WebRequest 忽略缓存

publicstaticWebResponseGetResponseNoCache(Uri uri)
{
        // Set a default policy level for the "http:" and "https" schemes.
        HttpRequestCachePolicy policy =newHttpRequestCachePolicy(HttpRequestCacheLevel.Default);
        HttpWebRequest.DefaultCachePolicy= policy;
        // Create the request.
        WebRequest request =WebRequest.Create(uri);
        // Define a cache policy for this request only. 
        HttpRequestCachePolicy noCachePolicy =newHttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore);
        request.CachePolicy= noCachePolicy;
        WebResponse response = request.GetResponse();
        Console.WriteLine("IsFromCache? {0}", response.IsFromCache);            
        return response;
}