C#高级编程笔记2016年10月26日MVC入门Controller

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1、MVC的定义：

Models: Classes that represent the data of the application and that use validation logic to enforce business rules for that data.
Views: Template files that your application uses to dynamically generate HTML responses.
Controllers: Classes that handle incoming browser requests, retrieve model data, and then specify view templates that return a response to the browser.

2、MVC的路由调用：（在 App_Start中的RouteConfig.cs 中定义了路由调用的基本格式）

RouteConfig.cs

using System.Web.Mvc;
using System.Web.Routing;
 
namespace MvcWebApplication
{
    public class RouteConfig
    {
        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 }//当url中无输入时，默认到Home 控制器中的Index  Action 里面
            );
        }
    }
}

ASP.NET MVC invokes different controller classes (and different action methods within them) depending on the incoming URL. The default URL routing logic used by ASP.NET MVC uses a format like this to determine what code to invoke:

/ [Controller] / [ActionName] / [Parameters]

When you run the application and don't supply any URL segments, it defaults to the "Home" controller and the "Index" action method specified in the defaults section of the code above.

　　[Controller]

The first part of the URL determines the controller class to execute. So /HelloWorld maps to the HelloWorldController class.

[ActionName]

　　The second part of the URL determines the action method on the class to execute. So /HelloWorld/Index would cause the Index method of the HelloWorldController class to execute. Notice that we only had to browse to /HelloWorld and the Index method was used by default. This is because a method named Index is the default method that will be called on a controller if one is not explicitly specified.

[Parameters]

　　The third part of the URL segment ( Parameters) is for route data. We'll see route data later on in this tutorial.

Browse to http://localhost:xxxx/HelloWorld/Welcome. The Welcome method runs and returns the string "This is the Welcome action method...". The default MVC mapping is /[Controller]/[ActionName]/[Parameters]. For this URL, the controller is HelloWorld and Welcome is the action method. You haven't used the [Parameters] part of the URL yet.

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 }
    );}

3、HttpUtility：System.Web.HttpUtility

提供用于在处理Web请求时编码和解码 URL 的方法，此类不能被继承。

4、/ [Controller] / [ActionName] / [Parameters] 的理解

Let's modify the example slightly so that you can pass some parameter information from the URL to the controller (for example, /HelloWorld/Welcome?name=Scott&numtimes=4). Change your Welcome method to include two parameters as shown below. Note that the code

public string Welcome(string name, int numTimes = 1) {
return HttpUtility.HtmlEncode("Hello " + name + ", NumTimes is: " + numTimes);}

Run your application and browse to the example URL (http://localhost:xxxx/HelloWorld/Welcome?name=Scott&numtimes=4). You can try different values for name and numtimes in the URL. The ASP.NET MVC model binding system automatically maps the named parameters from the query string in the address bar to parameters in your method.

Replace the Welcome method with the following code:

public string Welcome(string name, int ID = 1){
    return HttpUtility.HtmlEncode("Hello " + name + ", ID: " + ID);}

Run the application and enter the following URL: http://localhost:xxx/HelloWorld/Welcome/3?name=Rick

##为什么这时的“ 3 ” 能够被识别，而不用输入 "gender = 3" 呢？

这是路由中的源码：

1 public static void RegisterRoutes(RouteCollection routes){
2     routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
3 
4     routes.MapRoute(
5         name: "Default",
6         url: "{controller}/{action}/{id}",
7         defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
8     );}

This time the third URL segment matched the route parameter ID. The Welcome action method contains a parameter (ID) that matched the URL specification in the RegisterRoutes method.

在 url 中有参数 id , 于是MVC 便会自动匹配。

In ASP.NET MVC applications, it's more typical to pass in parameters as route data (like we did with ID above) than passing them as query strings. You could also add a route to pass both the name and numtimes in parameters as route data in the URL. In the App_Start\RouteConfig.cs file, add the "Hello" route:

public class RouteConfig{
   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 }
      );
 
      routes.MapRoute(
           name: "Hello",
           url: "{controller}/{action}/{name}/{id}"
       );
   }}