zoukankan      html  css  js  c++  java
  • 1. View

    1. View

    最常用的一种,用于返回一个 "标准" 页面。

    protected internal virtual ViewResult View(string viewName, string masterName, object model)
    {
      if (model != null)
      {
        base.ViewData.Model = model;
      }

      return new ViewResult
      {
        ViewName = viewName,
        MasterName = masterName,
        ViewData = base.ViewData,
        TempData = base.TempData
      };
    }

    public class ViewResult : ViewResultBase
    {
      protected override ViewEngineResult FindView(ControllerContext context)
      {
        ViewEngineResult result = ViewEngineCollection.FindView(context, ViewName, MasterName);

        if (result.View != null)
        {
          return result;
        }

        ...
      }
    }


    这个页面默认是 ViewPage,也可以是我们自己定义的其它模板引擎页面。

    MVC 还提供了强类型的 ViewPage<TModel>。

    public class User
    {
      public string Name { get; set; }
      public int Age { get; set; }
    }

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        ViewData["message"] = "Hello, World!";
        var model = new User { Name = "Tom", Age = 13 };

        return View(model);
      }
    }


    Index.aspx

    <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<Learn.MVC.Controllers.User>" %>

    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
      <title>Index</title>
    </head>
    <body>
      Name: <%= Model.Name %>; Age: <%= Model.Age %>
    </body>
    </html>


    在 WebForm 时代,我们就已经习惯了将一个页面分解成多个 UserControl,现在我们依然可以这么做。htmlHelper 专门提供了 RenderPartial 扩展方法,从当前视图目录(Views\xxx)下载入 .ascx 页面。

    public static class RenderPartialExtensions
    {
      public static void RenderPartial(this HtmlHelper htmlHelper, partialViewName, model, viewData)
      {
        htmlHelper.RenderPartialInternal(partialViewName, viewData, model, ViewEngines.Engines);
      }
    }

    public class HtmlHelper
    {
      internal virtual void RenderPartialInternal(string partialViewName, ViewDataDictionary viewData,
        object model, ViewEngineCollection viewEngineCollection)
      {
        ...

        ViewDataDictionary newViewData = null;

        if (model == null)
        {
          if (viewData == null)
            newViewData = new ViewDataDictionary(ViewData);
          else
            newViewData = new ViewDataDictionary(viewData);
        }
        else
        {
          if (viewData == null)
            newViewData = new ViewDataDictionary(model);
          else
            newViewData = new ViewDataDictionary(viewData) { Model = model };
        }

        ViewContext newViewContext = new ViewContext(ViewContext, ViewContext.View,
          newViewData, ViewContext.TempData);

        IView view = FindPartialView(newViewContext, partialViewName, viewEngineCollection);

        view.Render(newViewContext, ViewContext.HttpContext.Response.Output);
      }

      internal static IView FindPartialView(viewContext, partialViewName, viewEngineCollection)
      {
        ViewEngineResult result = viewEngineCollection.FindPartialView(viewContext, partialViewName);

        if (result.View != null)
        {
          return result.View;
        }

        ...
      }
    }


    RenderPartialInternal 调用 FindParitialView 从视图引擎中载入 .ascx,同时将当前的环境参数传递给它。也就是说 RenderPartial 只是一种视图级别的行为,并不会再次触发 Controller Action 操作,这点要和 Controller.PartialView() 区别开来。

    Index.aspx

    <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<Learn.MVC.Controllers.User>" %>

    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
      <title>Index</title>
    </head>
    <body>
      Name: <%= Model.Name %>; Age: <%= Model.Age %>
      <br />
      <% Html.RenderPartial("Part"); %>
    </body>
    </html>


    Part.ascx

    <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<Learn.MVC.Controllers.User>" %>

    <%= ViewData["message"] %>
    <br />
    <%= Model.Name %>


    2. Content

    Content 用于输出(Response.Write) "静态" 片段。

    protected internal virtual ContentResult Content(content, contentType, contentEncoding)
    {
      return new ContentResult
      {
        Content = content,
        ContentType = contentType,
        ContentEncoding = contentEncoding
      };
    }

    public class ContentResult : ActionResult
    {
      public string Content { get; set; }
        
      public override void ExecuteResult(ControllerContext context)
      {
        ...

