Asp.Net Mvc 路由机制

先说一下基本的路由规则原则。基本的路由规则是从特殊到一般排列，也就是最特殊（非主流）的规则在最前面，最一般（万金油）的规则排在最后。这是因为匹配路由规则也是照着这个顺序的。如果写反了，那么即便你路由规则写对了那照样坐等404.

XD 首先说URL的构造。其实这个也谈不上构造，只是语法特性吧。

URL构造

命名参数规范+匿名对象

routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Perpon", action = "Index", id = UrlParameter.Optional }
    //constraints: new { controller=@"^\w+$", id=@"^\d+$" } //约束
    //namespaces: new string[] { "Mvc4.Models" } //控制器命名空间的约束
);

构造路由然后添加

Route myRoute = new Route("{controller}/{action}/{id}", new MvcRouteHandler());
routes.Add(myRoute);

直接方法重载+匿名对象

routes.MapRoute(
　　"Default1",//name: "Default1",
　　"{controller}/{action}/{id}",//url: "{controller}/{action}/{id}",
　　new { controller = "Test", action = "Index", id = UrlParameter.Optional }//defaults: new { controller = "Perpon", action = "Index", id = UrlParameter.Optional }
);

路由规则

1.默认路由(MVC自带)

routes.MapRoute(
    "Default",//路由名称，不可重复
    "{controller}/{action}/{id}",//带有参数的 URL
    new{ controller = "Home", action = "Index", id = UrlParameter.Optional } //参数默认值 (UrlParameter.Optional-可选的意思) 
);

2.静态URL段

routes.MapRoute(
    "ShopSchema2",
    "Shop/OldAction",
    new { controller = "Home", action = "Index"});

routes.MapRoute(
    "ShopSchema",
    "Shop/{action}",
    new {controller = "Home"}
);

routes.MapRoute(
    "ShopSchema2",
    "Shop/OldAction.js",
    new{ controller = "Home", action = "Index"}
);

没有占位符路由就是现成的写死的。

比如这样写然后去访问http://localhost:XXX/Shop/OldAction.js，response也是完全没问题的。 controller , action , area这三个保留字就别设静态变量里面了。

3.自定义常规变量URL段

routes.MapRoute(
    "MyRoute2",
    "{controller}/{action}/{id}",
    new{ controller = "Home", action = "Index", id = "DefaultId"}
);

这种情况如果访问 /Home/Index 的话，因为第三段（id）没有值，根据路由规则这个参数会被设为DefaultId

这个用viewbag给title赋值就能很明显看出

ViewBag.Title = RouteData.Values["id"];

图不贴了，结果是标题显示为DefaultId。注意要在控制器里面赋值，在视图赋值没法编译的。

4.再述默认路由

然后再回到默认路由。 UrlParameter.Optional这个叫可选URL段.路由里没有这个参数的话id为null。照原文大致说法，这个可选URL段能用来实现一个关注点的分离。刚才在路由里直接设定参数默认值其实不是很好。照我的理解，实际参数是用户发来的，我们做的只是定义形式参数名。但是，如果硬要给参数赋默认值的话，建议用语法糖写到action参数里面。比如：

public ActionResult Index(string id = "abcd")
{
    ViewBag.Title = RouteData.Values["id"];
    returnView();
}

5.可变长度路由。

routes.MapRoute(
    "MyRoute",
    "{controller}/{action}/{id}/{*catchall}",
    new{ controller = "Home", action = "Index", id = UrlParameter.Optional }
);

在这里id和最后一段都是可变的，所以 /Home/Index/dabdafdaf 等效于 /Home/Index//abcdefdjldfiaeahfoeiho 等效于 /Home/Index/All/Delete/Perm/.....

6.跨命名空间路由

这个提醒一下记得引用命名空间，开启IIS网站不然就是404。这个非常非主流，不建议瞎搞。

routes.MapRoute(
    "MyRoute",
    "{controller}/{action}/{id}/{*catchall}",
    new{ controller = "Home", action = "Index", id = UrlParameter.Optional },
    new[] {"URLsAndRoutes.AdditionalControllers","UrlsAndRoutes.Controllers"}
);

但是这样写的话数组排名不分先后的，如果有多个匹配的路由会报错。然后作者提出了一种改进写法。

routes.MapRoute(
    "AddContollerRoute",
    "Home/{action}/{id}/{*catchall}",
    new{ controller = "Home", action = "Index", id = UrlParameter.Optional },
    new[] { "URLsAndRoutes.AdditionalControllers"}
);

routes.MapRoute(
    "MyRoute",
    "{controller}/{action}/{id}/{*catchall}",
    new{ controller = "Home", action = "Index", id = UrlParameter.Optional },
    new[] { "URLsAndRoutes.Controllers"}
);

这样第一个URL段不是Home的都交给第二个处理最后还可以设定这个路由找不到的话就不给后面的路由留后路啦，也就不再往下找啦。

Route myRoute = routes.MapRoute("AddContollerRoute", "Home/{action}/{id}/{*catchall}", new{ controller = "Home", action = "Index", id = UrlParameter.Optional }, new[] { "URLsAndRoutes.AdditionalControllers"}); 
myRoute.DataTokens["UseNamespaceFallback"] = false;

