下面是我为ASP编写的一个类。NETCore RC2。我使用它，所以我可以生成html电子邮件使用Razor。

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Abstractions;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewEngines;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Routing;
using System.IO;
using System.Threading.Tasks;

namespace cloudscribe.Web.Common.Razor
{
    /// <summary>
    /// the goal of this class is to provide an easy way to produce an html string using 
    /// Razor templates and models, for use in generating html email.
    /// </summary>
    public class ViewRenderer
    {
        public ViewRenderer(
            ICompositeViewEngine viewEngine,
            ITempDataProvider tempDataProvider,
            IHttpContextAccessor contextAccesor)
        {
            this.viewEngine = viewEngine;
            this.tempDataProvider = tempDataProvider;
            this.contextAccesor = contextAccesor;
        }

        private ICompositeViewEngine viewEngine;
        private ITempDataProvider tempDataProvider;
        private IHttpContextAccessor contextAccesor;

        public async Task<string> RenderViewAsString<TModel>(string viewName, TModel model)
        {

            var viewData = new ViewDataDictionary<TModel>(
                        metadataProvider: new EmptyModelMetadataProvider(),
                        modelState: new ModelStateDictionary())
            {
                Model = model
            };

            var actionContext = new ActionContext(contextAccesor.HttpContext, new RouteData(), new ActionDescriptor());
            var tempData = new TempDataDictionary(contextAccesor.HttpContext, tempDataProvider);

            using (StringWriter output = new StringWriter())
            {

                ViewEngineResult viewResult = viewEngine.FindView(actionContext, viewName, true);

                ViewContext viewContext = new ViewContext(
                    actionContext,
                    viewResult.View,
                    viewData,
                    tempData,
                    output,
                    new HtmlHelperOptions()
                );

                await viewResult.View.RenderAsync(viewContext);

                return output.GetStringBuilder().ToString();
            }
        }
    }
}

如果你想完全放弃MVC，从而避免HttpContext的混乱…

using RazorEngine;
using RazorEngine.Templating; // For extension methods.

string razorText = System.IO.File.ReadAllText(razorTemplateFileLocation);
string emailBody = Engine.Razor.RunCompile(razorText, "templateKey", typeof(Model), model);

这里使用了非常棒的开源Razor Engine: https://github.com/Antaris/RazorEngine

我发现了一个新的解决方案，可以将视图呈现为字符串，而不必与当前HttpContext的Response流(它不允许您更改响应的ContentType或其他报头)混淆。

基本上，你所要做的就是为视图创建一个伪HttpContext来渲染它自己:

/// <summary>Renders a view to string.</summary>
public static string RenderViewToString(this Controller controller,
                                        string viewName, object viewData) {
    //Create memory writer
    var sb = new StringBuilder();
    var memWriter = new StringWriter(sb);

    //Create fake http context to render the view
    var fakeResponse = new HttpResponse(memWriter);
    var fakeContext = new HttpContext(HttpContext.Current.Request, fakeResponse);
    var fakeControllerContext = new ControllerContext(
        new HttpContextWrapper(fakeContext),
        controller.ControllerContext.RouteData,
        controller.ControllerContext.Controller);

    var oldContext = HttpContext.Current;
    HttpContext.Current = fakeContext;

    //Use HtmlHelper to render partial view to fake context
    var html = new HtmlHelper(new ViewContext(fakeControllerContext,
        new FakeView(), new ViewDataDictionary(), new TempDataDictionary()),
        new ViewPage());
    html.RenderPartial(viewName, viewData);

    //Restore context
    HttpContext.Current = oldContext;    

    //Flush memory and return output
    memWriter.Flush();
    return sb.ToString();
}

/// <summary>Fake IView implementation used to instantiate an HtmlHelper.</summary>
public class FakeView : IView {
    #region IView Members

    public void Render(ViewContext viewContext, System.IO.TextWriter writer) {
        throw new NotImplementedException();
    }

    #endregion
}

这适用于ASP。NET MVC 1.0，以及ContentResult, JsonResult等(改变原始HttpResponse上的报头不会抛出“发送HTTP报头后服务器无法设置内容类型”异常)。

更新:在ASP。NET MVC 2.0 RC，代码有一点变化，因为我们必须传入用于将视图写入ViewContext的StringWriter:

//...

