概述
关于ASP.NET MVC中路由有两个基本核心作用,一是通过Http请求中的Url参数等信息获取路由数据(RouteData),路由数据包含了area、controller、action的名称等信息。只有获取了匹配的路由数据,才有可能转入ASP.NET MVC管道;二是根据由规则生成Url,比如要根据某些数据生成View上显示的链接。
Orchard对路由进行扩展主要基于如下原因:
(1)、路由定义在各个模块中。在Orchard应用程序初始化时将分散在各个模块的路由定义收集起来统一注册。
(2)、路由定义一次,对于多Shell系统,则会被多次注册以匹配Shell的前缀。
(3)、当请求进入时需要确认进入了哪个Shell,并且在成Url时也需要加上Shell的Url前缀。
(4)、将WorkContextAccessor放入路由数据的DataTokens中。WorkContextAccessor工作上下文访问器封装了HTTP上下文、Autofa容器等信息。
(5)、重置IRouteHandler和IHttpHandler,以包含WorkContextAccessor、包含Shell的配置(ShellSettings)、包含应用程序域中正在运行的Shell(RunningShellTable)、设置SessionState等。
请留意下文描述中System.Web.Routing.RouteBase、Route、RouteData、Orchard.Mvc.Routes.ShellRoute、Orchard.Mvc.Routes.RouteDescriptor及Orchard.Mvc.Routes.HttpRouteDescriptor之间的关系。
一、路由的定义
如果Orchard模块需要路由,并不是在Global.asax.cs等地方直接配置,而是先将路由定义在模块源码一个或多个实现了Orchard.Mvc.Routes.IRouteProvide.IRouteProvider接口或Orchard.WebApi.Routes.IHttpRouteProvider的类的IEnumerable<RouteDescriptor> GetRoutes()方法中。
如Orchard.Blogs模块就定义了一个名为Routes的类,该类就实现了IRouteProvider接口,主要关注GetRoutes方法:
// 以下代码来在Orchard.Blogs.Routes类
public IEnumerable<RouteDescriptor> GetRoutes() {
return new [] {
new RouteDescriptor {
Route = new Route (
"Admin/Blogs/Create",
new RouteValueDictionary {
{"area", "Orchard.Blogs" },
{"controller" , "BlogAdmin"},
{"action", "Create" }
},
new RouteValueDictionary (),
new RouteValueDictionary {
{"area", "Orchard.Blogs" }
},
new MvcRouteHandler ())
},
//......
GetRoutes方法返回一个路由描述RouteDescriptor对象集合。
RouteDescriptor类包装了一个RouteBase类,并有Name和Priority属性:
public class RouteDescriptor {
public string Name { get; set; }
public int Priority { get; set; }
public RouteBase Route { get; set; }
public SessionStateBehavior SessionState { get; set; }
}
一般在定义路由时用到的是Route类,它继承了RouteBase类。
通过Priority属性,我们可以更好的控制路由的注册顺序,而不是按定义的先后顺序进行注册。
在路由注册时,通过一系列的RouteDescriptor对象就够获取到对应的RouteBase对象了。
IHttpRouteProvider接口的实现类的作用类似,只是专为WebApi服务而已。有兴趣的可以看看Orchard.Mvc.Routes.StandardExtensionRouteProvider类,顺便也留意一下HttpRouteDescriptor:RouteDescriptor类。
二、路由的注册
在Shell被激活时,会将分散到不同的模块的路由收集起来,并由RoutePublisher注册到全局路由表中:
// 以下代码来在Orchard.Environment.DefaultOrchardShell类
public void Activate() {
var allRoutes = new List< RouteDescriptor>();
allRoutes.AddRange(_routeProviders.SelectMany(provider => provider.GetRoutes()));
allRoutes.AddRange(_httpRouteProviders.SelectMany(provider => provider.GetRoutes()));
_routePublisher.Publish(allRoutes);
_modelBinderPublisher.Publish(_modelBinderProviders.SelectMany(provider => provider.GetModelBinders()));
using (var events = _eventsFactory()) {
events.Value.Activated();
}
_sweepGenerator.Activate();
}
_routeProviders是一个IEnumerable<IRouteProvider>型的私有字段,Autofac在创建DefaultOrchardShell对象时会通过构造器注入的方式初始化该字段。实际上就是相应Shell需要用到的各个模块中的的IRouteProvider对象,通过调用IRouteProvider.GetRoutes方法则可将RouteDescriptor对象收集起来。
_httpRouteProviders是一个IEnumerable<IHttpRouteProvider>型私有字段,实际上IHttpRouteProvider接口IRouteProvider接口完全一样。_httpRouteProviders和_routeProviders的初始化方式也一样。不同的是_httpRouteProviders是为WebApi服务的。
_routePublisher是一个Orchard.Mvc.Routes.RoutePublisher对象,其Publish方法中,将RouteDescriptor对象对应的RouteBase(一般为Route)对象,包装成ShellRoute对象注册到MVC的全局路由表中:
// 以下代码来在Orchard.Mvc.Routes.RoutePublisher类
public void Publish(IEnumerable <RouteDescriptor> routes) {
var routesArray = routes
