給Asp.Net MVC及WebApi添加路由優(yōu)先級

WindySky 2017-10-10

展開全文

一、為什么需要路由優(yōu)先級

大家都知道我們在Asp.Net MVC項目或WebApi項目中注冊路由是沒有優(yōu)先級的，當(dāng)項目比較大、或有多個區(qū)域、或多個Web項目、或采用插件式框架開發(fā)時，我們的路由注冊很可能不是寫在一個文件中的，而是分散在很多不同項目的文件中，這樣一來，路由的優(yōu)先級的問題就突顯出來了。

比如： App_Start/RouteConfig.cs中

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

Areas/Admin/AdminAreaRegistration.cs中

context.MapRoute(
    name: "Login",    
    url: "login",
    defaults: new { area = "Admin", controller = "Account", action = "Login", id = UrlParameter.Optional },
    namespaces: new string[] { "Wenku.Admin.Controllers" }
);

假如是先注冊上面那個通用的default路由，再注冊這個login的路由，那么無論怎么樣，都會先匹配第一個滿足條件的路由，也就是第兩個路由注冊是無效的。
造成這個問題的原因就是這兩個路由注冊的順序問題，而Asp.Net MVC及WebApi中注冊路由都沒有優(yōu)先級這個概念，所以今天我們就是要自己實現(xiàn)這個想法，在注冊路由時加入一個優(yōu)先級的概念。

二、解決思路

1、先分析路由注冊的入口，比如我們新建一個mvc4.0的項目

public class MvcApplication : System.Web.HttpApplication
{
    protected void Application_Start()
    {
        AreaRegistration.RegisterAllAreas();

        WebApiConfig.Register(GlobalConfiguration.Configuration);
        FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
        RouteConfig.RegisterRoutes(RouteTable.Routes);
    }
}

Mvc路由的注冊入口有兩個：
a. AreaRegistration.RegisterAllAreas(); 注冊區(qū)域路由
b. RouteConfig.RegisterRoutes(RouteTable.Routes); 注冊項目路由

WebApi路由注冊入口有一個：
WebApiConfig.Register(GlobalConfiguration.Configuration); 注冊WebApi路由

2、注冊路由的處理類分析
    AreaRegistrationContext
    RouteCollection
    HttpRouteCollection

注冊路由時主要是由這三個類來注冊處理路由的。

3、路由優(yōu)先級方案
    a、更改路由的注冊入口
    b、自定義一個路由的結(jié)構(gòu)類RoutePriority及HttpRoutePriority，這兩個類下面都有Priority這個屬性
    c、自定一個RegistrationContext來注冊路由，注冊的對象為上述自定義路由。
    d、所有的路由注冊完成之后再按優(yōu)先順序添加到RouteCollection及HttpRouteCollection中實際生效。

三、具體實現(xiàn)

1、路由定義

public class RoutePriority : Route
{
    public string Name { get; set; }
    public int Priority { get; set; }

    public RoutePriority(string url, IRouteHandler routeHandler)
        : base(url,routeHandler)
    {

    }
}

public class HttpRoutePriority
{
    public string Name { get; set; }
    public int Priority { get; set; }
    public string RouteTemplate{get;set;}
    public object Defaults{get;set;}
    public object Constraints{get;set;} 
    public HttpMessageHandler Handler{get;set;}
}

2、定義路由注冊的接口

public interface IRouteRegister
{
    void Register(RegistrationContext context);
}

3、定義路由注冊上下文類

public class RegistrationContext
{
    #region mvc
    public List<RoutePriority> Routes = new List<RoutePriority>();

    public RoutePriority MapRoute(string name, string url,int priority=0)
    {
        return MapRoute(name, url, (object)null /* defaults */, priority);
    }

    public RoutePriority MapRoute(string name, string url, object defaults, int priority = 0)
    {
        return MapRoute(name, url, defaults, (object)null /* constraints */, priority);
    }

    public RoutePriority MapRoute(string name, string url, object defaults, object constraints, int priority = 0)
    {
        return MapRoute(name, url, defaults, constraints, null /* namespaces */, priority);
    }

    public RoutePriority MapRoute(string name, string url, string[] namespaces, int priority = 0)
    {
        return MapRoute(name, url, (object)null /* defaults */, namespaces, priority);
    }

    public RoutePriority MapRoute(string name, string url, object defaults, string[] namespaces,int priority=0)
    {
        return MapRoute(name, url, defaults, null /* constraints */, namespaces, priority);
    }

    public RoutePriority MapRoute(string name, string url, object defaults, object constraints, string[] namespaces, int priority = 0)
    {
        var route = MapPriorityRoute(name, url, defaults, constraints, namespaces, priority);
        var areaName = GetAreaName(defaults);
        route.DataTokens["area"] = areaName;

        // disabling the namespace lookup fallback mechanism keeps this areas from accidentally picking up
        // controllers belonging to other areas
        bool useNamespaceFallback = (namespaces == null || namespaces.Length == 0);
        route.DataTokens["UseNamespaceFallback"] = useNamespaceFallback;

        return route;
    }

    private static string GetAreaName(object defaults)
    {
        if (defaults != null)
        {
            var property = defaults.GetType().GetProperty("area");
            if (property != null)
                return (string)property.GetValue(defaults, null);
        }

        return null;
    }

    private RoutePriority MapPriorityRoute(string name, string url, object defaults, object constraints, string[] namespaces,int priority)
    {
        if (url == null)
        {
            throw new ArgumentNullException("url");
        }

        var route = new RoutePriority(url, new MvcRouteHandler())
        {
            Name = name,
            Priority = priority,
            Defaults = CreateRouteValueDictionary(defaults),
            Constraints = CreateRouteValueDictionary(constraints),
            DataTokens = new RouteValueDictionary()
        };

        if ((namespaces != null) && (namespaces.Length > 0))
        {
            route.DataTokens["Namespaces"] = namespaces;
        }

