在客户端创建一个username的cookies,其值为gjy,有效期为1天.
方法1:
Response.Cookies["username"].Value="zxf";
Response.Cookies["username"].Expires=DateTime.Now.AddDays(1);

方法2:
System.Web.HttpCookie newcookie=new HttpCookie("username");
newcookie.Value="gjy";
newcookie.Expires=DateTime.Now.AddDays(1);
Response.AppendCookie(newcookie);

创建带有子键的cookies:
System.Web.HttpCookie newcookie=new HttpCookie("user");
newcookie.Values["username"]="zxf";
newcookie.Values["password"]="111";
newcookie.Expires=DateTime.Now.AddDays(1);
Response.AppendCookie(newcookie);

cookies的读取:

无子键读取:
if(Request.Cookies["username"]!=null)
{
Response.Write(Server.HtmlEncode(Request.Cookies["username"].Value));
}

有子键读取:
if(Request.Cookies["user"]!=null)
{
Response.Write(Server.HtmlEncode(Request.Cookies["user"]["username"].Value));
Response.Write(Server.HtmlEncode(Request.Cookies["user"]["password"].Value));

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public class Cookie
{
/// <summary>
/// Cookies赋值
/// </summary>
/// <param name="strName">主键</param>
/// <param name="strValue">键值</param>
/// <param name="strDay">有效天数</param>
/// <returns></returns>
public bool setCookie(string strName, string strValue, int strDay)
{
try
{
HttpCookie Cookie = new HttpCookie(strName);
//Cookie.Domain = ".xxx.com";//当要跨域名访问的时候,给cookie指定域名即可,格式为.xxx.com
Cookie.Expires = DateTime.Now.AddDays(strDay);
Cookie.Value = strValue;
System.Web.HttpContext.Current.Response.Cookies.Add(Cookie);
return true;
}
catch
{
return false;
}
}

    /// <summary>
/// 读取Cookies
/// </summary>
/// <param name="strName">主键</param>
/// <returns></returns>

public string getCookie(string strName)
{
HttpCookie Cookie = System.Web.HttpContext.Current.Request.Cookies[strName];
if (Cookie != null)
{
return Cookie.Value.ToString();
}
else
{
return null;
}
}

    /// <summary>
/// 删除Cookies
/// </summary>
/// <param name="strName">主键</param>
/// <returns></returns>
public bool delCookie(string strName)
{
try
{
HttpCookie Cookie = new HttpCookie(strName);
//Cookie.Domain = ".xxx.com";//当要跨域名访问的时候,给cookie指定域名即可,格式为.xxx.com
Cookie.Expires = DateTime.Now.AddDays(-1);
System.Web.HttpContext.Current.Response.Cookies.Add(Cookie);
return true;
}
catch
{
return false;
}
}
}

示例：
Cookie Cookie = new Cookie();
Cookie.setCookie("name", "aaa",1);//赋值
Cookie.getCookie("name");//取值
Cookie.delCookie("name");//删除
注意:当Cookie存中文出现乱码,则在存放时给中文编码,如Cookie.setCookie("name", Server.UrlEncode("aaa"),1),读取时解码即可

另外：只要不给cookie设置过期时间,cookie在浏览器关闭的时候自动失效

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public class Cookie
{
/// <summary>
/// Cookies赋值
/// </summary>
/// <param name="strName">主键</param>
/// <param name="strValue">键值</param>
/// <param name="strDay">有效天数</param>
/// <returns></returns>
public bool setCookie(string strName, string strValue, int strDay)
{
try
{
HttpCookie Cookie = new HttpCookie(strName);
//Cookie.Domain = ".xxx.com";//当要跨域名访问的时候,给cookie指定域名即可,格式为.xxx.com
Cookie.Expires = DateTime.Now.AddDays(strDay);
Cookie.Value = strValue;
System.Web.HttpContext.Current.Response.Cookies.Add(Cookie);
return true;
}
catch
{
return false;
}
}

    /// <summary>
/// 读取Cookies
/// </summary>
/// <param name="strName">主键</param>
/// <returns></returns>

public string getCookie(string strName)
{
HttpCookie Cookie = System.Web.HttpContext.Current.Request.Cookies[strName];
if (Cookie != null)
{
return Cookie.Value.ToString();
}
else
{
return null;
}
}

    /// <summary>
/// 删除Cookies
/// </summary>
/// <param name="strName">主键</param>
/// <returns></returns>
public bool delCookie(string strName)
{
try
{
HttpCookie Cookie = new HttpCookie(strName);
//Cookie.Domain = ".xxx.com";//当要跨域名访问的时候,给cookie指定域名即可,格式为.xxx.com
Cookie.Expires = DateTime.Now.AddDays(-1);
System.Web.HttpContext.Current.Response.Cookies.Add(Cookie);
return true;
}
catch
{
return false;
}
}
}

示例：
Cookie Cookie = new Cookie();
Cookie.setCookie("name", "aaa",1);//赋值
Cookie.getCookie("name");//取值
Cookie.delCookie("name");//删除
注意:当Cookie存中文出现乱码,则在存放时给中文编码,如Cookie.setCookie("name", Server.UrlEncode("aaa"),1),读取时解码即可

另外：只要不给cookie设置过期时间,cookie在浏览器关闭的时候自动失效