        HttpResponseBase response = context.HttpContext.Response;

        if (!String.IsNullOrEmpty(ContentType))
        {
          response.ContentType = ContentType;
        }
        if (ContentEncoding != null)
        {
          response.ContentEncoding = ContentEncoding;
        }
        if (Content != null)
        {
          response.Write(Content);
        }
      }
    }


    看看和 jQuery 的配合使用。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return View();
      }

      public ActionResult Part()
      {
        return Content("<a href=\"http://www.rainsts.net\">Q.yuhen</a>");
      }
    }


    Index.aspx

    <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>

    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
      <title>Index</title>
      <script src="http://www.cnblogs.com/Scripts/jquery-1.3.1.min.js" type="text/javascript"></script>
      <script type="text/javascript">
        $(function()
        {
          $("#div1").load("/test/part");
        });
      </script>
    </head>
    <body>
      <div id="div1">
      </div>
    </body>
    </html>


    3. PartialView

    Controller.PartialView() 和 HtmlHelper.RenderPartial() 的不同之处在于前者是再次执行 ActionInvoke 并返回一个 ActionResult 结果,后者只是使用现有的 ViewContext 显示一个视图片段。而与 Controller.Content() 的区别是 PartialView() 使用视图引擎输出一个 "动态" 的 ascx 结果。

    protected internal virtual PartialViewResult PartialView(string viewName, object model)
    {
      if (model != null)
      {
        ViewData.Model = model;
      }

      return new PartialViewResult
      {
        ViewName = viewName,
        ViewData = ViewData,
        TempData = TempData
      };
    }

    public class PartialViewResult : ViewResultBase
    {
      protected override ViewEngineResult FindView(ControllerContext context)
      {
        ViewEngineResult result = ViewEngineCollection.FindPartialView(context, ViewName);

        if (result.View != null)
        {
          return result;
        }
        
        ...
      }
    }


    和 Content() 一样,我们通常将其和 jQuery 等 Ajax 框架配合使用。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return View();
      }

      public ActionResult Part()
      {
        ViewData["time"] = DateTime.Now;
        var model = new User { Name = "Tom", Age = 13 };

        return PartialView(model);
      }
    }


    Index.aspx

    <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>

    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
      <title>Index</title>
      <script src="http://www.cnblogs.com/Scripts/jquery-1.3.1.min.js" type="text/javascript"></script>
      <script type="text/javascript">
        $(function()
        {
          $("#div1").load("/test/part");
        });
      </script>
    </head>
    <body>
      <div id="div1">
      </div>
    </body>
    </html>


    Part.ascx

    <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<Learn.MVC.Controllers.User>" %>

    <%= ViewData["time"] %> <br />
    <%= Model.Name %>; <%= Model.Age %>


    4. Redirect / RedirectToAction / RedirectToRoute

    Controller 提供了几种方式,让我们在不同的 Action 之间进行跳转。

    public class MvcApplication : System.Web.HttpApplication
    {
      public static void RegisterRoutes(RouteCollection routes)
      {
        ...

        routes.MapRoute
        (
          "Test2",
          "Test/T2/{name}/{age}",
          new { controller = "Test", action = "T2", name = "", age = 0 }
        );

        ...
      }
    }


    方法1:

    Redirect() 直接用 Response.Redirect() 完成 url 跳转。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return Redirect("/Test/T2/Tom/23");
      }

      public ActionResult T2(User user)
      {
        return Content(user.Name);
      }
    }


    相关细节:

    protected internal virtual RedirectResult Redirect(string url)
    {
      ...
      return new RedirectResult(url);
    }

    public class RedirectResult : ActionResult
    {
      public override void ExecuteResult(ControllerContext context)
      {
        ...

        string destinationUrl = UrlHelper.Content(Url, context.HttpContext);
        context.HttpContext.Response.Redirect(destinationUrl, false /* endResponse */);
      }
    }


    方法2:

    RedirectToAction() 直接使用 Action Name 进行跳转。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return RedirectToAction("T2", new { name = "Tom", age = 23 });
      }

      public ActionResult T2(User user)
      {
        return Content(user.Name);
      }
    }


