Question

我希望在没有任何条件的情况下强制缓存HttpRequest响应。但似乎有时它不起作用。可能是看标题，但我不想要它。例如，this url有时不会缓存。这是一个代码：

public static class HttpRequestHelper
{
    public const string ContentTypeForm = "application/x-www-form-urlencoded";

    public static HttpWebRequest CreateRequest(Uri uri)
    {
        HttpWebRequest request = WebRequest.CreateHttp(uri);
        request.Proxy = null;
        return request;
    }

    public enum CacheMode
    {
        None = 0,
        Hourly,
        Max,
    }

    public static string Request(Uri uri, CacheMode cache = CacheMode.None)
    {
        HttpWebRequest request = CreateRequest(uri);
        if (cache != CacheMode.None)
            request.CachePolicy = new HttpRequestCachePolicy(HttpCacheAgeControl.MaxStale,
                cache == CacheMode.Hourly ? TimeSpan.FromHours(1) : TimeSpan.FromDays(365));
        return GetContent(request);
    }

    public static HttpWebResponse GetResponse(HttpWebRequest request)
    {
        Contract.Requires(request != null);
        Debug.WriteLine("Request: " + request.RequestUri);
        var response = request.GetResponse() as HttpWebResponse;
        return response;
    }


    public static string GetContent(WebRequest request)
    {
        Contract.Requires(request != null);
        string data = "";
        using (var response = (HttpWebResponse)request.GetResponse())
        {
            Stream responseStream = response.GetResponseStream();
            if (responseStream == null) return data;
            using (var reader = new StreamReader(responseStream))
            {
                data = reader.ReadToEnd();
            }
        }
        return data;
    }
}

Answer 1

最可能的原因是服务器的响应指定了某种“不缓存”标头。即它可能是Pragma: no-cache - 所以尽管你付出了努力，项目也不会被缓存。

可能的解决方法是将结果自己缓存在内存中或磁盘上......

使HttpRequest缓存工作

1 个答案: