我们平常在程序里面为了捕获异常，会加上try-catch-finally代码，但是这样会使得程序代码看起来很庞大，在MVC中我们可以使用异常过滤器来捕获程序中的异常，如下图所示：
使用了异常过滤器以后，我们就不需要在Action方法里面写Try -Catch-Finally这样的异常处理代码了，而把这份工作交给HandleError去做，这个特性同样可以应用到Controller上面，也可以应用到Action方面上面。
注意：
使用异常过滤器的时候，customErrors配置节属性mode的值，必须为On。
演示示例：
1、Error控制器代码如下：
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Web; 5 using System.Web.Mvc; 6 using System.Data.SqlClient; 7 using System.IO; 8 ?9 namespace _3_异常过滤器.Controllers10 {11 ????public class ErrorController : Controller12 ????{13 ????????// GET: Error14 ????????[HandleError(ExceptionType =typeof(ArithmeticException),View ="Error")]15 ????????public ActionResult Index(int a,int b)16 ????????{17 ????????????int c = a / b;18 ????????????ViewData["Result"] = c;19 ????????????return View();20 ????????}21 22 ????????/// <summary>23 ????????/// 测试数据库异常24 ????????/// </summary>25 ????????/// <returns></returns>26 ????????[HandleError(ExceptionType = typeof(SqlException), View = "Error")]27 ????????public ActionResult DbError()28 ????????{29 ????????????// 错误的连接字符串30 ????????????SqlConnection conn = new SqlConnection(@"Initial Catalog=StudentSystem; Integrated Security=False;User Id=sa;Password=******;Data Source=127.0.0.1");31 ????????????conn.Open();32 ????????????// 返回Index视图33 ????????????return View("Index");34 ????????}35 36 ????????/// <summary>37 ????????/// IO异常38 ????????/// </summary>39 ????????/// <returns></returns>40 ????????[HandleError(ExceptionType = typeof(IOException), View = "Error")]41 ????????public ActionResult IOError()42 ????????{43 ????????????// 访问一个不存在的文件44 ????????????System.IO.File.Open(@"D:\error.txt",System.IO.FileMode.Open);45 ????????????// 返回Index视图46 ????????????return View("Index");47 ????????}48 ????}49 }2、路由配置如下：
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Web; 5 using System.Web.Mvc; 6 using System.Web.Routing; 7 ?8 namespace _3_异常过滤器 9 {10 ????public class RouteConfig11 ????{12 ????????public static void RegisterRoutes(RouteCollection routes)13 ????????{14 ????????????routes.IgnoreRoute("{resource}.axd/{*pathInfo}");15 16 ????????????routes.MapRoute(17 ????????????????name: "Default",18 ????????????????url: "{controller}/{action}/{id}",19 ????????????????defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }20 ????????????);21 22 ????????????// 新增路由配置23 ????????????routes.MapRoute(24 ??????????????name: "Default2",25 ??????????????url: "{controller}/{action}/{a}/{b}",26 ??????????????defaults: new { controller = "Home", action = "Index", a=0,b=0 }27 ??????????);28 ????????}29 ????}30 }3、配置文件如下：
<system.web> ???<compilation debug="true" targetFramework="4.6.1" /> ???<httpRuntime targetFramework="4.6.1" /> ???<httpModules> ?????<add name="ApplicationInsightsWebTracking" type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web" /> ???</httpModules> ???<!--customErrors配置节mode的属性值必须为On--> ???<customErrors mode="On"> ????????</customErrors></system.web>
4、运行结果
URL：http://localhost:21868/error/index/8/4
结果：
URL：http://localhost:21868/error/index/8/0
结果：
URL：http://localhost:21868/error/DbError
结果：
URL：http://localhost:21868/error/IOError
结果：
在同一个控制器或Action方法上可以通过HandleError处理多个异常，通过Order属性决定捕获的先后顺序,但最上面的异常必须是下面异常的同类级别或子类。如下图所示：
上面的程序可以修改成如下的代码：
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Web; 5 using System.Web.Mvc; 6 using System.Data.SqlClient; 7 using System.IO; 8 ?9 namespace _3_异常过滤器.Controllers10 {11 ????[HandleError(Order =1, ExceptionType = typeof(SqlException), View = "Error")]12 ????[HandleError(Order =2, ExceptionType = typeof(IOException), View = "Error")]13 ????[HandleError(Order =3)] //不指定View，默认跳转到Share下面的Error视图14 ????public class ErrorController : Controller15 ????{16 ????????public ActionResult Index(int a,int b)17 ????????{18 ????????????int c = a / b;19 ????????????ViewData["Result"] = c;20 ????????????return View();21 ????????}22 23 ????????/// <summary>24 ????????/// 测试数据库异常25 ????????/// </summary>26 ????????/// <returns></returns>27 ????????public ActionResult DbError()28 ????????{29 ????????????// 错误的连接字符串30 ????????????SqlConnection conn = new SqlConnection(@"Initial Catalog=StudentSystem; Integrated Security=False;User Id=sa;Password=******;Data Source=127.0.0.1");31 ????????????conn.Open();32 ????????????// 返回Index视图33 ????????????return View("Index");34 ????????}35 36 ????????/// <summary>37 ????????/// IO异常38 ????????/// </summary>39 ????????/// <returns></returns>40 ????????public ActionResult IOError()41 ????????{42 ????????????// 访问一个不存在的文件43 ????????????System.IO.File.Open(@"D:\error.txt",System.IO.FileMode.Open);44 ????????????// 返回Index视图45 ????????????return View("Index");46 ????????}47 ????}48 }在上面的示例中，捕获异常的时候只是跳转到了Error视图，如果我们想获取异常的具体信息该怎么办呢？如下图所示：
查看MVC源码，可以发现HandleError返回的是HandleErrorInfo类型的model，利用该model可以获取异常的具体信息，修改Error视图页面如下：
@model HandleErrorInfo<!DOCTYPE html><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> ???<meta name="viewport" content="width=device-width" /> ???<title>错误</title> ???<style type="text/css"> ???????p{ ???????????color:red; ???????} ???</style></head><body> ???@*<hgroup> ???????<h1>错误。</h1> ???????<h2>处理你的请求时出错。</h2> ???</hgroup>*@ ???<p> ???????抛错控制器：<b>@Model.ControllerName</b> 抛错方法：<b>@Model.ActionName</b> 抛错类型：<b>@Model.Exception.GetType()</b> ???</p> ???<p> ???????异常信息:@Model.Exception.Message ???</p> ???<p> ???????堆栈信息：@Model.Exception.StackTrace ???</p></body></html>结果：
MVC教程九：异常过滤器
原文地址：https://www.cnblogs.com/dotnet261010/p/9005952.html