        Routes.Add(route);
        return route;
    }

    private static RouteValueDictionary CreateRouteValueDictionary(object values)
    {
        var dictionary = values as IDictionary<string, object>;
        if (dictionary != null)
        {
            return new RouteValueDictionary(dictionary);
        }

        return new RouteValueDictionary(values);
    }
    #endregion

    #region http
    public List<HttpRoutePriority> HttpRoutes = new List<HttpRoutePriority>();

    public HttpRoutePriority MapHttpRoute(string name, string routeTemplate, int priority = 0)
    {
        return MapHttpRoute(name, routeTemplate, defaults: null, constraints: null, handler: null, priority: priority);
    }

    public HttpRoutePriority MapHttpRoute(string name, string routeTemplate, object defaults, int priority = 0)
    {
        return MapHttpRoute(name, routeTemplate, defaults, constraints: null, handler: null, priority: priority);
    }

    public HttpRoutePriority MapHttpRoute(string name, string routeTemplate, object defaults, object constraints, int priority = 0)
    {
        return MapHttpRoute(name, routeTemplate, defaults, constraints, handler: null, priority: priority);
    }

    public HttpRoutePriority MapHttpRoute(string name, string routeTemplate, object defaults, object constraints, HttpMessageHandler handler, int priority = 0)
    {
        var httpRoute = new HttpRoutePriority();
        httpRoute.Name = name;
        httpRoute.RouteTemplate = routeTemplate;
        httpRoute.Defaults = defaults;
        httpRoute.Constraints = constraints;
        httpRoute.Handler = handler;
        httpRoute.Priority = priority;
        HttpRoutes.Add(httpRoute);

        return httpRoute;
    }
    #endregion
}

4、把路由注冊處理方法添加到Configuration類中

public static Configuration RegisterRoutePriority(this Configuration config)
{
    var typesSoFar = new List<Type>();
    var assemblies = GetReferencedAssemblies();
    foreach (Assembly assembly in assemblies)
    {
        var types = assembly.GetTypes().Where(t => typeof(IRouteRegister).IsAssignableFrom(t) && !t.IsAbstract && !t.IsInterface);
        typesSoFar.AddRange(types);
    }

    var context = new RegistrationContext();
    foreach (var type in typesSoFar)
    {
        var obj = (IRouteRegister)Activator.CreateInstance(type);
        obj.Register(context);
    }

    foreach (var route in context.HttpRoutes.OrderByDescending(x => x.Priority))
        GlobalConfiguration.Configuration.Routes.MapHttpRoute(route.Name, route.RouteTemplate, route.Defaults, route.Constraints, route.Handler);

    foreach (var route in context.Routes.OrderByDescending(x => x.Priority))
        RouteTable.Routes.Add(route.Name, route);

    return config;
}

private static IEnumerable<Assembly> GetReferencedAssemblies()
{
    var assemblies = BuildManager.GetReferencedAssemblies();
    foreach (Assembly assembly in assemblies)
        yield return assembly;
}

這樣一來就大功告成，使用時只需要在Global.asax.cs文件中修改原注冊入口為

public class MvcApplication : System.Web.HttpApplication
{
    protected void Application_Start()
    {
        WebApiConfig.Register(GlobalConfiguration.Configuration);
        FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
        RouteConfig.RegisterRoutes(RouteTable.Routes);

        Configuration.Instance()
            .RegisterComponents()
            .RegisterRoutePriority(); //注冊自定義路由
    }
}

在每個項目中使用只需要要繼承自定義路由注冊接口IRouteRegister，例如：

public class Registration : IRouteRegister
{
    public void Register(RegistrationContext context)
    {
       //注冊后端管理登錄路由
        context.MapRoute(
          name: "Admin_Login",
          url: "Admin/login",
          defaults: new { area = "Admin", controller = "Account", action = "Login", id = UrlParameter.Optional },
          namespaces: new string[] { "Wenku.Admin.Controllers" },
          priority: 11
      );

       //注冊后端管理頁面默認(rèn)路由
        context.MapRoute(
            name: "Admin_default",
            url: "Admin/{controller}/{action}/{id}",
            defaults: new { area = "Admin", controller = "Home", action = "Index", id = UrlParameter.Optional },
            namespaces: new string[] { "Wenku.Admin.Controllers" },
            priority: 10
        );

       //注冊手機(jī)訪問WebApi路由
        context.MapHttpRoute(
            name: "Mobile_Api",
            routeTemplate: "api/mobile/{controller}/{action}/{id}",
            defaults: new
            {
                area = "mobile",
                action = RouteParameter.Optional,
                id = RouteParameter.Optional,
                namespaceName = new string[] { "Wenku.Mobile.Http" }
            },
            constraints: new { action = new StartWithConstraint() },
            priority: 0
        );
    }
}