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MVC 自定义AuthorizeAttribute实现权限管理

在上一节中提到可以使用AuthorizeAttribute进行权限管理：

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        [Authorize]
        public ActionResult TestAuthorize()
        {
            return View();
        }
 
        [Authorize(Users="test1,test2")]
        public ActionResult TestAuthorize()
        {
            return View();
        }
 
        [Authorize(Roles="Admin")]
        public ActionResult TestAuthorize()
        {
            return View();
        }

但是通常情况下，网站的权限并不是固定不变的，当新增角色或者角色改变时，只能修改每个Action对应的特性，当项目较大时工作量可想而知。幸运的是我们可以重写AuthorizeAttribute达到自定义的权限管理。新建一个CustomAuthorizeAttribute类，使这个类继承于AuthorizeAttribute。打开AuthorizeAttribute查看下方法说明，我们只需要重写AuthorizeCore和OnAuthorization就能达到我们的目的。

 

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// Summary:
        //     When overridden, provides an entry point for custom authorization checks.
        //
        // Parameters:
        //   httpContext:
        //     The HTTP context, which encapsulates all HTTP-specific information about
        //     an individual HTTP request.
        //
        // Returns:
        //     true if the user is authorized; otherwise, false.
        //
        // Exceptions:
        //   System.ArgumentNullException:
        //     The httpContext parameter is null.
        protected virtual bool AuthorizeCore(HttpContextBase httpContext);
 
 
//
        // Summary:
        //     Called when a process requests authorization.
        //
        // Parameters:
        //   filterContext:
        //     The filter context, which encapsulates information for using System.Web.Mvc.AuthorizeAttribute.
        //
        // Exceptions:
        //   System.ArgumentNullException:
        //     The filterContext parameter is null.
        public virtual void OnAuthorization(AuthorizationContext filterContext);

 

 

在CustomAuthorizeAttribute中重载AuthorizeCore方法，它的处理逻辑如下：首先判断当前账户是否被认证，如果没有，则返回false；然后获取当前账户的类型，并跟给定的类型进行比较，如果类型相同，则返回true，否则返回false。一般网站中权限管理都会使用权限树，然后将角色的权限保存至数据库或者文件中，本例中我们使用XML文件保存每个Action的角色，这样在用户请求Action时，由XML文件获取Action对应的权限，然后检测账户是否有相应的权限。CustomAuthorizeAttribute类的代码如下：

 

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public class CustomAuthorizeAttribute : System.Web.Mvc.AuthorizeAttribute
    {
        public new string[] Roles { get; set; }
        protected override bool AuthorizeCore(HttpContextBase httpContext)
        {
            if (httpContext == null) {
                throw new ArgumentNullException("HttpContext");
            }
            if (!httpContext.User.Identity.IsAuthenticated) {
                return false;
            }
            if (Roles == null) {
                return true;
            }
            if (Roles.Length == 0)
            {
                return true;
            }
            if (Roles.Any(httpContext.User.IsInRole))
            {
                return true;
            }
            return false;
        }
 
        public override void OnAuthorization(System.Web.Mvc.AuthorizationContext filterContext)
        {
            string controllerName = filterContext.ActionDescriptor.ControllerDescriptor.ControllerName;
            string actionName = filterContext.ActionDescriptor.ActionName;
            string roles = GetRoles.GetActionRoles(actionName, controllerName);
            if (!string.IsNullOrWhiteSpace(roles)) {
                this.Roles = roles.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);
            }
            base.OnAuthorization(filterContext);
        }
    }

 

当用户请求一个Action时，会调用OnAuthorization方法，该方法中GetRoles.GetActionRoles(actionName, controllerName);根据Controller和Action去查找当前Action需要具有的角色类型，获得Action的Roles以后，在AuthorizeCore中与用户的角色进行比对Roles.Any(httpContext.User.IsInRole)，如果没有相应权限则返回false，程序就会自动跳转到登录页面。

 

GetRoles为XML解析类，代码如下：

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   public class GetRoles
    {
      
        public static string GetActionRoles(string action, string controller) {
            XElement rootElement = XElement.Load(HttpContext.Current.Server.MapPath("/")+"ActionRoles.xml");
            XElement controllerElement = findElementByAttribute(rootElement, "Controller", controller);
            if (controllerElement != null)
            {
                XElement actionElement = findElementByAttribute(controllerElement, "Action", action);
                if (actionElement != null)
                {
                    return actionElement.Value;
                }
            }
            return "";
        }
 
        public static XElement findElementByAttribute(XElement xElement,string tagName, string attribute)
        {
            return xElement.Elements(tagName).FirstOrDefault(x => x.Attribute("name").Value.Equals(attribute,StringComparison.OrdinalIgnoreCase));
        }
    }

 

相应的权限XMl文件：

 

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<?xml version="1.0" encoding="utf-8" ?>
<Roles>
    <Controller name="Home">
        <Action name="Index"></Action>
        <Action name="About">Manager,Admin</Action>
        <Action name="Contact">Admin</Action>
    </Controller>
</Roles>

 

当需求发生变化时，只需要修改XML文件即可

使用时，只需要在FilterConfig中注册该filter

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filters.Add(new CustomAuthorizeAttribute());

 

当然这只是一个简单的例子，实际应用中会复杂许多，还可能要实现在即的MemberShipProvider和RoleProvider

from:http://www.cnblogs.com/jyan/archive/2012/07/24/2606646.html

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