    如果目标 Action 不在当前 Controller 类,则可以指定目标 Controller Name。

    return RedirectToAction("T2", new { controller="Test2", name = "Tom", age = 23 });


    相关细节:

    protected internal virtual RedirectToRouteResult RedirectToAction(string actionName,
      string controllerName, RouteValueDictionary routeValues)
    {
      RouteValueDictionary mergedRouteValues;

      if (RouteData == null)
      {
        mergedRouteValues = RouteValuesHelpers.MergeRouteValues(actionName,
          controllerName, null, routeValues, true /* includeImplicitMvcValues */);
      }
      else
      {
        mergedRouteValues = RouteValuesHelpers.MergeRouteValues(actionName,
          controllerName, RouteData.Values, routeValues, true /* includeImplicitMvcValues */);
      }

      return new RedirectToRouteResult(mergedRouteValues);
    }

    public class RedirectToRouteResult : ActionResult
    {
      public override void ExecuteResult(ControllerContext context)
      {
        ...

        string destinationUrl = UrlHelper.GenerateUrl(RouteName, null /* actionName */,
          null /* controllerName */, RouteValues, Routes, context.RequestContext,
          false /* includeImplicitMvcValues */);

        ...
        context.HttpContext.Response.Redirect(destinationUrl, false /* endResponse */);
      }
    }


    可以看到 RedirectToRouteResult.ExecuteResult 中使用 Route 相关信息拼接成目标 Url 后进行跳转。

    方法3:

    RedirectToRoute() 则是直接用 MapRoute 时定义的 Route Name 进行跳转。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return RedirectToRoute("Test2", new { name = "Tom", age = 23 });
      }
    }


    相关细节:

    protected internal virtual RedirectToRouteResult RedirectToRoute(string routeName, RouteValueDictionary routeValues)
    {
      return new RedirectToRouteResult(routeName, RouteValuesHelpers.GetRouteValues(routeValues));
    }


    执行过程和 RedirectToAction() 相同。

    5. Json

    Json() 在编写 Ajax 时非常有用,可以将 Entity 等对象序列化成 JSON 格式供 Javascript 使用。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return View();
      }

      public ActionResult GetUser(string name)
      {
        var user = new User { Name = name, Age = 23 };
        return Json(user);
      }
    }


    Index.aspx

    <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>

    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
      <title>Index</title>
      <script src="http://www.cnblogs.com/Scripts/jquery-1.3.1.min.js" type="text/javascript"></script>
      <script type="text/javascript">
        $(function()
        {
          $("#btnTest").click(function()
          {
            $.getJSON
            (
              "/Test/GetUser",
              { name: "Tom" },
              function(json)
              {
                alert(json.Name + ";" + json.Age);
              }
            );
          });
        });
      </script>
    </head>
    <body>
      <input type="button" id="btnTest" value="Test" />
    </body>
    </html>


    很好用,不是吗?看看相关细节。

    protected internal virtual JsonResult Json(object data, string contentType, Encoding contentEncoding)
    {
      return new JsonResult
      {
        Data = data,
        ContentType = contentType,
        ContentEncoding = contentEncoding
      };
    }

    public class JsonResult : ActionResult
    {
      public override void ExecuteResult(ControllerContext context)
      {
        ...

        if (Data != null)
        {
          JavaScriptSerializer serializer = new JavaScriptSerializer();
          response.Write(serializer.Serialize(Data));
        }
      }
    }


    使用 System.Web.Script.Serialization.JavaScriptSerializer 完成 JSON 序列化操作,也就是说我们还可以用 ScriptIgnoreAttribute 排除某些属性。

    6. Javascript

    某些时候,我们需要根据一些逻辑判断来载入执行不同的 Javascript 代码。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return View();
      }

      public ActionResult GetJs(int id)
      {
        switch (id)
        {
          case 1:
            return JavaScript("alert('Hello, C#!');");      
          case 2:
            return JavaScript("alert('Hello, MVC!');");      
          default:
            return null;
        }
      }
    }


