FantasticApiController(IAwesomeGenerator awesome,IBusinessRepository repository,IIceCreamFactory factory)
{
Awesome = awesome;
Repository = repository;
IceCream = factory.MakeIceCream();
DoSomeInitialization(); // this can throw an exception
}
通常,当WebAPI中的Controller操作抛出异常时,我可以通过一个csutom ExceptionFilterAttribute来处理它：
public class CustomErrorHandler
{
public override void OnException(HttpActionExecutedContext context)
{
// Critical error,this is real bad.
if (context.Exception is BubonicPlagueException)
{
Log.Error(context.Exception,"CLOSE EVERYTHING!");
Madagascar.ShutdownAllPorts();
}
// No big deal,just show something user friendly
throw new HttpResponseException(new HttpResponseMessage
{
Content = new StringContent("Hey something bad happened. " +
"Not closing the ports though"),StatusCode = HttpStatusCode.InternalServerError;
});
}
所以如果我有一个BoardPlane API方法抛出一个BubonicPlagueException,那么我的CustomerErrorHandler将关闭端口到马达加斯加,并按预期的方式将其记录为一个错误.在其他情况下,当它不是很严重时,我只显示一些用户友好的消息并返回500 InternalServerError.
但是在DoSomeInitialization引发异常的情况下,这绝对没有.如何处理WebAPI控制器构造函数中的异常？
解决方法
选项1& 2在github这里https://github.com/markyjones/StackOverflow/tree/master/ControllerExceptionHandling/src
方案1的工作相当不错,涉及使用DI容器(您可能已经使用了一个).我使用Ninject作为我的例子,并使用“Interceptor”Read More拦截并尝试/捕获对DefaultHttpControllerActivator的Create方法的调用.我至少知道AutoFac和Ninject可以做一些类似于以下的事情：
创建拦截器
我不知道你的马达加斯加和日志项目的生命周期是什么,但是他们可以很好地注入到你的拦截器中
public class ControllerCreationInterceptor : Ninject.Extensions.Interception.IInterceptor
{
private ILog _log;
private IMadagascar _madagascar;
public ControllerCreationInterceptor(ILog log,IMadagascar madagascar)
{
_log = log;
_madagascar = madagascar;
}
但是,请记住在你的问题中,Log和Madagascar是一种静态全局的例子
public class ControllerCreationInterceptor : Ninject.Extensions.Interception.IInterceptor
{
public void Intercept(Ninject.Extensions.Interception.IInvocation invocation)
{
try
{
invocation.Proceed();
}
catch(InvalidOperationException e)
{
if (e.InnerException is BubonicPlagueException)
{
Log.Error(e.InnerException,"CLOSE EVERYTHING!");
Madagascar.ShutdownAllPorts();
//DO SOMETHING WITH THE ORIGIONAL ERROR!
}
//DO SOMETHING WITH THE ORIGIONAL ERROR!
}
}
}
最终注册拦截器在全局asax或App_Start(NinjectWebCommon)
kernel.Bind<System.Web.Http.Dispatcher.IHttpControllerActivator>()
.To<System.Web.Http.Dispatcher.DefaultHttpControllerActivator>().Intercept().With<ControllerCreationInterceptor>();
选项2是实现自己的Controller Activator实现IHttpControllerActivator接口,并在Create方法中处理创建Controller的错误.您可以使用装饰器图案来包装DefaultHttpControllerActivator：
public class YourCustomControllerActivator : IHttpControllerActivator
{
private readonly IHttpControllerActivator _default = new DefaultHttpControllerActivator();
public YourCustomControllerActivator()
{
}
public System.Web.Http.Controllers.IHttpController Create(System.Net.Http.HttpRequestMessage request,System.Web.Http.Controllers.HttpControllerDescriptor controllerDescriptor,Type controllerType)
{
try
{
return _default.Create(request,controllerDescriptor,controllerType);
}
catch (InvalidOperationException e)
{
if (e.InnerException is BubonicPlagueException)
{
Log.Error(e.InnerException,"CLOSE EVERYTHING!");
Madagascar.ShutdownAllPorts();
//DO SOMETHING WITH THE ORIGIONAL ERROR!
}
//DO SOMETHING WITH THE ORIGIONAL ERROR!
return null;
}
}
}
一旦你有自己的定制激活器,默认的激活器可以是全局asax中的switched out：
GlobalConfiguration.Configuration.Services.Replace(typeof(IHttpControllerActivator),new YourCustomControllerActivator());
选项3当然,如果您在构造函数中的初始化不需要访问实际的Controllers方法,属性等,即假设可以从构造函数中删除…那么将初始化变为一个过滤器
public class MadagascarFilter : AbstractActionFilter
{
public override void OnActionExecuting(System.Web.Http.Controllers.HttpActionContext actionContext)
{
try{
DoSomeInitialization(); // this can throw an exception
}
catch(BubonicPlagueException e){
Log.Error(e,"CLOSE EVERYTHING!");
Madagascar.ShutdownAllPorts();
//DO SOMETHING WITH THE ERROR
}
base.OnActionExecuting(actionContext);
}
public override void OnActionExecuted(System.Web.Http.Filters.HttpActionExecutedContext actionExecutedContext)
{
base.OnActionExecuted(actionExecutedContext);
}
public override bool AllowMultiple
{
get { return false; }
}
}
