webapi的几种过滤器

好久没有写博客了 今天就来聊聊asp.net webapi的过滤器们

过滤器主要有这么几种

AuthorizationFilterAttribute 权限验证

ActionFilterAttribute 日志 参数验证等

ExceptionFilterAttribute 异常处理捕获

我是如何使用这些过滤器的，最近在做项目中，这几种过滤器我都使用了，实现当别人调用接口的时候，首先验证权限，这个验证信息可以从Head里取也可以从Body里取，然后就是验证参数的有效性，参数需要后台验证，在实体里我都是定义了验证特性，拦截器正好根据这些特性统一做后台验证，所以我的后台数据验证统一在这一步就做完了，如果不符合直接抛出给客户端，然后还可以写日志，最后是异常的捕获，异常拦截器统一捕获异常，我在其它层就不要额外的做异常处理（事务方法除外，事务需要捕获异常回滚）

这些过滤器 作为全局过滤器直接配置好 不用每个api controller都去声明特性

    /// <summary>
    /// 接口的权限验证
    /// Token身份验证，只有合法的用户才可以访问  否则会转向到登录页面或者无权限提示页面
    /// </summary>
    public class AuthGlobalAttribute : AuthorizationFilterAttribute
    {
        public string Roles { get; set; }

        public string Users { get; set; }

        public override void OnAuthorization(HttpActionContext actionContext)
        {
            if (actionContext.ActionDescriptor.GetCustomAttributes<AllowAnonymousAttribute>().Any())
            {
                return;
            }
            string controllerName = actionContext.ActionDescriptor.ControllerDescriptor.ControllerName;
            string actionName = actionContext.ActionDescriptor.ActionName;
            HttpContextBase context = (HttpContextBase)actionContext.Request.Properties["MS_HttpContext"];//获取传统context
            HttpRequestBase request = context.Request;//定义传统request对象 
            if (request["Token"] == null && actionContext.Request.Headers.Authorization == null)
            {
                Result result = new Result { Flag = false, Message = "缺少Token身份信息", Code="203" };
                HttpResponseMessage httpResponseMessage = new HttpResponseMessage();
                httpResponseMessage.Content = new StringContent(JsonConvert.SerializeObject(result), Encoding.UTF8, "application/json");
                httpResponseMessage.StatusCode = HttpStatusCode.BadRequest;
                actionContext.Response = httpResponseMessage;
                return;
            }
            //参数带有Token
            string token = request["Token"];
            token = (token ?? actionContext.Request.Headers.Authorization.Parameter);

            //根据Token获取当前用户上下文
            if (UserCache.Cache.Get(token) != null)
            {
                HttpContext.Current.Items["User"] = UserCache.Cache.Get(token);
                //获取用户上下文后 根据Roles属性比对过滤器角色 如果没有权限向外面抛401
            }
            else
            {
                Result result = UserBLL.GetUserByToken(token);
                HttpResponseMessage httpResponseMessage = new HttpResponseMessage();
                httpResponseMessage.Content = new StringContent(JsonConvert.SerializeObject(result), Encoding.UTF8, "application/json");
                httpResponseMessage.StatusCode = HttpStatusCode.BadRequest;
                actionContext.Response = httpResponseMessage;
                //actionContext.Response = actionContext.Request.CreateErrorResponse(HttpStatusCode.Unauthorized, new HttpError("您无权限访问"));
                return;
            }
            base.OnAuthorization(actionContext);
        }


    }

    /// <summary>
    /// 全局参数验证实体
    /// </summary>
    public class ValidateGlobalAttribute : ActionFilterAttribute
    {
        /// <summary>
        /// 所有实体参数接口 全局验证
        /// </summary>
        /// <param name="filterContext"></param>
        public override void OnActionExecuting(HttpActionContext filterContext)
        {
            if (!filterContext.ModelState.IsValid)
            {
                ValidateResults vresult = new ValidateResults();
                foreach (string key in filterContext.ModelState.Keys)
                {
                    if (filterContext.ModelState[key].Errors.Count > 0)
                    {
                        vresult.ErrorResults.Add(new ValidateResult
                        {
                            IsValid = false,
                            MemberName = key,
                            ErrorMessage = filterContext.ModelState[key].Errors[0].ErrorMessage
                        });
                    }
                }
                Result<ValidateResults> result = new Result<ValidateResults> { Flag = false, Message = "数据验证失败", ResultObj = vresult,Code="208" };
                HttpResponseMessage httpResponseMessage = new HttpResponseMessage();
                httpResponseMessage.Content = new StringContent(JsonConvert.SerializeObject(result), Encoding.UTF8, "application/json");
                httpResponseMessage.StatusCode = HttpStatusCode.BadRequest;
                filterContext.Response = httpResponseMessage;
                return;
               // throw new HttpResponseException(oHttpResponseMessage);
            }
            base.OnActionExecuting(filterContext);
        }

    }

    /// <summary>
    /// 异常全局处理
    /// </summary>
    public class ExceptionGlobalAtrribute : ExceptionFilterAttribute
    {
        public override void OnException(HttpActionExecutedContext filterContext)
        {
            if (filterContext.Exception != null)
            {
                string controllerName = filterContext.ActionContext.ActionDescriptor.ControllerDescriptor.ControllerName;
                string actionName = filterContext.ActionContext.ActionDescriptor.ActionName;
                HttpContextBase context = (HttpContextBase)filterContext.Request.Properties["MS_HttpContext"];//获取传统context
                HttpRequestBase request = context.Request;//定义传统request对象 
                string token = string.Empty;
                if (request["Token"] != null || filterContext.Request.Headers.Authorization != null)
                {
                    token = request["Token"];
                    token = (token ?? filterContext.Request.Headers.Authorization.Parameter);
                }
                //获取当前用户上下文
                UserContext user = UserCache.Cache.Get(token);
                string description = filterContext.Exception.Message.ToString();
                //int autokey = DaoPack.Sys_UserLogDao.GetMax<int>(m => m.AutoKey) + 1;

                Sys_UserLog log = new Sys_UserLog
                {
                    //AutoKey = autokey,
                    ActionName = controllerName + "/" + actionName,
                    Description = description,
                    UserID = user == null ? null : (int?)user.UserID,
                    UserName = user == null ? null : user.UserName,
                    Url = request.RawUrl,
                    ClientIP=SysService.GetHostAddress()
                };
                DaoPack.Sys_UserLogDao.Insert(log);
            }
            HttpResponseMessage httpResponseMessage = new HttpResponseMessage();
            Result result = new Result { Flag = false, Message = "接口异常",Code="400" };
            httpResponseMessage.Content = new StringContent(JsonConvert.SerializeObject(result), Encoding.UTF8, "application/json");
            httpResponseMessage.StatusCode = HttpStatusCode.BadRequest;
            filterContext.Response = httpResponseMessage;
            return;
            //throw new HttpResponseException(oHttpResponseMessage);
            // base.OnException(filterContext);

        }
    }