不要试图给Password类型的TextBox赋值!
在asp.net中，不要试图给Password类型的TextBox控件赋值! 无论是在设计或是运行时，都不可以的。
猜测的原因是，password类型的TextBox控件从根本上，没有Text属性的Set方法，只有Get !!
同样，html中的Input控件，如果设置为ruanat="server"，password类型的Input控件也是一样。无论是在设计或是运行时，都不容许设置它的值。
解决办法:txtPassword.Attributes["value"] = "123";
前言
一般只要有会员、用户机制的网站或论坛在登录的时候都会有这么一个复选框--[记住我的名字 | 两周内不再登陆 | 在此计算机上保存我的信息]，说法较多，实现起来差不多，本文做了一个简单的例子并附带了一个C# Cookies帮助类 CookiesHelper.cs和实现代码片段，希望能对初学者有帮助: )
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1. 林信良 index.dat文件剖析 较深入分析cookies在index.dat中存入情况
2. MSDN -- ASP.NET Cookie 概述 很全面很详细的介绍了Cookies
正文
CookiesHelper.cs
using System.Collections.Generic;
using System.Text;
using System.Web;
namespace TLibrary.ObjectHelper
{
publicclass CookiesHelper
{
#region 获取Cookie
///<summary>
/// 获得Cookie的值
///</summary>
///<param name="cookieName"></param>
///<returns></returns>
publicstaticstring GetCookieValue(string cookieName)
{
return GetCookieValue(cookieName, null);
}
///<summary>
/// 获得Cookie的值
///</summary>
///<param name="cookieName"></param>
///<param name="key"></param>
///<returns></returns>
publicstaticstring GetCookieValue(string cookieName,string key)
{
HttpRequest request = HttpContext.Current.Request;
if (request !=null)
return GetCookieValue(request.Cookies[cookieName], key);
return"";
}
///<summary>
/// 获得Cookie的子键值
///</summary>
///<param name="cookie"></param>
///<param name="key"></param>
///<returns></returns>
publicstaticstring GetCookieValue(HttpCookie cookie, string key)
{
if (cookie !=null)
{
if (!string.IsNullOrEmpty(key) && cookie.HasKeys)
return cookie.Values[key];
else
return cookie.Value;
}
return"";
}
///<summary>
/// 获得Cookie
///</summary>
///<param name="cookieName"></param>
///<returns></returns>
publicstatic HttpCookie GetCookie(string cookieName)
{
HttpRequest request = HttpContext.Current.Request;
if (request !=null)
return request.Cookies[cookieName];
returnnull;
}
#endregion
#region 删除Cookie
///<summary>
/// 删除Cookie
///</summary>
///<param name="cookieName"></param>
publicstaticvoid RemoveCookie(string cookieName)
{
RemoveCookie(cookieName,null);
}
///<summary>
/// 删除Cookie的子键
///</summary>
///<param name="cookieName"></param>
///<param name="key"></param>
publicstaticvoid RemoveCookie(string cookieName,string key)
{
HttpResponse response = HttpContext.Current.Response;
if (response !=null)
{
HttpCookie cookie = response.Cookies[cookieName];
if (cookie !=null)
{
if (!string.IsNullOrEmpty(key) && cookie.HasKeys)
cookie.Values.Remove(key);
else
response.Cookies.Remove(cookieName);
}
}
}
#endregion
#region 设置/修改Cookie
///<summary>
/// 设置Cookie子键的值
///</summary>
///<param name="cookieName"></param>
///<param name="key"></param>
///<param name="value"></param>
publicstaticvoid SetCookie(string cookieName, string key, string value)
{
SetCookie(cookieName, key, value, null);
}
///<summary>
/// 设置Cookie值
///</summary>
///<param name="key"></param>
///<param name="value"></param>
publicstaticvoid SetCookie(string key, string value)
{
SetCookie(key, null, value, null);
}
///<summary>
/// 设置Cookie值和过期时间
///</summary>
///<param name="key"></param>
///<param name="value"></param>
///<param name="expires"></param>
publicstaticvoid SetCookie(string key, string value, DateTime expires)
{
SetCookie(key, null, value, expires);
}
///<summary>
/// 设置Cookie过期时间
///</summary>
///<param name="cookieName"></param>
///<param name="expires"></param>
publicstaticvoid SetCookie(string cookieName, DateTime expires)
{
SetCookie(cookieName, null, null, expires);
}
///<summary>
/// 设置Cookie
///</summary>
///<param name="cookieName"></param>
///<param name="key"></param>
///<param name="value"></param>
///<param name="expires"></param>
publicstaticvoid SetCookie(string cookieName, string key, string value, DateTime? expires)
