asp.net cookie操作-添加cookie，添加鍵值，移除cookie，移除鍵值

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>
	/// 給指定的cookie的指定鍵添加值
	/// </summary>
	/// <param name="cookieName">cookie的名稱</param>
	/// <param name="keyName">要添加的鍵</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則新建一個cookie
		if (cookie == null)
			cookie = new HttpCookie(HttpUtility.UrlEncode(cookieName));
		//如果該鍵不存在，則新建一個鍵值並賦值；否則直接賦值
		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>
	/// 讀取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>
	/// 讀取指定Cookie裏的指定鍵的值
	/// </summary>
	/// <param name="cookieName">cookie名稱</param>
	/// <param name="keyName">cookie的鍵</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>
	/// 獲取指定cookie中所有的鍵
	/// </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中指定的鍵，若是最後一個鍵則移除這個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)
				{
					//若是最後一個鍵則移除這個cookie,否則會多出一個空值
					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是存在客戶端的。

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

獲取cookie是獲取客戶端提交上來的cookie，所以要用(Request)HttpContext.Current.Request.Cookies[cookieName];

服務器端沒有權限刪除客戶端上的文件，所以服務器端，不能刪除cookie。但可以讓瀏覽器刪除，即讓cookie過期。

關於cookie讀取中文cookie時出現亂碼：存儲中文時要進行編碼，讀取中文時則進行解碼，這樣可以避免出現亂碼。

cookie中存儲數據的格式是以值鍵對的形式存儲的：即 key1=value1&key2=value2;

所以

cookie.Values.Add(key1, value1);
和
cookie.Value=cookie.Value+"&key1=value1"
是等同的。但是後者在Request.Cookies[cookieName].Values.Count時則會變成1。
可能是加上新值之後編碼不一所以count的時候變成了1