asp.net cookie操作-添加cookie，添加键值，移除cookie，移除键值

public class Cookies
{
    /// <summary>
    /// 添加cookie
    /// </summary>
    /// <param name="cookieName"></param>
    /// <param name="value"></param>
    public static void Add(string cookieName, string value)
    {
        HttpCookie cookie = new HttpCookie(HttpUtility.UrlEncode(cookieName), HttpUtility.UrlEncode(value));
        HttpContext.Current.Response.AppendCookie(cookie);
    }

    /// <summary>
    /// 给指定的cookie的指定键添加值
    /// </summary>
    /// <param name="cookieName">cookie的名称</param>
    /// <param name="keyName">要添加的键</param>
    /// <param name="value">要添加的值</param>
    public static void Add(string cookieName, string keyName, string value)
    {
        HttpCookie cookie = HttpContext.Current.Request.Cookies[cookieName];
        //如果cookie=null则新建一个cookie
        if (cookie == null)
            cookie = new HttpCookie(HttpUtility.UrlEncode(cookieName));
        //如果该键不存在，则新建一个键值并赋值；否则直接赋值
        if (string.IsNullOrEmpty(cookie.Values[keyName]))
            cookie.Values.Add(keyName, HttpUtility.UrlEncode(value));
        else
            cookie.Values[keyName] = HttpUtility.UrlEncode(value);

        HttpContext.Current.Response.AppendCookie(cookie);
    }

    /// <summary>
    /// 读取Cookie
    /// </summary>
    /// <param name="key"></param>
    /// <returns></returns>
    public static string GetValue(string cookieName)
    {
        string value = HttpContext.Current.Request.Cookies[HttpUtility.UrlEncode(cookieName)].Value;
        return string.IsNullOrEmpty(value) ? string.Empty : HttpUtility.UrlDecode(value);
    }

    /// <summary>
    /// 读取指定Cookie里的指定键的值
    /// </summary>
    /// <param name="cookieName">cookie名称</param>
    /// <param name="keyName">cookie的键</param>
    /// <returns></returns>
    public static string GetValue(string cookieName, string keyName)
    {
        HttpCookie cookie = HttpContext.Current.Request.Cookies[HttpUtility.UrlEncode(cookieName)];
        if (cookie == null)
            return string.Empty;
        string value = cookie.Values[HttpUtility.UrlEncode(keyName)];
        return string.IsNullOrEmpty(value) ? string.Empty : HttpUtility.UrlDecode(value);
    }

    /// <summary>
    /// 获取指定cookie中所有的键
    /// </summary>
    /// <param name="cookieName"></param>
    /// <returns></returns>
    public static string[] GetValues(string cookieName)
    {
        if (HttpContext.Current.Request.Cookies[cookieName] == null)
            return new string[0];
        string[] keys = HttpContext.Current.Request.Cookies[cookieName].Values.AllKeys;
        for (int i = 0; i < keys.Length; i++)
        {
            keys[i] = HttpUtility.UrlDecode(keys[i]);
        }
        return keys;
    }

    /// <summary>
    /// 移除指定的Cookie
    /// </summary>
    /// <param name="cookieName"></param>
    public static void Remove(string cookieName)
    {
        HttpContext.Current.Response.Cookies.Remove(HttpUtility.UrlEncode(cookieName));
        HttpContext.Current.Response.Cookies[HttpUtility.UrlEncode(cookieName)].Expires = DateTime.Now.AddDays(-1);
    }
    /// <summary>
    /// 移除cookie中指定的键，若是最后一个键则移除这个cookie
    /// </summary>
    /// <param name="cookieName"></param>
    /// <param name="keyName"></param>
    public static void Remove(string cookieName, string keyName)
    {
        HttpCookie cookie = HttpContext.Current.Request.Cookies[cookieName];
        if (cookie != null)
        {
            if (cookie.Values.Count > 0)
            {
                if (cookie.Values.Count == 1)
                {
                    //若是最后一个键则移除这个cookie,否则会多出一个空值
                    cookie.Values.Remove(HttpUtility.UrlEncode(keyName));
                    cookie.Expires = DateTime.Now.AddDays(-1);
                }
                else
                {
                    cookie.Values.Remove(HttpUtility.UrlEncode(keyName));
                }
                HttpContext.Current.Response.Cookies.Add(cookie);
            }
        }
    }
}

首先要了解Cookie是存在客户端的。

添加cookie是向客户端添加cookie，所以要用(Response)HttpContext.Current.Response.AppendCookie(cookie);

获取cookie是获取客户端提交上来的cookie，所以要用(Request)HttpContext.Current.Request.Cookies[cookieName];

服务器端没有权限删除客户端上的文件，所以服务器端，不能删除cookie。但可以让浏览器删除，即让cookie过期。

关于cookie读取中文cookie时出现乱码：存储中文时要进行编码，读取中文时则进行解码，这样可以避免出现乱码。

cookie中存储数据的格式是以值键对的形式存储的：即 key1=value1&key2=value2;

所以

cookie.Values.Add(key1, value1);
和
cookie.Value=cookie.Value+"&key1=value1"
是等同的。但是后者在Request.Cookies[cookieName].Values.Count时则会变成1。
可能是加上新值之后编码不一所以count的时候变成了1