//Use HtmlHelper to render partial view to fake context
var html = new HtmlHelper(
    new ViewContext(fakeControllerContext, new FakeView(),
        new ViewDataDictionary(), new TempDataDictionary(), memWriter),
    new ViewPage());
html.RenderPartial(viewName, viewData);

//...

为了在服务层中呈现一个字符串的视图，而不需要传递ControllerContext, Rick Strahl在http://www.codemag.com/Article/1312081有一篇很好的文章，它创建了一个通用控制器。代码摘要如下:

// Some Static Class
public static string RenderViewToString(ControllerContext context, string viewPath, object model = null, bool partial = false)
{
    // first find the ViewEngine for this view
    ViewEngineResult viewEngineResult = null;
    if (partial)
        viewEngineResult = ViewEngines.Engines.FindPartialView(context, viewPath);
    else
        viewEngineResult = ViewEngines.Engines.FindView(context, viewPath, null);

    if (viewEngineResult == null)
        throw new FileNotFoundException("View cannot be found.");

    // get the view and attach the model to view data
    var view = viewEngineResult.View;
    context.Controller.ViewData.Model = model;

    string result = null;

    using (var sw = new StringWriter())
    {
        var ctx = new ViewContext(context, view, context.Controller.ViewData, context.Controller.TempData, sw);
        view.Render(ctx, sw);
        result = sw.ToString();
    }

    return result;
}

// In the Service Class
public class GenericController : Controller
{ }

public static T CreateController<T>(RouteData routeData = null) where T : Controller, new()
{
    // create a disconnected controller instance
    T controller = new T();

    // get context wrapper from HttpContext if available
    HttpContextBase wrapper;
    if (System.Web.HttpContext.Current != null)
        wrapper = new HttpContextWrapper(System.Web.HttpContext.Current);
    else
        throw new InvalidOperationException("Cannot create Controller Context if no active HttpContext instance is available.");

    if (routeData == null)
        routeData = new RouteData();

    // add the controller routing if not existing
    if (!routeData.Values.ContainsKey("controller") &&
        !routeData.Values.ContainsKey("Controller"))
        routeData.Values.Add("controller", controller.GetType().Name.ToLower().Replace("controller", ""));

    controller.ControllerContext = new ControllerContext(wrapper, routeData, controller);
    return controller;
}

然后在Service类中呈现View:

var stringView = RenderViewToString(CreateController<GenericController>().ControllerContext, "~/Path/To/View/Location/_viewName.cshtml", theViewModel, true);

你可以用这种方法获取字符串中的视图

protected string RenderPartialViewToString(string viewName, object model)
{
    if (string.IsNullOrEmpty(viewName))
        viewName = ControllerContext.RouteData.GetRequiredString("action");

    if (model != null)
        ViewData.Model = model;

    using (StringWriter sw = new StringWriter())
    {
        ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(ControllerContext, viewName);
        ViewContext viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
        viewResult.View.Render(viewContext, sw);

        return sw.GetStringBuilder().ToString();
    }
}

我们可以用两种方式调用这个方法

string strView = RenderPartialViewToString("~/Views/Shared/_Header.cshtml", null)

OR

var model = new Person()
string strView = RenderPartialViewToString("~/Views/Shared/_Header.cshtml", model)

对我来说最简单的方法是:

  public string GetFileAsString(string path)
  {
        var html = "";                        

        FileStream fileStream = new FileStream(path, FileMode.Open);

        using (StreamReader reader = new StreamReader(fileStream))
        {
            html += reader.ReadLine();
        }

        return html;
   }

我在电子邮件中使用这个，并确保文件只包含CSS和HTML