AJAX在C#中處理HTTP請求重定向的邏輯

在C#中，處理HTTP請求重定向通常是使用HttpClient類

using System;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;

namespace HttpRedirectExample
{
    class Program
    {
        static async Task Main(string[] args)
        {
            var url = "https://example.com/some-redirect-url";
            using (var httpClientHandler = new HttpClientHandler())
            {
                httpClientHandler.AllowAutoRedirect = false; // 禁用自動重定向

                using (var httpClient = new HttpClient(httpClientHandler))
                {
                    try
                    {
                        var response = await httpClient.GetAsync(url);

                        if (response.StatusCode == HttpStatusCode.Redirect || response.StatusCode == HttpStatusCode.MovedPermanently)
                        {
                            var redirectUrl = response.Headers.Location.ToString();
                            Console.WriteLine($"Redirect detected, new URL: {redirectUrl}");

                            // 手動處理重定向
                            var redirectResponse = await httpClient.GetAsync(redirectUrl);
                            if (redirectResponse.IsSuccessStatusCode)
                            {
                                var content = await redirectResponse.Content.ReadAsStringAsync();
                                Console.WriteLine($"Content from redirected URL: {content}");
                            }
                            else
                            {
                                Console.WriteLine($"Error: {redirectResponse.StatusCode}");
                            }
                        }
                        else if (response.IsSuccessStatusCode)
                        {
                            var content = await response.Content.ReadAsStringAsync();
                            Console.WriteLine($"Content: {content}");
                        }
                        else
                        {
                            Console.WriteLine($"Error: {response.StatusCode}");
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine($"Error: {ex.Message}");
                    }
                }
            }
        }
    }
}

在這個示例中，我們首先創建一個HttpClientHandler實例，將其AllowAutoRedirect屬性設置為false以禁用自動重定向。然后，我們使用HttpClient發送GET請求到指定的URL。如果響應狀態碼表示重定向（例如，HttpStatusCode.Redirect或HttpStatusCode.MovedPermanently），我們從響應頭中獲取新的URL，并手動發送另一個GET請求。最后，我們處理重定向后的響應并輸出結果。