.OrderByDescending(r => r.Priority)
.ToArray();
// this is not called often, but is intended to surface problems before
// the actual collection is modified
var preloading = new RouteCollection();
foreach (var routeDescriptor in routesArray) {
// extract the WebApi route implementation
var httpRouteDescriptor = routeDescriptor as HttpRouteDescriptor;
if (httpRouteDescriptor != null ) {
var httpRouteCollection = new RouteCollection();
httpRouteCollection.MapHttpRoute(httpRouteDescriptor.Name, httpRouteDescriptor.RouteTemplate, httpRouteDescriptor.Defaults);
routeDescriptor.Route = httpRouteCollection.First();
}
preloading.Add(routeDescriptor.Name, routeDescriptor.Route);
}
using (_routeCollection.GetWriteLock()) {
// existing routes are removed while the collection is briefly inaccessable
var cropArray = _routeCollection
.OfType< ShellRoute>()
.Where(sr => sr.ShellSettingsName == _shellSettings.Name)
.ToArray();
foreach(var crop in cropArray) {
_routeCollection.Remove(crop);
}
// new routes are added
foreach (var routeDescriptor in routesArray) {
// Loading session state information.
var defaultSessionState = SessionStateBehavior .Default;
ExtensionDescriptor extensionDescriptor = null ;
if(routeDescriptor.Route is Route) {
object extensionId;
var route = routeDescriptor.Route as Route;
if(route.DataTokens != null && route.DataTokens.TryGetValue("area", out extensionId) ||
route.Defaults != null && route.Defaults.TryGetValue("area", out extensionId)) {
extensionDescriptor = _extensionManager.GetExtension(extensionId.ToString());
}
}
else if (routeDescriptor.Route is IRouteWithArea) {
var route = routeDescriptor.Route as IRouteWithArea;
extensionDescriptor = _extensionManager.GetExtension(route.Area);
}
if (extensionDescriptor != null ) {
// if session state is not define explicitly, use the one define for the extension
if (routeDescriptor.SessionState == SessionStateBehavior.Default) {
Enum.TryParse(extensionDescriptor.SessionState, true /*ignoreCase*/, out defaultSessionState);
}
}
// Route-level setting overrides module-level setting (from manifest).
var sessionStateBehavior = routeDescriptor.SessionState == SessionStateBehavior.Default ? defaultSessionState : routeDescriptor.SessionState ;
var shellRoute = new ShellRoute(routeDescriptor.Route, _shellSettings, _workContextAccessor, _runningShellTable) {
IsHttpRoute = routeDescriptor is HttpRouteDescriptor ,
SessionState = sessionStateBehavior
};
_routeCollection.Add(routeDescriptor.Name, shellRoute);
}
}
}
ShellRoute类通过装饰器模式包装了一个System.Web.Routing.RouteBase类,其本身也是继承自RouteBase类。
要特别留意创建ShellRoute对象时为构造函数提供的几个参数:
routeDescriptor.Route:ShellRoute所包含的Route。 _shellSettings:ShellRoute对应的ShellSettings。
_workContextAccessor:WorkContextAccessor是Shell级的单例,其在WorkContextModule中被注册。它包装了一个Shell相关的Autofac子容器,通过该容器可以Resolve出Shell作用域的对象。
_runningShellTable:正在运行的Shell对应的ShellSettings表。
三、路由映射——根据请求路径查找匹配的路由数据(RouteData)
从Url角度上讲,怎么区分两个Shell呢?首先两个Shell可以拥有不同的域名,或者拥有相同的域名但不同的Url前缀。如:
(1)、其中一个Shell无域名
Shell 1 - 无
Shell 2 - www.yourdomain2.com
(2)、不同的域名
Shell 1 - www.yourdomain1.com
Shell 2 - www.yourdomain2.com
(3)、相同的域名,不同的Url前缀
Shell 1 - www.yourdomain1.com/abc
Shell 2 - www.yourdomain1.com/def
(4)、相同的域名,只有一个Shell的Url前缀
