MVC路由解析---MapRoute-白红宇

MVC路由解析---MapRoute

阅读量：5068 次

发布时间：2019-06-12

本文共 8985 字，大约阅读时间需要 29 分钟。

文章引导

引言

前面我们讲了IgnoreRoute

现在我们讲讲核心的MapRoute，还是提前准备Reflection工具，若是没准备，可以看“”MVC路由深入详解1---IgnoreRoute”中的System.Web.dll源码

一.RouteCollection

我们来看看RouteCollection.MapRoute，截图如下：

相信大家看到了RouteCollectionExtensions是一个静态类，是对RouteCollection的扩展（关于扩展方法的大家可以百度，此处不做详细描述）。好家伙，我们看看这个扩展方法走向何方（这个时候就是Reflection发挥作用的时候了）。

引用“”MVC路由深入详解1---IgnoreRoute”中的内容，看看MapRoute的参数传入的是什么：

name: "Default"

url: "{controller}/{action}/{id}"

defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional } --->这是个匿名类型

我们看看扩展方法去了哪里：

public static (this routes, name, url, defaults) => routes.(name, url, defaults, null);

我们接着往下走

public static (this routes, name, url, defaults, constraints) =>routes.(name, url, defaults, constraints, null);

接着

public Route MapRoute(string name,string url,object defaults,object constraints=null,string[] param=null)        {            if(url==null)            {                throw new ArgumentNullException("url");            }            Route route = new Route(url, new MvcRouteHandler())            {                Defaults=CreateRouteValueDictionaryUncached(defaults),                Constraints=CreateRouteValueDictionaryUncached(constraints),                DataTokens=new System.Web.Routing.RouteValueDictionary()            };            ConstraintValidation.Validate(route);            if ((param != null) && (param.Length > 0))            {                route.DataTokens["Namespaces"] = param;            }            Add(name, route);            return route;        }

上面新建了一个Route,Route就是一条具体的路由，new Route(url, new MvcRouteHandler())传入规则url和new MvcRouteHandler()。

二.CreateRouteValueDictionaryUncached

private static System.Web.Routing.RouteValueDictionary CreateRouteValueDictionaryUncached(object values)        {            IDictionary
     
       dictionary = values as IDictionary
      
       ;            if (dictionary != null)            {                return new System.Web.Routing.RouteValueDictionary(dictionary);            }            return System.Web.WebPages.TypeHelper.ObjectToDictionaryUncached(values);        }

三.MvcRouteHandler

我们继续拆解MvcRouteHandler

public class MvcRouteHandler: System.Web.Routing.IRouteHandler    {        System.Web.Mvc.IControllerFactory _controllerFactory;        public MvcRouteHandler() { }        public MvcRouteHandler(System.Web.Mvc.IControllerFactory controllFactory)        {            _controllerFactory = controllFactory;        }        protected virtual IHttpHandler GetHttpHandler(System.Web.Routing.RequestContext requestContext)        {            //SetSessionStateBehavior:在派生类重写时，设置支持HTTP请求所必须的会话状态行为的类型 requestContext.HttpContext.SetSessionStateBehavior(GetSessionStateBehavior(requestContext)); return new MvcHandler(requestContext); } IHttpHandler System.Web.Routing.IRouteHandler.GetHttpHandler(System.Web.Routing.RequestContext requestContext) { return GetHttpHandler(requestContext); } protected virtual System.Web.SessionState.SessionStateBehavior GetSessionStateBehavior(System.Web.Routing.RequestContext requestContext) { string str = (string)requestContext.RouteData.Values["controller"]; if (string.IsNullOrEmpty(str)) { throw new InvalidOperationException(System.Web.Mvc.Properties.MvcResources.MvcRouteHandler_RouteValuesHasNoController); } IControllerFactory factory = _controllerFactory ?? ControllerBuilder.Current.GetControllerFactory(); return factory.GetControllerSessionBehavior(requestContext, str); } }

四.RouteValueDictionary

RouteValueDictionary是对Dictionary<string,object>进行包装，下面是RouteValueDictionary拆解

public RouteValueDictionary(object values){    this._dictionary = new Dictionary
     
      (StringComparer.OrdinalIgnoreCase);    this.AddValues(values);}private void AddValues(object values){    if (values != null)    {        foreach (PropertyDescriptor descriptor in TypeDescriptor.GetProperties(values))        {            object obj2 = descriptor.GetValue(values);            this.Add(descriptor.Name, obj2);        }    }}

我们来看看效果

五.Add(name,route)

我们来看看这个Add方法：

public void Add(string name, RouteBase item)        {            if (item == null)            {                throw new ArgumentNullException("item");            }            if (!string.IsNullOrEmpty(name) && this._namedMap.ContainsKey(name))            {                object[] args = new object[] { name };                //throw new ArgumentException(string.Format(CultureInfo.CurrentUICulture, System.Web.SR.GetString("RouteCollection_DuplicateName"), args), "name");            }            base.Add(item);            if (!string.IsNullOrEmpty(name))            {                this._namedMap[name] = item;            }        }

