ASP.NET Web API 異常處理 HttpResponseException 以及Angularjs獲取異常信息並提示

一、HttpResponseException

　　如果一個Web API控制器拋出一個未捕捉異常，默認地，大多數異常都會被轉化成一個帶有狀態碼“500 – 內部服務器錯誤”的HTTP響應。HttpResponseException（HTTP響應異常）類型會返回你在異常構造器中指定的任何HTTP狀態碼。例如，在以下方法中，如果id參數非法，會返回“404 — 未找到”。

public Product GetProduct(int id) 
{ 
    Product item = repository.Get(id); 
    if (item == null) 
    { 
　　　　　//指定響應狀態碼 throw new HttpResponseException(HttpStatusCode.NotFound); 
    } 
    return item; 
}

　　為了對響應進行更多控制，你也可以構造整個響應消息HttpResponseMessage，並用HttpResponseException來包含它：

public Product GetProduct(int id) 
{ 
    Product item = repository.Get(id); 
    if (item == null) 
    { 
        var resp = new HttpResponseMessage(HttpStatusCode.NotFound) 
        { 
            Content = new StringContent(string.Format("No product with ID = {0}", id)), 
            ReasonPhrase = "Product ID Not Found" 
        } 
　　　　　//包含一個HttpResponseMessage throw new HttpResponseException(resp); 
    } 
    return item; 
}

二、Exception Filters

　　繼承ExceptionFilterAttribute，重寫OnException，最后都是拋出HttpResponseException，包含一個HttpResponseMessage，調用客戶端可以獲取該異常信息，進行相應處理。

 public class ExceptionHandlingAttribute : ExceptionFilterAttribute
    {
        public override void OnException(HttpActionExecutedContext context)
        {
            if (context.Exception != null && !(context.Exception is HttpResponseException))
            {
                MetricsConfig.MarkException(context.Exception);

                if (context.Exception is UnauthorizedAccessException)
                {
                    throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.Unauthorized));
                }

                var exceptionData = new ExceptionData
                {
                    Name = context.Exception.GetType().Name,
                    Message = context.Exception.GetBaseException().Message
                };

                if (context.Exception is ApplicationException)
                {
                    exceptionData.Message = context.Exception.Message;
                    var businessException = context.Exception as CustomBusinessException;
                    if (businessException != null)
                    {
                        exceptionData.Data = businessException.Data;
                    }
                }

                throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)
                {
                    Content = new ObjectContent<ExceptionData>(exceptionData, JsonFormatter),
                    ReasonPhrase = context.Exception.GetType().Name
                });

            }
        }

        private JsonMediaTypeFormatter _JsonFormatter;
        private JsonMediaTypeFormatter JsonFormatter
        {
            get
            {
                if (_JsonFormatter == null)
                {
                    _JsonFormatter = new JsonMediaTypeFormatter();
                    _JsonFormatter.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
                }
                return _JsonFormatter;
            }
        }

        // A simple class for generate response with json content.
        public class ExceptionData
        {
            public string Name { get; set; }
            public string Message { get; set; }
            public string Data { get; set; }
        }
    }

　　注冊：

　　以下是全局注冊，當然也可以在Controller或Action上標注

public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
           
            // register exception handler.
            config.Filters.Add(new ExceptionHandlingAttribute());

        }
    }

三、客戶端獲取異常

　　通過AngularJs中AOP攔截響應實現

// apiInterceptor is responsible to handle the aspect of each request and response.
webservices.factory('apiInterceptor',
['$q', '$log', '$injector', 'loginContext', 'eventAggregator', function ($q, $log, $injector, loginContext, eventAggregator) {
    'use strict';

    var apiToken = loginContext.apiToken;
    var tokenType = loginContext.tokenType;
    var webApiHostUrl = loginContext.apiHost + "/api/v1";

    return {
        //token save to services for further usage
        tokenType: tokenType,
        apiToken: apiToken,
        webApiHostUrl: webApiHostUrl,

        // On request success 請求攔截
        request: function (config) {
            if (config.isWebApiRequest && !config.isPlugin) {
　　　　　　　　　　//地址上都自動附加上/api/v1
                config.url = (config.mkApiUrl || webApiHostUrl) + config.url;
                config.headers = config.headers || {};
　　　　　　　　 　//添加Authorization，用tokeentype token格式來定義 ，如 ‘bearer sfsfsfsfsdf=sfsf+...’
                config.headers.Authorization = tokenType + ' ' + (config.mkToken || apiToken);
                var specificOfficeId = Ares.specificOfficeUtil.getOfficeId();
                if (specificOfficeId) {
                    config.headers["specific-office-id"] = specificOfficeId;
                }
            } else if (config.handleApiRequest) {
                config = config.handleApiRequest(config);
            }
            return config;
        },
        // On request failure
        requestError: function (rejection) {
            $log.error(rejection); // Contains the data about the error on the request.
            // Return the promise rejection.
            return $q.reject(rejection);
        },
        // On response failture,響應攔截
        responseError: function (response) {
            $log.error(response); // Contains the data about the error.
            if (response.status === 401) {//狀態碼判斷 //window.location = '/logoff';
                Ares.logOff();
            } else if (response.data) {//返回內容判斷 if (response.data.name == 'TenantInactiveException') {
                  
                    aresMaintainUtil.goToTenantInactivePage();
                }
　　　　　　　　　　//發布一個訂閱，導致彈出一個對話框
                eventAggregator.publish(eventAggregator.events.ApiErrorHappened, response, 'apiInterceptor');
            } else if (response.status === 0) {
                var isSaasApi = true;
                if (response.config && response.config.url.indexOf('//marketcenter') > -1) {
                    isSaasApi = false;
                }
                if (isSaasApi) {
                    aresMaintainUtil.ensureInMaintainMode().then(function (isInMaintainMode) {
                        if (isInMaintainMode) {
                            aresMaintainUtil.goToMaintainPage();
                        }
                    });
                }
            }
            // Return the promise rejection.
            return $q.reject(response);
        }
    };
}]);
//Aop攔截，對響應
webservices.config(['$httpProvider', function ($httpProvider) {
    $httpProvider.interceptors.push('apiInterceptor');

}]);

　　注冊訂閱：

var subscribeEvents = function () {
        eventAggregator.subscribe($scope, eventAggregator.events.ApiErrorHappened, onApiErrorHappened);
    };

    //彈出提示對話框
    var onApiErrorHappened = function (event, args) {
        if (args.data.name == 'MyOperationException'
                || args.data.name == 'CustomBusinessException') {
            customDialog.info('系統提示', args.data.message);
        }
    };