{
HttpResponse response = HttpContext.Current.Response;
if (response !=null)
{
HttpCookie cookie = response.Cookies[cookieName];
if (cookie !=null)
{
if (!string.IsNullOrEmpty(key) && cookie.HasKeys)
cookie.Values.Set(key, value);
else
if (!string.IsNullOrEmpty(value))
cookie.Value = value;
if (expires !=null)
cookie.Expires = expires.Value;
response.SetCookie(cookie);
}
}
}
#endregion
#region 添加Cookie
///<summary>
/// 添加Cookie
///</summary>
///<param name="key"></param>
///<param name="value"></param>
publicstaticvoid AddCookie(string key, string value)
{
AddCookie(new HttpCookie(key, value));
}
///<summary>
/// 添加Cookie
///</summary>
///<param name="key"></param>
///<param name="value"></param>
///<param name="expires"></param>
publicstaticvoid AddCookie(string key, string value, DateTime expires)
{
HttpCookie cookie =new HttpCookie(key, value);
cookie.Expires = expires;
AddCookie(cookie);
}
///<summary>
/// 添加为Cookie.Values集合
///</summary>
///<param name="cookieName"></param>
///<param name="key"></param>
///<param name="value"></param>
publicstaticvoid AddCookie(string cookieName,string key, string value)
{
HttpCookie cookie =new HttpCookie(cookieName);
cookie.Values.Add(key, value);
AddCookie(cookie);
}
///<summary>
/// 添加为Cookie集合
///</summary>
///<param name="cookieName">Cookie名称</param>
///<param name="expires">过期时间</param>
publicstaticvoid AddCookie(string cookieName, DateTime expires)
{
HttpCookie cookie =new HttpCookie(cookieName);
cookie.Expires = expires;
AddCookie(cookie);
}
///<summary>
/// 添加为Cookie.Values集合
///</summary>
///<param name="cookieName"></param>
///<param name="key"></param>
///<param name="value"></param>
///<param name="expires"></param>
publicstaticvoid AddCookie(string cookieName, string key, string value, DateTime expires)
{
HttpCookie cookie =new HttpCookie(cookieName);
cookie.Expires = expires;
cookie.Values.Add(key, value);
AddCookie(cookie);
}
///<summary>
/// 添加Cookie
///</summary>
///<param name="cookie"></param>
publicstaticvoid AddCookie(HttpCookie cookie)
{
HttpResponse response = HttpContext.Current.Response;
if (response !=null)
{
//指定客户端脚本是否可以访问[默认为false]
cookie.HttpOnly =true;
//指定统一的Path，比便能通存通取
cookie.Path ="/";
//设置跨域,这样在其它二级域名下就都可以访问到了
//cookie.Domain = "chinesecoo.com";
response.AppendCookie(cookie);
}
}
#endregion
}
}
代码注意事项:
1. Cookies添加的时候注意一个Cookie可以添加多个子键
2. 假如你不显示的设置 HttpCookie.Expires 那么此 cookie 生命期即为浏览器进程--关闭浏览器则过期
3. 需要了解HttpCookie.Domain和HttpCookie.Path这两个属性，对于跨域和存储路径等高级应用有帮助
以下看实际调用代码
页面加载
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
HttpCookie Cookie = CookiesHelper.GetCookie("UserInfo");
if (Cookie != null)
{
this.txtUserName.Value = Cookie.Values["uName"];
}
}
}
代码说明：
1. this.txtUserName是界面上输入用户名的控件，换成自己的控件名称就行；
2. UserInfo为Cookie的名称，uName为Cookie的子键。
这段代码的功能是在页面加载的时候显示用户Cookie中记录的用户名，这里也可以做成连密码一起记录然后在这里显示，这样用户就可以直接点登录按钮了
登录验证
string uName = this.txtUserName.Value.Trim();
//验证用户名密码
if (IsLogin(uName, this.txtPass.Value.Trim()))
{
//记住我的名字
if (!string.IsNullOrEmpty(Request["remUsername"]))
{
HttpCookie Cookie = CookiesHelper.GetCookie("UserInfo");
if (Cookie == null)
{
Cookie = new HttpCookie("UserInfo");
Cookie.Values.Add("uName", uName);
//设置Cookie过期时间
Cookie.Expires = DateTime.Now.AddDays(365);
CookiesHelper.AddCookie(Cookie);
}
else if (!Cookie.Values["uName"].Equals(uName))
CookiesHelper.SetCookie("UserInfo", "uName", uName);
}
Response.Redirect("~/index.aspx");
}
代码说明：
1. this.txtUserName和this.txtPass是界面上输入用户名和密码的控件，换成自己的控件名称就行；
2. IsLogin方法是用来验证用户名和密码是否正确的，这里替换成自己的验证方法就行了。
3. Request["remUsername"]是获得界面上是否选中了[记住我的名称]复选框
这段代码的功能是在用户登录成功之后，如果选中了记住登录用户名就把用户名存入客户端的Cookie中，并设置过期时间为1年。
补充
1. 根据实际的经验，一般的情况下在本地调试不设置Domain属性，挂上服务器上配上域名之后就得指定Domain参数了，否则Cookies出不来的。（2008-11-24 10:32:00）