里面做了重复路由名称验证，Add方法的第二个参数是RouteBase,我们看看MapRoute方法里传入给Add方法的参数是Route。Route是继承于RouteBase，RouteBase是一个抽象类，这个类是为继承类服务的，里面定义了GetRouteData和GetVirtualPath两个抽象方法。

GetRouteData：解析请求url，提取数据，如：/home/index 得到：controller/home,action/index提取得到的数据会包装成RouteData

GetVirtualPath:生成URL

六.RouteBase Route

public abstract class RouteBase{    // Methods    protected RouteBase();    public abstract RouteData GetRouteData(HttpContextBase httpContext);    public abstract VirtualPathData GetVirtualPath(RequestContext requestContext, RouteValueDictionary values);}

public class Route : RouteBase{    // Fields    private ParsedRoute _parsedRoute;    private string _url;    private const string HttpMethodParameterName = "httpMethod";    // Methods    public Route(string url, IRouteHandler routeHandler);    public Route(string url, RouteValueDictionary defaults, IRouteHandler routeHandler);    public Route(string url, RouteValueDictionary defaults, RouteValueDictionary constraints, IRouteHandler routeHandler);    public Route(string url, RouteValueDictionary defaults, RouteValueDictionary constraints, RouteValueDictionary dataTokens, IRouteHandler routeHandler);    public override RouteData GetRouteData(HttpContextBase httpContext);    public override VirtualPathData GetVirtualPath(RequestContext requestContext, RouteValueDictionary values);    protected virtual bool ProcessConstraint(HttpContextBase httpContext, object constraint, string parameterName, RouteValueDictionary values, RouteDirection routeDirection);    private bool ProcessConstraints(HttpContextBase httpContext, RouteValueDictionary values, RouteDirection routeDirection);    // Properties    public RouteValueDictionary Constraints { get; set; }    public RouteValueDictionary DataTokens { get; set; }    public RouteValueDictionary Defaults { get; set; }    public IRouteHandler RouteHandler { get; set; }    public string Url { get; set; }}

Route添加了几个属性

Constraints:保存约束规则，最终保存为RouteValueDictionary

DataTokens:附加参数，指定controller的空间命名也放在这里。

Defaults:保存规则的默认值

url:规则URL

我们来看看GetRouteData，我们看看RouteData routeData=RouteCollection.GetRouteData(context)。

public RouteData GetRouteData(HttpContextBase httpContext){    if (httpContext == null)    {        throw new ArgumentNullException("httpContext");    }    if (httpContext.Request == null)    {        throw new ArgumentException(RoutingResources.RouteTable_ContextMissingRequest, "httpContext");    }    if (!this.RouteExistingFiles)    {        string appRelativeCurrentExecutionFilePath = httpContext.Request.AppRelativeCurrentExecutionFilePath;        if (((appRelativeCurrentExecutionFilePath != "~/") && (this._vpp != null)) && (this._vpp.FileExists(appRelativeCurrentExecutionFilePath) || this._vpp.DirectoryExists(appRelativeCurrentExecutionFilePath)))        {            return null;        }    }    using (this.GetReadLock())    {        foreach (RouteBase base2 in this)        {            RouteData routeData = base2.GetRouteData(httpContext);            if (routeData != null)            {                return routeData;            }        }    }    return null;}

上述代码中最后通过递归遍历自己所有的路由规则，分别调用我们所有注册在RouteTable.Routes--->RouteCollection。

我们还注意到上面有这么一段：

if (!this.RouteExistingFiles)

{

string appRelativeCurrentExecutionFilePath = httpContext.Request.AppRelativeCurrentExecutionFilePath;

if (((appRelativeCurrentExecutionFilePath != "~/") && (this._vpp != null)) && (this._vpp.FileExists(appRelativeCurrentExecutionFilePath) || this._vpp.DirectoryExists(appRelativeCurrentExecutionFilePath)))

{

return null;

}

RouteCollection 有这么一个属性RouteExistingFiles.当为false时，就检测请求的路径地址是否己经存在文件或目录，如果存在，则直接不走路由了，直接返回null，默认就是false，我们可以实验一下。当然这里是忽略了根目录的，不然默认我们 http://www.xxx.com/ 也不能访问了。

public static void RegisterRoutes(RouteCollection routes)

{

routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

routes.MapRoute(

"Default", // Route name

"{controller}/{action}/{id}", // URL with parameters

new { controller = "Home", action = "Index", id = UrlParameter.Optional }, // Parameter defaults

new string[] { "MVCTest.Controllers" }

);

}

这里是默认的路由注册，按理说我们访问 home 时，会去到 home controller 的 index，但是我们在在项目里加一个 home 目录，如下图。