自定义MVC视图引擎ViewEngine 创建Model的专属视图

MVC内置的视图引擎有WebForm view engine和Razor view engine，当然也可以自定义视图引擎ViewEngine。本文想针对某个Model，自定义该Model的专属视图。

□ 思路

1、控制器方法返回ActionResult是一个抽象类
2、ActionResult的其中一个子类ViewResult，正是她使用IView实例最终渲染出视图
3、需要自定义IView
4、IViewEngine管理着IView，同时也需要自定义IViewEngine
5、自定义IViewEngine是需要全局注册的

□ IView接口

public interface IView

{

    void Render(System.Web.Mvc.ViewContext viewContext, System.IO.TextWriter writer)

}

第一个参数ViewContext包含了需要被渲染的信息，被传递到前台的强类型Model也包含在其中。
第二个参数TextWriter可以帮助我们写出想要的html格式。

□ IViewEngine接口

public interface IViewEngine

{

    System.Web.Mvc.ViewEngineResult FindPartialView(System.Web.Mvc.ControllerContext controllerContext, string partialViewName, bool useCache);

    System.Web.Mvc.ViewEngineResult FindView(System.Web.Mvc.ControllerContext controllerContext, string viewName, string masterName, bool useCache);

    void ReleaseView(System.Web.Mvc.ControllerContext controllerContext, System.Web.Mvc.IView view);

}

FindPartialView:在当前控制器上下文ControllerContext中找到部分视图。
FindView：在当前控制器上下文ControllerContext中找到视图。

ReleaseView：释放当前控制器上下文ControllerContext中的视图。

模拟一个Model和数据服务类

   public class Student

    {

        public int Id { get; set; }

        public string Name { get; set; }

        public int Score { get; set; }

    }

    public class DataAccess

    {

        List<Student> students = new List<Student>();

        public DataAccess()

        {

            for (int i = 0; i < 10; i++)

            {

                students.Add(new Student

                {

                    Id = i + 1,

                    Name = "Name" + Convert.ToString(i+1),

                    Score = i + 80

                });

            }

        }

        public List<Student> GetStudents()

        {

            return students;

        }

    }

实现IView接口，自定义输出html格式

using System.Collections.Generic;

using System.Web.Mvc;

using CustomViewEngine.Models;

namespace CustomViewEngine.Extension

{

    public class StudentView : IView

    {

        public void Render(ViewContext viewContext, System.IO.TextWriter writer)

        {

            //从视图上下文ViewContext中拿到model

            var model = viewContext.ViewData.Model;

            var students = model as List<Student>;

            //自定义输出视图的html格式

            writer.Write("<table border=1><tr><th>编号</th><th>名称</th><th>分数</th></tr>");

            foreach (Student stu in students)

            {

                writer.Write("<tr><td>" + stu.Id + "</td><td>" + stu.Name + "</td><td>" + stu.Score + "</td></tr>");

            }

            writer.Write("</table>");

        }

    }

}

实现IViewEngine，返回自定义IView

using System;

using System.Web.Mvc;

namespace CustomViewEngine.Extension

{

    public class StudentViewEngine : IViewEngine

    {

        public ViewEngineResult FindPartialView(ControllerContext controllerContext, string partialViewName, bool useCache)

        {

            throw new System.NotImplementedException();

        }

        public ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache)

        {

            if (viewName == "StudentView")

            {

                return new ViewEngineResult(new StudentView(), this);

            }

            else

            {

                return new ViewEngineResult(new String[]{"针对Student的视图还没创建！"});

            }

        }

        public void ReleaseView(ControllerContext controllerContext, IView view)

        {

        }

    }

}

HomeController

using System.Web.Mvc;

using CustomViewEngine.Models;

namespace CustomViewEngine.Controllers

{

    public class HomeController : Controller

    {

        public ActionResult Index()

        {

            var students = new DataAccess().GetStudents();

            ViewData.Model = students;

            return View("StudentView");

        }

    }

}

全局注册

    public class MvcApplication : System.Web.HttpApplication

    {

        protected void Application_Start()

        {

            AreaRegistration.RegisterAllAreas();

            WebApiConfig.Register(GlobalConfiguration.Configuration);

            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);

            RouteConfig.RegisterRoutes(RouteTable.Routes);

            BundleConfig.RegisterBundles(BundleTable.Bundles);

            ViewEngines.Engines.Add(new StudentViewEngine());

        }

    }

浏览/Home/Index效果：