如果想要记录ajax的请求和输出信息、内部发生异常记录日志、需要登录认证、需要权限判断；那mvc的各种filter可以帮助你实现你想要的。Mvc框架支持5种不同类型的过滤器；我会按照执行顺序进行简单的demo,再简单的代码分享，万一对一个人有益，也是值的。
1.通过实现IAuthenticationFilter来进行登录认证，如果认证通过继续后续的权限授权等操作；如果认证没有通过跳转登录页面；代码如下：
public class MvcAuthenticationFilter : FilterAttribute, IAuthenticationFilter
{
/// <summary>
/// 是否需要认证
/// </summary>
public bool IsNeedAuthentication { get; set; } /// <summary>
/// 对请求进行身份验证
/// </summary>
/// <param name="filterContext"></param>
public void OnAuthentication(AuthenticationContext filterContext)
{
bool flag = filterContext.ActionDescriptor.IsDefined(typeof(AllowAnonymousAttribute), true) || filterContext.ActionDescriptor.ControllerDescriptor.IsDefined(typeof(AllowAnonymousAttribute), true);
if (flag)
{
return;
}
if (IsNeedAuthentication)
{
IPrincipal user;
if (this.IsAuthenticated(filterContext, out user))
{
filterContext.Principal = user;
}
else
{
this.UnauthenticatedRequest(filterContext);
}
}
} protected bool IsAuthenticated(AuthenticationContext filterContext, out IPrincipal user)
{
user = filterContext.HttpContext.User;
var cc = filterContext.Controller.ControllerContext.Controller as BaseController;
if (cc != null && cc.CurrentAdminInfo != null)
{
IIdentity identity = user.Identity;
user = new GenericPrincipal(identity, new[] { "root", "noroot" }); //这里根据实际情况获取用户的角色
return true;
}
return false;
} protected void UnauthenticatedRequest(AuthenticationContext filterContext)
{
string returnUrl = filterContext.HttpContext.Request.Url.AbsolutePath;
string redirectUrl = string.Format("?ReturnUrl={0}", returnUrl);
string loginUrl = FormsAuthentication.LoginUrl + redirectUrl;
filterContext.HttpContext.Response.Redirect(loginUrl, true);
}
public void OnAuthenticationChallenge(AuthenticationChallengeContext filterContext) { }
}
2.每个管理后台都少不了权限判断的需求；你可以使用[Authorize(Roles = "r1,r2")] 默认实现进行硬编码，对于用户的权限和角色经常变动的话，或者你需要灵活的处理就需要自定义Authorize，咱们先看下Authorize源代码实现你就会明白
他的实现原理，先判断是否有匿名访问标签，然后利用AuthorizeCore 授权检查，如果未授权利用HandleUnauthorizedRequest 放回401，跳转到登录页面；很明显授权不通过跳转登录页面不是太合适；另一种实现方式
自定义Authorize 代码如下：
public new string[] Roles { get; set; }
protected override bool AuthorizeCore(HttpContextBase httpContext)
{
//由原来指定的roles 替换成动态读取的。
//跟登录用户的roles进行比较。
if (httpContext == null)
{
throw new ArgumentNullException("httpContext");
}
if (!httpContext.User.Identity.IsAuthenticated)
{
return false;
}
if (Roles == null)
{
return true;
}
if (Roles.Length == )
{
return true;
}
if (Roles.Any(new Func<string, bool>(httpContext.User.IsInRole)))
{
return true;
}
httpContext.Response.StatusCode = ;
return false;
}
protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
{
filterContext.Result = new HttpUnauthorizedResult();
}
public override void OnAuthorization(AuthorizationContext filterContext)
{
bool flag = filterContext.ActionDescriptor.IsDefined(typeof(AllowAnonymousAttribute), true) || filterContext.ActionDescriptor.ControllerDescriptor.IsDefined(typeof(AllowAnonymousAttribute), true);
if (flag)
{
return;
}
string controllerName = filterContext.ActionDescriptor.ControllerDescriptor.ControllerName;
string actionName = filterContext.ActionDescriptor.ActionName;
string roles = string.Join(",", GetRoles(actionName, controllerName));
if (!string.IsNullOrWhiteSpace(roles))
{
this.Roles = roles.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);
}
base.OnAuthorization(filterContext);
if (filterContext.HttpContext.Response.StatusCode == )
{
//跳转未授权页面
filterContext.Result = new RedirectResult("/Other/Noright");
}
}3.动作过滤器记录一些ajax的输入输出数据，方便排查问题；代码有注释也比较简单直接贴代码了
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
if (filterContext.HttpContext.Request.IsAjaxRequest())
{
var httpContext = filterContext.HttpContext;
//输入参数
var req = new JavaScriptSerializer().Serialize(HttpContext.Current.Request.Form.AllKeys.ToDictionary(k => k, k => HttpContext.Current.Request.Form[k]));
var code = httpContext.Request.GetHashCode();
var controllerName = filterContext.RouteData.Values["controller"] as string;
var actionName = filterContext.RouteData.Values["action"] as string;
var postUrl = controllerName + "/" + actionName;
LogHelper.WriteDebug(
string.Format("RequestUrl:{0};HashCode:{1}</br>RequestParam{2}",
postUrl, code,
req));
}
} public override void OnActionExecuted(ActionExecutedContext filterContext)
{
if (filterContext.HttpContext.Request.IsAjaxRequest())
{
//输出参数
var jsonR = filterContext.Result as JsonResult;
var res = new JavaScriptSerializer().Serialize(jsonR);
LogHelper.WriteDebug(string.Format("OnActionExecuted---返回值:{0}", res));
} }
4.最后是发生异常的处理，mvc默认实现HandleErrorAttribute，但是也不够灵活，查看源代码
我们定义之后的代码
public override void OnException(ExceptionContext filterContext)
{
string errCode = "";
string errMsg = "";
//自定义错误
if (filterContext.Exception is ClException)
{
}
else
{
errMsg = "未知错误";
LogHelper.WriteError(filterContext.Exception.Message);
}
//如果是ajax请求
if (filterContext.HttpContext.Request.IsAjaxRequest())
{
var result = new ExceptionResponse
{
ErrMsg = errMsg,
};
filterContext.Result = new JsonResult()
{
Data = result
};
}//500服务器内部错误
else
{
filterContext.Result = new ViewResult() { ViewName = "/Views/Other/Seerro.cshtml" };
} filterContext.ExceptionHandled = true;//阻止golbal里的错误执行
filterContext.HttpContext.Response.Clear();
filterContext.HttpContext.Response.StatusCode = ;
filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;//禁用 IIS 自定义错误
}
看下弹出的错误效果