Cookie拓展工具类

/// <summary>
/// 用于方便使用Cookie的扩展工具类
/// </summary>
public static class CookieExtension
{
    // 我们可以为一些使用频率高的类型写专门的【读取】方法

    /// <summary>
    /// 从一个Cookie中读取字符串值。
    /// </summary>
    /// <param name="cookie"></param>
    /// <returns></returns>
    public static string GetString(this HttpCookie cookie)
    {
        if( cookie == null )
            return null;

        return cookie.Value;
    }

    /// <summary>
    /// 从一个Cookie中读取 Int 值。
    /// </summary>
    /// <param name="cookie"></param>
    /// <param name="defaultVal"></param>
    /// <returns></returns>
    public static int ToInt(this HttpCookie cookie, int defaultVal)
    {
        if( cookie == null )
            return defaultVal;

        return cookie.Value.TryToInt(defaultVal);
    }

    /// <summary>
    /// 从一个Cookie中读取值并转成指定的类型
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="cookie"></param>
    /// <returns></returns>
    public static T ConverTo<T>(this HttpCookie cookie)
    {
        if( cookie == null )
            return default(T);

        return (T)Convert.ChangeType(cookie.Value, typeof(T));
    }

    /// <summary>
    /// 从一个Cookie中读取【JSON字符串】值并反序列化成一个对象，用于读取复杂对象
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="cookie"></param>
    /// <returns></returns>
    public static T FromJson<T>(this HttpCookie cookie)
    {
        if( cookie == null )
            return default(T);

        return cookie.Value.FromJson<T>();
    }


    /// <summary>
    /// 将一个对象写入到Cookie
    /// </summary>
    /// <param name="obj"></param>
    /// <param name="name"></param>
    /// <param name="expries"></param>
    public static void WriteCookie(this object obj, string name, DateTime? expries)
    {
        if( obj == null )
            throw new ArgumentNullException("obj");

        if( string.IsNullOrEmpty(name) )
            throw new ArgumentNullException("name");
        

        HttpCookie cookie = new HttpCookie(name, obj.ToString());

        if( expries.HasValue )
            cookie.Expires = expries.Value;

        HttpContext.Current.Response.Cookies.Add(cookie);
    }

    /// <summary>
    /// 删除指定的Cookie
    /// </summary>
    /// <param name="name"></param>
    public static void DeleteCookie(string name)
    {
        if( string.IsNullOrEmpty(name) )
            throw new ArgumentNullException("name");

        HttpCookie cookie = new HttpCookie(name);

        // 删除Cookie，其实就是设置一个【过期的日期】
        cookie.Expires = new DateTime(1900, 1, 1);
        HttpContext.Current.Response.Cookies.Add(cookie);
    }
}