• ASP.NET MVC自定义视图引擎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());
            }
       }

    启动应用程序浏览/Home/Index 可见效果

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  • 原文地址:https://www.cnblogs.com/rinack/p/5753230.html
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