c#通用登录模块，简单好用，一贴见效

// 举个例子：一个网站有用户系统、商家系统、网站后台3个系统
//可以分3个userType, user ,shop , system
//网站后台一般都有角色，如admin,employee
//那么网站的角色就有 user,shop,admin,employee,但是admin和employee在一个客户端是不能同时登陆的，所以他们是同一类用户（system）

使用方法：

1、添加一个类LoginUser.cs 代码如下：

代码：

namespace MVCCommonAuth
{
#region 功能说明
// 举个例子：一个网站有用户系统、商家系统、网站后台3个系统
//可以分3个userType, user ,shop , system
//网站后台一般都有角色，如admin,employee
//那么网站的角色就有 user,shop,admin,employee,但是admin和employee在一个客户端是不能同时登陆的，所以他们是同一类用户（system）
#endregion

public enum UserType
{
User,
Shop,
System
}

[Serializable]
public class LoginUser
{
private static string DESKEY = DateTime.Now.ToString("1234MMdd");
public int ID { get; set; }
public string UserName { get; set; }
public string Roles { get; set; }
public DateTime Expires { get; set; }

public readonly static string CookieNamePrefix = "authcookie";

public void Login(string userType, string domain = null, string path = null)
{
var keyName = CookieNamePrefix + userType;
var json = JsonConvert.SerializeObject(this);
var value = EncryptString(json, DESKEY);

HttpCookie cookie = new HttpCookie(keyName, value);
cookie.Expires = Expires;
if (!string.IsNullOrWhiteSpace(domain))
{
cookie.Domain = domain;
}
if (path != null)
{
cookie.Path = path;
}
HttpContext.Current.Items[keyName] = this;
HttpContext.Current.Response.Cookies.Add(cookie);
}

/// <summary>
/// 从cookie读取用户信息
/// </summary>
/// <param name="cookieName"></param>
private static LoginUser BuildUser(string keyName)
{
var cookie = HttpContext.Current.Request.Cookies[keyName];
if (cookie != null && !string.IsNullOrEmpty(cookie.Value))
{
try
{
var json = DecryptString(cookie.Value, DESKEY);
var loginuser = JsonConvert.DeserializeObject<LoginUser>(json);
if (loginuser != null)
{
if (loginuser.Expires >= DateTime.Now)
{
return loginuser;
}
}
}
catch
{
//do nothing
}
}
return null;
}

public static LoginUser GetUser(string userType)
{
var keyName = CookieNamePrefix + userType;
if (!HttpContext.Current.Items.Contains(keyName))
{
var user = BuildUser(keyName);
HttpContext.Current.Items[keyName] = user;
return user;
}
else
{
return HttpContext.Current.Items[keyName] as LoginUser;
}
}

public static int GetUserID(string userType)
{
var user = GetUser(userType);
if (user != null)
return user.ID;
return 0;
}

/// <summary>
/// 退出cookie登录
/// </summary>
public static void Logout(string userType)
{
var keyName = CookieNamePrefix + userType;

HttpCookie cookie = new HttpCookie(keyName, string.Empty);
cookie.Expires = DateTime.Now.AddMonths(-1);
HttpContext.Current.Response.Cookies.Add(cookie);
}

#region 字符串加密

/// <summary>
/// 利用DES加密算法加密字符串（可解密）
/// </summary>
/// <param name="plaintext">被加密的字符串</param>
/// <param name="key">密钥（只支持8个字节的密钥）</param>
/// <returns>加密后的字符串</returns>
private static string EncryptString(string plaintext, string key)
{
//访问数据加密标准(DES)算法的加密服务提供程序 (CSP) 版本的包装对象
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
des.Key = ASCIIEncoding.ASCII.GetBytes(key);　//建立加密对象的密钥和偏移量
des.IV = ASCIIEncoding.ASCII.GetBytes(key);　 //原文使用ASCIIEncoding.ASCII方法的GetBytes方法

byte[] inputByteArray = Encoding.Default.GetBytes(plaintext);//把字符串放到byte数组中

MemoryStream ms = new MemoryStream();//创建其支持存储区为内存的流　
//定义将数据流链接到加密转换的流
CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
//上面已经完成了把加密后的结果放到内存中去
StringBuilder ret = new StringBuilder();
foreach (byte b in ms.ToArray())
{
ret.AppendFormat("{0:X2}", b);
}
ret.ToString();
return ret.ToString();
}
/// <summary>
/// 利用DES解密算法解密密文（可解密）
/// </summary>
/// <param name="ciphertext">被解密的字符串</param>
/// <param name="key">密钥（只支持8个字节的密钥，同前面的加密密钥相同）</param>
/// <returns>返回被解密的字符串</returns>
private static string DecryptString(string ciphertext, string key)
{
try
{
DESCryptoServiceProvider des = new DESCryptoServiceProvider();

byte[] inputByteArray = new byte[ciphertext.Length / 2];
for (int x = 0; x < ciphertext.Length / 2; x++)
{
int i = (Convert.ToInt32(ciphertext.Substring(x * 2, 2), 16));
inputByteArray[x] = (byte)i;
}

des.Key = ASCIIEncoding.ASCII.GetBytes(key);　//建立加密对象的密钥和偏移量，此值重要，不能修改
des.IV = ASCIIEncoding.ASCII.GetBytes(key);
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);

cs.Write(inputByteArray, 0, inputByteArray.Length);

cs.FlushFinalBlock();

//建立StringBuild对象，createDecrypt使用的是流对象，必须把解密后的文本变成流对象
StringBuilder ret = new StringBuilder();

return System.Text.Encoding.Default.GetString(ms.ToArray());
}
catch (Exception)
{
return "error";
}
}

#endregion
}
}

2、登录处理过程，写入cookie：

[HttpPost]
public ActionResult Login(string username,string userpass)
{
if (username=="admin" && userpass=="admin")
{
LoginUser loginuser = new LoginUser();
loginuser.ID = 1;
loginuser.UserName = username;
loginuser.Roles = "Administrator";
loginuser.Expires = DateTime.Now.AddHours(2);

loginuser.Login("Administrator");

return Content("登录成功");
//return RedirectToAction("Index", "Home");
}

return RedirectToAction("Login");
}

3、判断用户是否登录：

//是否登录
if(LoginUser.GetUserID("Administrator") > 0)
{

}

// 用户ID
int userID=LoginUser.GetUserID("Administrator")

//获取用户名
string userName= LoginUser.GetUser("Administrator").UserName