7.正则表达式匹配路由

routes.MapRoute(
    "MyRoute",
    "{controller}/{action}/{id}/{*catchall}",
    new{ controller = "Home", action = "Index", id = UrlParameter.Optional },
    new{ controller = "^H.*"},
    new[] {"URLsAndRoutes.Controllers"}
);

约束多个URL

routes.MapRoute(
    "MyRoute",
    "{controller}/{action}/{id}/{*catchall}",
    new{ controller = "Home", action = "Index", id = UrlParameter.Optional },
    new{ controller = "^H.*", action = "^Index$|^About$"},
    new[] { "URLsAndRoutes.Controllers"}
);

8.指定请求方法

routes.MapRoute(
    "MyRoute",
    "{controller}/{action}/{id}/{*catchall}",
    new{ controller = "Home", action = "Index", id =    UrlParameter.Optional },
    new{ controller = "^H.*", action = "Index|About", httpMethod    = newHttpMethodConstraint("GET")},
    new[]{ "URLsAndRoutes.Controllers"}
);

9. WebForm支持

routes.MapPageRoute("","","~/Default.aspx");

routes.MapPageRoute(
    "list",
    "Items/{action}",
    "~/Items/list.aspx",
    false,
    newRouteValueDictionary{{ "action","all" }}
);

routes.MapPageRoute(
    "show",
    "Show/{action}",
    "~/show.aspx",
    false,
    newRouteValueDictionary{ { "action","all" }}
);

routes.MapPageRoute(
    "edit",
    "Edit/{id}",
    "~/edit.aspx",
    false,
    new RouteValueDictionary{ { "id","1" }},         
    new RouteValueDictionary{ { "id",@"\d+" }}
);

10.MVC5的RouteAttribute

首先要在路由注册方法那里

//启用路由特性映射
routes.MapMvcAttributeRoutes();

这样

[Route("Login")]

route特性才有效.该特性有好几个重载.还有路由约束啊,顺序啊,路由名之类的.

其他的还有路由前缀,路由默认值

[RoutePrefix("reviews")]
[Route("{action=index}")]
publicclassReviewsController : Controller
{
}

路由构造

//eg: /users/5
[Route("users/{id:int}"]
public ActionResult GetUserById(int id)
{ }

//eg: users/ken
[Route("users/{name}"]
public ActionResult GetUserByName(string name)
{ }

参数限制

//eg: /users/5

//but not /users/10000000000 because it is larger than int.MaxValue,

//and not /users/0 because of the min(1) constraint.

[Route("users/{id:int:min(1)}")]
public ActionResult GetUserById(int id)
{  }

Constraint	Description	Example
alpha	Matches uppercase or lowercase Latin alphabet characters (a-z, A-Z)	{x:alpha}
bool	Matches a Boolean value.	{x:bool}
datetime	Matches a DateTime value.	{x:datetime}
decimal	Matches a decimal value.	{x:decimal}
double	Matches a 64-bit floating-point value.	{x:double}
float	Matches a 32-bit floating-point value.	{x:float}
guid	Matches a GUID value.	{x:guid}
int	Matches a 32-bit integer value.	{x:int}
length	Matches a string with the specified length or within a specified range of lengths.	{x:length(6)} {x:length(1,20)}
long	Matches a 64-bit integer value.	{x:long}
max	Matches an integer with a maximum value.	{x:max(10)}
maxlength	Matches a string with a maximum length.	{x:maxlength(10)}
min	Matches an integer with a minimum value.	{x:min(10)}
minlength	Matches a string with a minimum length.	{x:minlength(10)}
range	Matches an integer within a range of values.	{x:range(10,50)}
regex	Matches a regular expression.	{x:regex(^\d{3}-\d{3}-\d{4}$)}

对我来说,这样的好处是分散了路由规则的定义.有人喜欢集中,我个人比较喜欢这种灵活的处理.因为这个action定义好后,我不需要跑到配置那里定义对应的路由规则

11.访问本地文档

routes.RouteExistingFiles = true;
routes.MapRoute(
    "DiskFile",
    "Content/StaticContent.html",
    new{ controller = "Customer", action = "List"}
);

浏览网站，以开启 IIS Express，然后点显示所有应用程序-点击网站名称-配置（applicationhost.config）-搜索UrlRoutingModule节点

<add name="UrlRoutingModule-4.0" type="System.Web.Routing.UrlRoutingModule" preCondition="managedHandler,runtimeVersionv4.0"/>

把这个节点里的preCondition删除，变成

<add name="UrlRoutingModule-4.0" type="System.Web.Routing.UrlRoutingModule" preCondition="" />

12.直接访问本地资源，绕过了路由系统

routes.IgnoreRoute("Content/{filename}.html");

文件名还可以用 {filename}占位符。

IgnoreRoute方法是RouteCollection里面StopRoutingHandler类的一个实例。路由系统通过硬-编码识别这个Handler。如果这个规则匹配的话，后面的规则都无效了。这也就是默认的路由里面routes.IgnoreRoute("{resource}.axd/{*pathInfo}");写最前面的原因。

路由测试代码：