MicroCoder

/// <summary>
/// method for converting a UNIX timestamp to a regular
/// System.DateTime value (and also to the current local time)
/// </summary>
/// <param name="timestamp">value to be converted</param>
/// <returns>converted DateTime in string format</returns>
private static DateTime ConvertTimestamp(double timestamp)
{
    //create a new DateTime value based on the Unix Epoch
    DateTime converted = new DateTime(1970, 1, 1, 0, 0, 0, 0);

    //add the timestamp to the value
    DateTime newDateTime = converted.AddSeconds(timestamp);

    //return the value in string format
    return newDateTime.ToLocalTime();
}

/// <summary>
/// method for converting a System.DateTime value to a UNIX Timestamp
/// </summary>
/// <param name="value">date to convert</param>
/// <returns></returns>
private double ConvertToTimestamp(DateTime value)
{
    //create Timespan by subtracting the value provided from
    //the Unix Epoch
    TimeSpan span = (value - new DateTime(1970, 1, 1, 0, 0, 0, 0).ToLocalTime());

    //return the total seconds (which is a UNIX timestamp)
    return (double)span.TotalSeconds;
}

public static class TConverter
{
    public static T ChangeType<T>(object value)
    {
        return (T)ChangeType(typeof(T), value);
    }
    public static object ChangeType(Type t, object value)
    {
        TypeConverter tc = TypeDescriptor.GetConverter(t);
        return tc.ConvertFrom(value);
    }
    public static void RegisterTypeConverter<T, TC>() where TC : TypeConverter
    {
        TypeDescriptor.AddAttributes(typeof(T), new TypeConverterAttribute(typeof(TC)));
    }
}

    public static bool IsCached(HttpContext context, TimeSpan cacheDuration)
    {
        var modifiedSince = context.Request.Headers["If-Modified-Since"];
        if (!string.IsNullOrEmpty(modifiedSince))
        {
            modifiedSince = Regex.Replace(modifiedSince, @";.*$", "");//ie6
        }
        DateTime modified;
        if (DateTime.TryParse(modifiedSince, out modified) && modified.Add(cacheDuration) > DateTime.Now)
        {
            context.Response.StatusCode = 304;
            context.Response.Status = "304 Not Modified";
            return true;
        }
        return false;
    }
    public static void SetCachedHeader(HttpContext context, TimeSpan cacheDuration)
    {
        FieldInfo maxAge = context.Response.Cache.GetType().GetField("_maxAge",
BindingFlags.Instance | BindingFlags.NonPublic);
        maxAge.SetValue(context.Response.Cache, cacheDuration);
        //context.Response.Cache.SetMaxAge(cacheDuration);
        context.Response.Cache.SetETag(string.Empty);
        context.Response.Cache.SetCacheability(HttpCacheability.Public);
        context.Response.Cache.SetLastModified(DateTime.Now);
        context.Response.Cache.SetExpires(DateTime.Now.Add(cacheDuration));
        context.Response.Cache.AppendCacheExtension(
                "must-revalidate, proxy-revalidate");
    }
    public static void Cached(HttpContext context)
    {
        Cached(context, TimeSpan.FromMinutes(10));
    }

    public static void Cached(HttpContext context, TimeSpan cacheDuration)
    {
        if (!IsCached(context, cacheDuration))
        {
            SetCachedHeader(context, cacheDuration);
        }
        else
        {
            context.Response.End();
        }

    }
    public static void GZIP(HttpContext context)
    {
        string acceptEncoding = context.Request.Headers["Accept-Encoding"];

        if (!String.IsNullOrEmpty(acceptEncoding))
        {
            acceptEncoding = acceptEncoding.ToString().ToUpperInvariant();
            //如果头部里有包含"GZIP”,"DEFLATE",表示你浏览器支持 GZIP,DEFLATE压缩
            if (acceptEncoding.Contains("GZIP"))
            {
                //向输出流头部添加压缩信息
                context.Response.AppendHeader("Content-encoding", "gzip");
                context.Response.Filter = new GZipStream(context.Response.Filter, CompressionMode.Compress);
            }
            else if (acceptEncoding.Contains("DEFLATE"))
            {
                //向输出流头部添加压缩信息
                context.Response.AppendHeader("Content-encoding", "deflate");
                context.Response.Filter = new DeflateStream(context.Response.Filter, CompressionMode.Compress);
            }
        }
    }