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 == 0) { return true; } if (Roles.Any(new Func<string, bool>(httpContext.User.IsInRole))) { return true; } httpContext.Response.StatusCode = 403; 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 == 403) { //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 = 500; filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;//禁用 IIS 自定义错误 }
看下弹出的错误效果