创建测试工程
分别在vs2013和vs2015中创建mvc项目，并创建First、Second、Three三个Area，每个Area下面创建一个HomeController和Index视图。修改RouteConfig.cs中的路由注册方法，添加命名空间
public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( name: "Default", url: "{controller}/{action}/{id}", defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }, namespaces: new[] { "RouteDebuggerMvc5Demo.Controllers" } ); }
修改三个Area的路由注册方法，添加命名空间：
public class FirstAreaRegistration : AreaRegistration { public override string AreaName { get { return "First"; } } public override void RegisterArea(AreaRegistrationContext context) { context.MapRoute( "First_default", "First/{controller}/{action}/{id}", new { action = "Index", id = UrlParameter.Optional }, namespaces: new[] { "RouteDebuggerMvc5Demo.Areas.First.Controllers" } ); } }
使用nuget添加RouteDebugger引用,在Web.config中配置启用 <add key="RouteDebugger:Enabled" value="true" />，运行起来：
VS2013中升序
| Matches Current Request | Url | Defaults | Constraints | DataTokens |
|---|---|---|---|---|
| False | First/{controller}/{action}/{id} | action = Index, id = UrlParameter.Optional | (empty) | Namespaces = RouteDebuggerMvc5Demo.Areas.First.Controllers, area = First, UseNamespaceFallback = False |
| False | Second/{controller}/{action}/{id} | action = Index, id = UrlParameter.Optional | (empty) | Namespaces = RouteDebuggerMvc5Demo.Areas.Second.Controllers, area = Second, UseNamespaceFallback = False |
| False | Three/{controller}/{action}/{id} | action = Index, id = UrlParameter.Optional | (empty) | Namespaces = RouteDebuggerMvc5Demo.Areas.Three.Controllers, area = Three, UseNamespaceFallback = False |
| False | {resource}.axd/{*pathInfo} | (null) | (empty) | (null) |
| True | {controller}/{action}/{id} | controller = Home, action = Index, id = UrlParameter.Optional | (empty) | Namespaces = RouteDebuggerMvc5Demo.Controllers |
| True | {*catchall} | (null) | (null) | (null) |
VS2015中降序
| Matches Current Request | Url | Defaults | Constraints | DataTokens |
|---|---|---|---|---|
| False | Three/{controller}/{action}/{id} | action = Index, id = UrlParameter.Optional | (empty) | Namespaces = RouteDebuggerDemo.Areas.Three.Controllers, RouteDebuggerDemo, area = Three, UseNamespaceFallback = False |
| False | Second/{controller}/{action}/{id} | action = Index, id = UrlParameter.Optional | (empty) | Namespaces = RouteDebuggerDemo.Areas.Second.Controllers, RouteDebuggerDemo, area = Second, UseNamespaceFallback = False |
| False | First/{controller}/{action}/{id} | action = Index, id = UrlParameter.Optional | (empty) | Namespaces = RouteDebuggerDemo.Areas.First.Controllers, RouteDebuggerDemo, area = First, UseNamespaceFallback = False |
| False | {resource}.axd/{*pathInfo} | (null) | (empty) | (null) |
| True | {controller}/{action}/{id} | controller = Home, action = Index, id = UrlParameter.Optional | (empty) | Namespaces = RouteDebuggerDemo.Controllers, RouteDebuggerDemo |
| True | {*catchall} | (null) | (null) | (null) |
如果在VS2013中的某个路由注册有问题，一直没有显现出来，升级到VS2015后出现了404就有可能是路由匹配顺序导致的。问题参考：Why did the order of Areas in RegisterAllAreas change with Visual Studio 2015?
手动修改路由顺序
默认在 *.csproj文件中的路由顺序是
<Compile Include="AreasFirstControllersHomeController.cs" />
<Compile Include="AreasFirstFirstAreaRegistration.cs" />
<Compile Include="AreasSecondControllersHomeController.cs" />
<Compile Include="AreasSecondSecondAreaRegistration.cs" />
<Compile Include="AreasThreeControllersHomeController.cs" />
<Compile Include="AreasThreeThreeAreaRegistration.cs" />
修改成
<Compile Include="AreasFirstControllersHomeController.cs" />
<Compile Include="AreasFirstFirstAreaRegistration.cs" />
<Compile Include="AreasThreeControllersHomeController.cs" />
<Compile Include="AreasThreeThreeAreaRegistration.cs" />
<Compile Include="AreasSecondControllersHomeController.cs" />
<Compile Include="AreasSecondSecondAreaRegistration.cs" />
重新访问页面查看路由,顺序已经改变了（对比上面VS2015里的顺序），可以通过这种方法把最常用的路由调到最前面，提高匹配速度。经测试添加新的Area后，调整的路由顺序不会变回去，可以放心使用。
参考链接：.Net MVC Area Registration Sequence
RouteDebugger 简介
作者地址：ASP.NET Routing Debugger，代码结构图如下：
程序集属性[assembly: PreApplicationStartMethod(typeof(PreApplicationStart), "Start")] 使PreApplicationStart的Start方法在Application_Start方法之前执行，
public static void Start() { bool flag = Convert.ToBoolean(ConfigurationManager.AppSettings["RouteDebugger:Enabled"]); if (flag) { DynamicModuleUtility.RegisterModule(typeof(RouteDebuggerHttpModule)); } }
最后处理请求的是DebugHttpHandler里的ProcessRequest方法把匹配的路由信息获取出来，代码如下：
