ASP.NET Web API 异常处理 HttpResponseException 以及Angularjs获取异常信息并提示

一、HttpResponseException

　　如果一个Web API控制器抛出一个未捕捉异常，默认地，大多数异常都会被转化成一个带有状态码“500 – 内部服务器错误”的HTTP响应。HttpResponseException（HTTP响应异常）类型会返回你在异常构造器中指定的任何HTTP状态码。例如，在以下方法中，如果id参数非法，会返回“404 — 未找到”。

public Product GetProduct(int id)
{
    Product item = repository.Get(id);
    if (item == null)
    { 
　　　　　//指定响应状态码
        throw new HttpResponseException(HttpStatusCode.NotFound);
    }
    return item;
}

　　为了对响应进行更多控制，你也可以构造整个响应消息HttpResponseMessage，并用HttpResponseException来包含它：

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"
        } 
　　　　　//包含一个HttpResponseMessage
        throw new HttpResponseException(resp);
    }
    return item;
}

二、Exception Filters

　　继承ExceptionFilterAttribute，重写OnException，最后都是抛出HttpResponseException，包含一个HttpResponseMessage，调用客户端可以获取该异常信息，进行相应处理。

 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; }
        }
    }

　　注册：

　　以下是全局注册，当然也可以在Controller或Action上标注

public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {

            // register exception handler.
            config.Filters.Add(new ExceptionHandlingAttribute());

        }
    }

三、客户端获取异常

　　通过AngularJs中AOP拦截响应实现

// 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 请求拦截
        request: function (config) {
            if (config.isWebApiRequest && !config.isPlugin) {
　　　　　　　　　　//地址上都自动附加上/api/v1
                config.url = (config.mkApiUrl || webApiHostUrl) + config.url;
                config.headers = config.headers || {};
　　　　　　　　 　//添加Authorization，用tokeentype  token格式来定义 ，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,响应拦截
        responseError: function (response) {
            $log.error(response); // Contains the data about the error.
            if (response.status === 401) {//状态码判断
                //window.location = '/logoff';
                Ares.logOff();
            } else if (response.data) {//返回内容判断
                if (response.data.name == 'TenantInactiveException') {

                    aresMaintainUtil.goToTenantInactivePage();
                }
　　　　　　　　　　//发布一个订阅，导致弹出一个对话框
                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 $q.reject(response);
        }
    };
}]);
//Aop拦截，对响应
webservices.config(['$httpProvider', function ($httpProvider) {
    $httpProvider.interceptors.push('apiInterceptor');

}]);

　　注册订阅：

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

    //弹出提示对话框
    var onApiErrorHappened = function (event, args) {
        if (args.data.name == 'MyOperationException'
                || args.data.name == 'CustomBusinessException') {
            customDialog.info('系统提示', args.data.message);
        }
    };