Shell 1 - www.yourdomain1.com
Shell 2 - www.yourdomain1.com/def
这种情况会先检查Url是否匹配Shell 2,然后再检查是否匹配Shell 1。Url前缀长度越长,越优先检查。
引申:
Shell 1 - www.yourdomain1.com/abc/def
Shell 2 - www.yourdomain1.com/abc
(5)、一个Shell可以对应单个或多个域名
Shell 1 - www.yourdomain1.com
Shell 2 - www.yourdomain2.com和 www.yourdomain3.com
(6)、更复杂的配置
为了方便分析,这里我们假设Orchard中配置了两个Shell,ShellSettings设置如下: Shell 1:ShellSettings.RequestUrlHost ="www.yourdomain1.com",ShellSettings.RequestUrlPrefix=String.Empty
Shell 2:ShellSettings.RequestUrlHost ="www.yourdomain2.com",ShellSettings.RequestUrlPrefix="abc"
并且某模块被这两个Shell使用,该模块的Routes:IRouteProvider类中定义了一个匹配"{controller}/{action}"的路由。需要注意一点,虽然这里只定义一个路由,但是这里两个Shell都会用到,所以会被包装成两个ShellRoute对象注册到全局路由表中。
再假设一个新的Http请求进入,Url是:http://www.yourdomain2.com/abc/home/index
首先System.Web.Routing.UrlRouteModule会遍历全局路由表中的路由,期待获取一个RouteData对象。当遍历到我们刚刚注册的路由时,会调用路由的GetRouteData方法:
// 以下代码来在Orchard.Mvc.Routes.ShellRoute类
public override RouteData GetRouteData( HttpContextBase httpContext) {
// locate appropriate shell settings for request
var settings = _runningShellTable.Match(httpContext);
// only proceed if there was a match, and it was for this client
if (settings == null || settings.Name != _shellSettings.Name)
return null ;
var effectiveHttpContext = httpContext;
if (_urlPrefix != null )
effectiveHttpContext = new UrlPrefixAdjustedHttpContext (httpContext, _urlPrefix);
var routeData = _route.GetRouteData(effectiveHttpContext);
if (routeData == null )
return null ;
// push provided session state behavior to underlying MvcHandler
effectiveHttpContext.SetSessionStateBehavior(SessionState);
// otherwise wrap handler and return it
routeData.RouteHandler = new RouteHandler (_workContextAccessor, routeData.RouteHandler, SessionState);
routeData.DataTokens[ "IWorkContextAccessor"] = _workContextAccessor;
if (IsHttpRoute) {
routeData.Values[ "IWorkContextAccessor"] = _workContextAccessor; // for WebApi
}
return routeData;
}
Shell被成功激活后,其对应的ShellSettings会存入在一个RunningShellTable对象中。在这里也就是_runningShellTable变量。
根据传入的Url,找到匹配的ShellSettings存入局部变量_settings:
var settings = _runningShellTable.Match(httpContext);
下面看看Match的过程:
/// 该方法位于Orchard.Environment.RunningShellTable类中
public ShellSettings Match(string host, string appRelativePath) {
var hostLength = host.IndexOf(‘:‘ );
if (hostLength != -1)
host = host.Substring(0, hostLength);
var mostQualifiedMatch = _shellsByHost
.Where(group => host.EndsWith(group.Key, StringComparison.OrdinalIgnoreCase))
.SelectMany(group => group
.OrderByDescending(settings => (settings.RequestUrlPrefix ?? string.Empty).Length))
.FirstOrDefault(settings => settings.State.CurrentState != TenantState.State .Disabled && appRelativePath.StartsWith("~/" + (settings.RequestUrlPrefix ?? string.Empty), StringComparison.OrdinalIgnoreCase));
return mostQualifiedMatch ?? _fallback;
}
所以http://www.yourdomain2.com/abc/home/index匹配到的Shell为Shell 2。
GetRouteData方法接下来有个判断:
if (settings == null || settings.Name != _shellSettings.Name)
return null ;
settings可能为null这好理解,但其Name值为什么可能不相等呢?请留意RunningShellTable.Match方法的最后一行的_fallback变量,这里就不再详述。
如果Shell包含Url前缀,则调整HttpContext:
var effectiveHttpContext = httpContext;
if (_urlPrefix != null )
effectiveHttpContext = new UrlPrefixAdjustedHttpContext (httpContext, _urlPrefix);
