ragioneSociale", "" },
                { "FormSearch:provincia", "NA" },
                { "FormSearch:SearchButton", "Ricerca" },
                { "javax.faces.ViewState", "j_id1:j_id5" },
            };

            var content = new FormUrlEncodedContent(values);

            response = await client.PostAsync(client.BaseAddress, content);

            // Here I'm getting a web page showing the error "Warning: Session expired"
            responseString = await response.Content.ReadAsStringAsync();
        }

        private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
        {
            TryHttp();
        }