    Index.aspx

    <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>

    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
      <title>Index</title>
      <script src="http://www.cnblogs.com/Scripts/jquery-1.3.1.min.js" type="text/javascript"></script>
      <script type="text/javascript">
        $(function()
        {
          $("#btnTest").click(function()
          {
            var id = $("#txtId").val();
            $.getScript("/Test/GetJs/" + id);
          });
        });
      </script>
    </head>
    <body>
      <input type="text" id="txtId" value="1" />
      <input type="button" id="btnTest" value="Test" />
    </body>
    </html>


    只是这种做法,似乎将 View 和 Controller 的耦合加大了…… 还不如直接用 Javascript 来处理这些。

    protected internal virtual JavaScriptResult JavaScript(string script)
    {
      return new JavaScriptResult { Script = script };
    }

    public class JavaScriptResult : ActionResult
    {
      public override void ExecuteResult(ControllerContext context)
      {
        ...

        HttpResponseBase response = context.HttpContext.Response;
        response.ContentType = "application/x-javascript";

        if (Script != null)
        {
          response.Write(Script);
        }
      }
    }


    7. File (Download / Upload)

    File() 提供了 Download 功能。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return View();
      }

      public ActionResult Download(int id)
      {
        var filename = String.Format("~/Content/Download/{0}.rar", id);
        var fileDownloadName = String.Format("{0}.rar", id);

        return File(filename, "application/octet-stream", fileDownloadName);
      }
    }


    当我们在浏览器请求 "/Test/Download/1" 是就会打开下载窗口,同时给出了保存文件名。

    protected internal virtual FileContentResult File(byte[] fileContents, contentType, fileDownloadName)
    {
      return new FileContentResult(fileContents, contentType) { FileDownloadName = fileDownloadName };
    }

    public abstract class FileResult : ActionResult
    {
      public override void ExecuteResult(ControllerContext context)
      {
        ...
        HttpResponseBase response = context.HttpContext.Response;
        response.ContentType = ContentType;
        ...
        WriteFile(response);
      }

      protected abstract void WriteFile(HttpResponseBase response);
    }

    public class FileContentResult : FileResult
    {
      protected override void WriteFile(HttpResponseBase response)
      {
        response.OutputStream.Write(FileContents, 0, FileContents.Length);
      }
    }


    文件上传是另一个常用的 Web 应用。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return View();
      }

      public ActionResult Upload(HttpPostedFileBase file)
      {
        var filename = Server.MapPath("~/Content/Upload/" + Path.GetFileName(file.FileName));

        file.SaveAs(filename);
        return null;
      }
    }


    Index.aspx

    <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>

    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
      <title>Index</title>
    </head>
    <body>
      <form action="/Test/Upload" enctype="multipart/form-data" method="post">
        <input type="file" name="file" />
        <input type="submit" name="upload" />
      </form>
    </body>
    </html>


    MVC 提供了一个 HttpPostedFileBaseModelBinder 将 Request.Files 的信息直接映射给 Action 同名参数。

    public class HttpPostedFileBaseModelBinder : IModelBinder
    {
      public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
      {
        ...

        HttpPostedFileBase theFile = controllerContext.HttpContext.Request.Files[bindingContext.ModelName];

        // case 1: there was no <input type="file" ... /> element in the post
        if (theFile == null)
        {
          return null;
        }

        // case 2: there was an <input type="file" ... /> element in the post, but it was left blank
        if (theFile.ContentLength == 0 && String.IsNullOrEmpty(theFile.FileName))
        {
          return null;
        }

        // case 3: the file was posted
        return theFile;
      }
    }


    看看一次上传多个文件的演示。

    public class TestController : Controller
    {
      public ActionResult Index()
      {
        return View();
      }

      public ActionResult Upload(HttpPostedFileBase file1, HttpPostedFileBase file2)
      {
        var html = String.Format("{0}:{1}<br />{2}:{3}",
          file1.FileName, file1.InputStream.Length,
          file2.FileName, file2.InputStream.Length);

        return Content(html);
      }
    }


    Index.aspx

    <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>

    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
      <title>Index</title>
    </head>
    <body>
      <form action="/Test/Upload" enctype="multipart/form-data" method="post">
        <input type="file" name="file1" />
        <input type="file" name="file2" />
        <input type="submit" name="upload" />
      </form>
    </body>
    </html>
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  • 原文地址:https://www.cnblogs.com/dudu837/p/1467299.html
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