ASP.NET MVC 路由进阶(之二)--自定义路由约束

3.自定义路由约束

什么叫自定义路由约束呢？假如路由格式为archive/{year}/{month}/{day},其中year，month，day是有约束条件的，必须是数字，而且有一定范围。

这时候，我们就可以设置约束类，进行自定义路由约束了。

第一步： 我们先添加年份限制类 YearRouteConstraint。请看代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Routing;
using System.Globalization;

namespace MvcMobileDMS.App_Start
{
    public class YearRouteConstraint:IRouteConstraint
    {
        public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
        {
            if (routeDirection == RouteDirection.IncomingRequest && parameterName.ToLower(CultureInfo.InvariantCulture) == "year")
            {
                try
                {
                    int year = Convert.ToInt32(values["year"]);
                    if ((year >= 1900) && (year <= 2100)) return true;
                }
                catch
                {
                    return false;
                }
            }
            return false;
        }
    }
}

第二步：添加月份限制类 MonthRouteConstraint。请看代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Routing;
using System.Globalization;

namespace MvcMobileDMS.App_Start
{
    public class MonthRouteConstraint : IRouteConstraint
    {
        public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
        {
            if (routeDirection == RouteDirection.IncomingRequest && parameterName.ToLower(CultureInfo.InvariantCulture) == "month")
            {
                try
                {
                    int month = Convert.ToInt32(values["month"]);
                    if ((month >= 1) && (month <= 12)) return true;
                }
                catch
                {
                    return false;
                }
            }
            return false;
        }
    }
}

第三步：添加日期限制类DayRouteConstraint。请看代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Routing;
using System.Globalization;

namespace MvcMobileDMS.App_Start
{
    public class DayRouteConstraint : IRouteConstraint
    {
        public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
        {
            if (routeDirection == RouteDirection.IncomingRequest && parameterName.ToLower(CultureInfo.InvariantCulture) == "day")
            {
                try
                {
                    int month = Convert.ToInt32(values["month"]);
                    int day = Convert.ToInt32(values["day"]);
                    if (day < 1) return false;
                    switch (month)
                    {
                        case 1:
                        case 3:
                        case 5:
                        case 7:
                        case 8:
                        case 10:
                        case 12:
                            if (day <= 31) return true;
                            break;
                        case 2:
                            if (day <= 28) return true;
                            break;
                        case 4:
                        case 6:
                        case 9:
                        case 11:
                            if (day <= 30) return true;
                            break;
                    }
                }
                catch
                {
                    return false;
                }
            }
            return false;
        }
    }
}

ok，三个限制类已经写完了，需要在全局应用程序类中配置路由，见代码清单：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;

namespace MvcMobileDMS
{
    public class RouteConfig
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "DMS", action = "logon", id = UrlParameter.Optional }
            );

            routes.MapRoute(
                "Archive",
                "archive/{year}/{month}/{day}",
                new { controller = "Archive", action = "Index", year = "", month = "", day = "" }, new { year = new MvcMobileDMS.App_Start.YearRouteConstraint(), month = new MvcMobileDMS.App_Start.MonthRouteConstraint(), day =new MvcMobileDMS.App_Start.DayRouteConstraint() }
            );

        }
    }
}

我们看看运行结果：

当我在浏览器地址栏输入以下地址时，http://localhost:7449/archive/1988/9/10，如下截图：

而当我输入不满足约束条件的地址时，http://localhost:7449/archive/1988/09/34，如下截图：

由此可见，当输入非法路由时，路由系统会当做错误处理，所以我们可以为MVC路由设置约束，以规范路由格式。

好了，今天写到这里。希望能对你有所帮助O(∩_∩)O哈哈~