_urlPrefix是一个Orchard.Mvc.Routes.UrlPrefix对象,它包装了一个用来表示Shell的Url前缀字符串。如果RoutePublisher在创建ShellRoute时,传入的_shellSettings参数的RequestUrlPrefix属性不为null或空,则_urlPrefix不会为null。UrlPrefix类有两个重要的方法:RemoveLeadingSegments和PrependLeadingSegments。如果_urlPrefix包装的Url前缀字符串为"abc",则_urlPrefix.RemoveLeadingSegments("~/abc/home/index")返回的值是"~/abc/home/index",而_urlPrefix.PrependLeadingSegments("~/home/index")返回的值是"~/abc/home/index"。
UrlPrefixAdjustedHttpContext类最主要的目的是替换掉原来的HttpRequest,以使得HttpRequest的AppRelativeCurrentExecutionFilePath属性能够返回一个去掉Url前缀的值。这样做得目的是为了能够按"常规"方式获取到RouteData。
如ShellRoute的RequestUrlPrefix属性值为"abc",请求的Url是:
http://www.yourdomain2.com/abc/home/index
则AppRelativeCurrentExecutionFilePath返回的值是:
~/home/index
_route.GetRouteData方法的调用,也就是刚才说的"常规"方式:
var routeData = _route.GetRouteData(effectiveHttpContext);
if (routeData == null )
return null ;
GetRouteData最后的代码也简单:
// push provided session state behavior to underlying MvcHandler
effectiveHttpContext.SetSessionStateBehavior(SessionState);
// otherwise wrap handler and return it
routeData.RouteHandler = new RouteHandler (_workContextAccessor, routeData.RouteHandler, SessionState);
routeData.DataTokens[ "IWorkContextAccessor"] = _workContextAccessor;
if (IsHttpRoute) {
routeData.Values[ "IWorkContextAccessor"] = _workContextAccessor; // for WebApi
}
这里的RouteHandler类是ShellRoute的私有嵌套类,其通过装饰器模式包装了一个IRouteHandler对象。相关类型还有私有嵌套类HttpHandler和HttpAsyncHandler。RouteHandler是为了Autofac容器的应用到IHttpHandler中。
在上面提到的Orchard.Blogs.Routes类中,定义的Route的RouteHandler是MvcRouteHandler,这里重新包装成RouteHandler对象再赋给routeData的RouteHandler属性。
后面再将_workContextAccessor保存进routeData的DataTokens中。
四、根据路由规则生成Url
public override VirtualPathData GetVirtualPath( RequestContext requestContext, RouteValueDictionary values) {
// locate appropriate shell settings for request
var settings = _runningShellTable.Match(requestContext.HttpContext);
// only proceed if there was a match, and it was for this client
if (settings == null || settings.Name != _shellSettings.Name)
return null ;
var effectiveRequestContext = requestContext;
if (_urlPrefix != null )
effectiveRequestContext = new RequestContext (new UrlPrefixAdjustedHttpContext (requestContext.HttpContext, _urlPrefix), requestContext.RouteData);
var virtualPath = _route.GetVirtualPath(effectiveRequestContext, values);
if (virtualPath == null )
return null ;
if (_urlPrefix != null )
virtualPath.VirtualPath = _urlPrefix.PrependLeadingSegments(virtualPath.VirtualPath);
return virtualPath;
}
前面几行代码和GetRouteData类似,关注点在UrlPrefixAdjustedHttpContext类和UrlPrefix类,在分析GetRouteData方法时已有简单分析。
相关类型:
Orchard.Mvc.Routes.ShellRoute : RouteBase, IRouteWithArea
Orchard.Mvc.Routes.RouteDescriptor
Orchard.Mvc.Routes.HttpRouteDescriptor
Orchard.Mvc.Routes.IRouteProvider : IDependency
Orchard.Mvc.Routes.IHttpRouteProvider : IDependency
Orchard.Mvc.Routes.DefaultRouteProvider:IRouteProvider
Orchard.Mvc.Routes.StandardExtensionRouteProvider:IRouteProvider
Orchard.Mvc.Routes.RoutePublisher : IRoutePublisher
Orchard.Mvc.Routes.UrlPrefix
Orchard.Mvc.Routes.UrlPrefixAdjustedHttpContext
Orchard.Environment.RunningShellTable : IRunningShellTable
Orchard.Environment.WorkContextAccessor : IWorkContextAccessor
Orchard.WorkContext