NetCore MVC 靜態文件生成

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.AspNetCore.Mvc.Infrastructure;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;

namespace NetCore.MVC
{
    /// <summary>
    /// 訪問靜態頁面過濾器
    /// </summary>
    [System.AttributeUsage(AttributeTargets.Method)]
    public class StaticHtmlAttribute:ActionFilterAttribute
    {
        /// <summary>
        /// 靜態路由配置
        /// </summary>
        /// <param name="url">靜態路由地址</param>
        /// <param name="idfield">數據id名稱</param>
        public StaticHtmlAttribute(string url,string idfield="id")
        {
            Url = url;
            idField = idfield;
        }
        /// <summary>
        /// 靜態文件路由
        /// </summary>
        public string Url { get; set; }
        /// <summary>
        /// 參數標識
        /// </summary>
        public string idField { get; set; }

        /// <summary>
        /// 是否清除文件標識
        /// </summary>
        private string RemoveClearKey = "remove"; 
        /// <summary>
        /// 靜態文件根目錄
        /// </summary>
        private string StaticFilesRootName
        {
            get
            {
                return ApplicationEnvironments.Site.BaseDirectory  + "html/";
            }
        }
        public override void OnActionExecuting(ActionExecutingContext context)
        {
            string id = context.RouteData.Values.ContainsKey(idField) ? context.RouteData.Values[idField].ToString() : "";
            if (string.IsNullOrEmpty(id) && context.HttpContext.Request.Query.ContainsKey(idField))
            {
                id = context.HttpContext.Request.Query[idField];
            }
            string filePath = StaticFilesRootName + string.Format(Url, id);
            //判斷文件是否存在
            if (File.Exists(filePath))
            {
                if ( context.HttpContext.Request.Query.ContainsKey(RemoveClearKey))
                {
                    RemoveClearKey = context.HttpContext.Request.Query[RemoveClearKey];
                    if (!string.IsNullOrWhiteSpace(RemoveClearKey))
                    {
                        File.Delete(filePath);
                    }
                }
                else
                {
                    //若是存在，直接讀取文件
                    using (FileStream fs = File.Open(filePath, FileMode.Open))
                    {
                        using (StreamReader sr = new StreamReader(fs, Encoding.UTF8))
                        {
                            //經過contentresult返回文件內容
                            ContentResult contentresult = new ContentResult();
                            contentresult.Content = sr.ReadToEnd();
                            contentresult.ContentType = "text/html";
                            context.Result = contentresult;
                        }
                    }
                }
            }
            base.OnActionExecuting(context);


        }
        public override void OnActionExecuted(ActionExecutedContext context)
        {

            CreateHtml(context);
            base.OnActionExecuted(context);
        }
        /// <summary>
        /// 生成html方法
        /// </summary>
        private void CreateHtml(ActionExecutedContext context)
        {
            IActionResult actionResult = context.Result;
            if (actionResult is ViewResult)
            {
                ViewResult viewResult = actionResult as ViewResult;
                //下面的代碼就是執行這個ViewResult，並把結果的html內容放到一個StringBuiler對象中
                var services = context.HttpContext.RequestServices;
                var option = services.GetRequiredService<IOptions<MvcViewOptions>>();
                var executor = services.GetRequiredService<IActionResultExecutor<ViewResult>>() as ViewResultExecutor
    ?? throw new ArgumentNullException("executor");
                var result = executor.FindView(context, viewResult);
                result.EnsureSuccessful(originalLocations: null);
                var view = result.View;
                StringBuilder builder = new StringBuilder();

                using (var writer = new StringWriter(builder))
                {
                    var viewContext = new ViewContext(
                    context,
                    view,
                    viewResult.ViewData,
                    viewResult.TempData,
                    writer,
                    option.Value.HtmlHelperOptions);

                    view.RenderAsync(viewContext).GetAwaiter().GetResult();
                    //這句必定要調用，不然內容就會是空的
                    writer.Flush();
                }
                //按照規則生成靜態文件名稱

                string id = context.RouteData.Values.ContainsKey(idField) ? context.RouteData.Values[idField].ToString() : "";
                if (string.IsNullOrEmpty(id) && context.HttpContext.Request.Query.ContainsKey(idField))
                {
                    id = context.HttpContext.Request.Query[idField];
                }
                string filePath = StaticFilesRootName + string.Format(Url, id);
                FileInfo info = new FileInfo(filePath);
                if (!info.Exists)
                {
                    if (!info.Directory.Exists)
                    {
                        info.Directory.Create();
                    }
                }

                //寫入文件
                using (FileStream fs = File.Open(filePath, FileMode.Create))
                {
                    using (StreamWriter sw = new StreamWriter(fs, Encoding.UTF8))
                    {
                        sw.Write(builder.ToString());
                    }
                }
                //輸出當前的結果
                ContentResult contentresult = new ContentResult();
                contentresult.Content = builder.ToString();
                contentresult.ContentType = "text/html";
                context.Result = contentresult;
            }
        }
        
    }
}