//处理请求 public void ProcessRequest(HttpContext context) { HttpRequest request = context.Request; if (!this.IsRoutedRequest(request) || context.Response.ContentType == null || !context.Response.ContentType.Equals("text/html", StringComparison.OrdinalIgnoreCase)) { return; } string text = string.Empty; RequestContext requestContext = request.RequestContext; if (request.QueryString.Count > 0) { RouteValueDictionary routeValueDictionary = new RouteValueDictionary(); foreach (string text2 in request.QueryString.Keys) { if (text2 != null) { routeValueDictionary.Add(text2, request.QueryString[text2]); } } VirtualPathData virtualPath = RouteTable.Routes.GetVirtualPath(requestContext, routeValueDictionary); if (virtualPath != null) { text = "<p><label style="font-weight: bold; font-size: 1.1em;">Generated URL</label>: "; text = text + "<strong style="color: #00a;">" + virtualPath.VirtualPath + "</strong>"; Route route = virtualPath.Route as Route; if (route != null) { text = text + " using the route "" + route.Url + ""</p>"; } } } string text3 = string.Empty; RouteData routeData = requestContext.RouteData; RouteValueDictionary values = routeData.Values; RouteBase route2 = routeData.Route; string text4 = string.Empty; using (RouteTable.Routes.GetReadLock()) { foreach (RouteBase current in RouteTable.Routes) { //查询请求与路由是否匹配 bool flag = current.GetRouteData(requestContext.HttpContext) != null; string isMatchRequest = string.Format("<span{0}>{1}</span>", DebugHttpHandler.BoolStyle(flag), flag); string url = "n/a"; string defaults = "n/a"; string constraints = "n/a"; string dataTokens = "n/a"; Route route3 = this.CastRoute(current); if (route3 != null) { url = route3.Url; defaults = DebugHttpHandler.FormatDictionary(route3.Defaults); constraints = DebugHttpHandler.FormatDictionary(route3.Constraints); dataTokens = DebugHttpHandler.FormatDictionary(route3.DataTokens); } text4 += string.Format("<tr><td>{0}</td><td>{1}</td><td>{2}</td><td>{3}</td><td>{4}</td></tr>", new object[] { isMatchRequest, url, defaults, constraints, dataTokens }); } } string text10 = "n/a"; string text11 = ""; if (!(route2 is DebugRoute)) { foreach (string current2 in values.Keys) { text3 += string.Format(" <tr><td>{0}</td><td>{1} </td></tr>", current2, values[current2]); } foreach (string current3 in routeData.DataTokens.Keys) { text11 += string.Format(" <tr><td>{0}</td><td>{1} </td></tr>", current3, routeData.DataTokens[current3]); } Route route4 = route2 as Route; if (route4 != null) { text10 = route4.Url; } } else { text10 = string.Format("<strong{0}>NO MATCH!</strong>", DebugHttpHandler.BoolStyle(false)); } text3 = "text3"; text10 = "text10"; text4 = "text4"; text11 = "text11"; text = "text"; context.Response.Write(string.Format("<html> <div id="haackroutedebugger" style="background-color: #fff; padding-bottom: 10px;"> <style> #haackroutedebugger, #haackroutedebugger td, #haackroutedebugger th {{background-color: #fff; font-family: verdana, helvetica, san-serif; font-size: small;}} #haackroutedebugger tr.header td, #haackroutedebugger tr.header th {{background-color: #ffc;}} </style> <hr style=" 100%; border: solid 1px #000; margin:0; padding:0;" /> <h1 style="margin: 0; padding: 4px; border-bottom: solid 1px #bbb; padding-left: 10px; font-size: 1.2em; background-color: #ffc;">Route Debugger</h1> <div id="main" style="margin-top:0; padding: 0 10px;"> <p style="font-size: .9em; padding-top:0"> Type in a url in the address bar to see which defined routes match it. A {{*catchall}} route is added to the list of routes automatically in case none of your routes match. </p> <p style="font-size: .9em;"> To generate URLs using routing, supply route values via the query string. example: <code>http://localhost:14230/?id=123</code> </p> <p><label style="font-weight: bold; font-size: 1.1em;">Matched Route</label>: {1}</p> {5} <div style="float: left;"> <table border="1" cellpadding="3" cellspacing="0" width="300"> <caption style="font-weight: bold;">Route Data</caption> <tr class="header"><th>Key</th><th>Value</th></tr> {0} </table> </div> <div style="float: left; margin-left: 10px;"> <table border="1" cellpadding="3" cellspacing="0" width="300"> <caption style="font-weight: bold;">Data Tokens</caption> <tr class="header"><th>Key</th><th>Value</th></tr> {4} </table> </div> <hr style="clear: both;" /> <table border="1" cellpadding="3" cellspacing="0"> <caption style="font-weight: bold;">All Routes</caption> <tr class="header"> <th>Matches Current Request</th> <th>Url</th> <th>Defaults</th> <th>Constraints</th> <th>DataTokens</th> </tr> {2} </table> <hr /> <h3>Current Request Info</h3> <p> AppRelativeCurrentExecutionFilePath is the portion of the request that Routing acts on. </p> <p><strong>AppRelativeCurrentExecutionFilePath</strong>: {3}</p> </div> </div>", new object[] { text3, text10, text4, request.AppRelativeCurrentExecutionFilePath, text11, text })); }
注：RouteDebugger的源码是通过ILSpy反编译的。
结束语
抽出时间去验证路由顺序是因为两个错误引起的：
1.升级vs2013的mvc4解决方案到vs2015后所有的Area路由失效，返回404错误。以为是vs2015对mvc4的支持不够（刚出来是对mvc4是有点问题），就撤销升级返回vs2013了。
2.在vs2013中添加了一个新的Area，排在了以前的所有路由之后，出现404错误。通过RouteDebugger发现是路由的顺序问题，所以想到上面那个问题应该也是顺序问题，不应该是vs2015的缺陷。
希望这篇文章可以帮助你避免遇到同样的问题，觉着有用就推荐一下吧