MVC原理

调用流程，不多阐述，请看下图

下面通过代码执行流程演示

1.浏览器请求：http://localhost/SimpleMvc/Home/Index

2.在Global.asax文件的Application_Start方法中注册路由服务

 protected void Application_Start(object sender, EventArgs e)
        {
            RouteTable.Routes.Add("default", new Route("{controller}/{action}",new SimpleRouteHandler()));
        }

controlleraction会直接映射为路由表中的keyValue键值，方便下一步路

3. 1的url会通过路由表进入IRouteHandler（自定义SimpleRouteHandler）

    public class SimpleRouteHandler:IRouteHandler
    {
        public IHttpHandler GetHttpHandler(RequestContext requestContext)
        {
            return new SimpleHttpHandler(requestContext.RouteData.Values);
        }
    }

这里只是演示mvc的原理，因此只将路由相关的数据传递下去，实际场景中还有很多其他的参数需要映射和传

4.参考上面的实现，我们这里只把路由数据传递给IHttpHandler（自定义SimpleHttpHandler）

   public class SimpleHttpHandler:IHttpHandler
    {
        public SimpleHttpHandler(RouteValueDictionary routeData)
        {
            _routeData = routeData;
        }

        private RouteValueDictionary _routeData;

        public bool IsReusable
        {
            get { throw new NotImplementedException(); }
        }

        /// <summary>
        /// 通过controller，action激活Controller，然后执行Action，返回结果
        /// </summary>
        /// <param name="context"></param>
        public void ProcessRequest(HttpContext context)
        {
            var model = new SimpleModle();
             model.Controller =_routeData["controller"].ToString();
             model.Action =_routeData["action"].ToString();
           
            var control = ControllerFactory.Instance.GetController(model.Controller);
            if (control!=null)
            {
                var view = control.Excute(model.Action, new object[] { model });
                if (view!=null)
                {
                    context.Response.Write(view);
                    return;
                }
            }
            context.Response.Write("<h3>不支持该请求</h3>");
        }
    }

4.1如何激活controller可以参考以下代码

  public class ControllerFactory
    {
        private ControllerFactory()
        {
        }

        static ControllerFactory()
        {
        }

        private const string END = "Controller";

        private static object syn = new object();

        private Dictionary<string, Type> _contrDc = new Dictionary<string, Type>();

        public static readonly ControllerFactory Instance = new ControllerFactory();

        /// <summary>
        /// 根据controller名称返回实例
        /// </summary>
        /// <param name="controllerName"></param>
        /// <returns></returns>
        public IController GetController(string controllerName)
        {
            if (!string.IsNullOrEmpty(controllerName))
            {
                if (!controllerName.EndsWith(END))
                {
                    controllerName += END;
                }

                if (!_contrDc.ContainsKey(controllerName))
                {
                    lock (syn)
                    {
                        if (!_contrDc.ContainsKey(controllerName))
                        {
                            var type = Assembly.GetExecutingAssembly().GetTypes().FirstOrDefault(s => typeof(IController).IsAssignableFrom(s) && string.Equals(s.Name, controllerName, StringComparison.InvariantCultureIgnoreCase));
                            _contrDc.Add(controllerName, type);
                        }
                    }
                }
                if (_contrDc[controllerName] != null)
                {
                    return (IController)Activator.CreateInstance(_contrDc[controllerName]);
                }
            }
            return null;
        }
    }

4.2，controller如何执行action，可以参考一下代码

 public interface IController
    {
        object Excute(string action, object[] parameters);
    }



    public abstract class ControllerBase : IController
    {
        public virtual object Excute(string action,object[] parameters)
        {
            var method = this.GetType().GetMethod(action);
            if (method!=null)
            {
               return method.Invoke(this, parameters);
            }
            return null;
        }

    }



    public class HomeController : IController
    {
        public object Excute(string action, object[] parameters)
        {
            var model = parameters[0] as SimpleModle;
            string content = "参数无效";
            if (model != null)
            {
                content = string.Format("Controller:{0}<br/>Action:{1}", model.Controller, model.Action);
            }
            return new RawContentResult(content);
        }
    }

4.3 简单的Modle

    public class SimpleModle
    {
        public string Controller { get; set; }

        public string Action { get; set; }
    }

4.4 简单的view

  public abstract class ActionResult
    {

    }


  class RawContentResult : ActionResult
    {
        public RawContentResult(string content)
        {
            Content = content;
        }
        public string Content { get; set; }

        public override string ToString()
        {
            return Content;
        }

5.返回结果：