上一篇介紹到 CreateActionResult 方法會產生一個 ActionResult 物件利用 MethodInfo 資訊.

最後透過 InvokeActionResult 來呼叫 ExecuteResult 方法來執行 ActionResult 的 ExecuteResult 方法,基本上 MVC 找到且執行 Action 方法後面就沒再做甚麼特別的事情了(後面做資源釋放...)

protected virtual void InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
	actionResult.ExecuteResult(controllerContext);
本篇來介紹常用的ActionResult其內部運作程式碼
6種基本的ActionResult
下面這六個類別是直接繼承於ActionResult的類別(其中有標註Base class代表這是抽象類別另外有類別繼承它)
ContentResult:回傳一組字串,利用response.Write方法
EmptyResult:什麼都不動作(當Action回傳void使用)
FileResult(Base class):把檔案當作回傳
HttpStatusCodeResult:回傳HTTP狀態碼
RedirectResult & RedirectToRouteResult:使用Response.Redirect轉導到其他頁面
ViewResultBase(Base class):會找尋相對應View檔案(cshtml會編譯成一個DLL)來執行
ViewResultBase會在另一篇介紹(因為機制比較複雜)
ContentResult
在ContentResult有三個屬性
Content:響應內容.
ContentType:設置Http Header攔位ContentType
ContentEncoding:設置Encoding方式
public class ContentResult : ActionResult
    public string Content { get; set; }
    public Encoding ContentEncoding { get; set; }
    public string ContentType { get; set; }
    public override void ExecuteResult(ControllerContext context)
        if (context == null)
            throw new ArgumentNullException("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);
ContentResult操作很簡單透過response.Write把內容Print出來
RedirectResult & RedirectToRouteResult
RedirectResult這個ActionResult如其名就是導轉頁面.
Permanent:屬性判斷是否需要Permanently導轉頁面(Http-Code:RedirectPermanent=301,Redirect=302)
Url:轉導的URL透過UrlHelper.GenerateContentUrl產生URL.(在GenerateContentUrl會判斷第一個字元是否是~波浪號,如果是代表站內導轉.)
最後利用Permanent布林判斷使用RedirectPermanent還是Redirect方法.
public class RedirectResult : ActionResult
	public bool Permanent { get; private set; }
	public string Url { get; private set; }
	public override void ExecuteResult(ControllerContext context)
		if (context == null)
			throw new ArgumentNullException("context");
		if (context.IsChildAction)
			throw new InvalidOperationException(MvcResources.RedirectAction_CannotRedirectInChildAction);
		string destinationUrl = UrlHelper.GenerateContentUrl(Url, context.HttpContext);
		context.Controller.TempData.Keep();
		if (Permanent)
			context.HttpContext.Response.RedirectPermanent(destinationUrl, endResponse: false);
			context.HttpContext.Response.Redirect(destinationUrl, endResponse: false);
RedirectToRouteResult基本流程跟上面一樣只是透過UrlHelper.GenerateUrl產生要導轉URL
EmptyResult
EmptyResult這個類別很有趣,只有override ExecuteResult方法但沒有實做,上篇小結有提到這裡使用一個設計模式null object pattern.
public class EmptyResult : ActionResult
    private static readonly EmptyResult _singleton = new EmptyResult();
    internal static EmptyResult Instance
        get { return _singleton; }
    public override void ExecuteResult(ControllerContext context)
FileResult
FileResult是一個抽象類別,提供一個抽象方法給abstract void WriteFile(HttpResponseBase response)子類提供覆寫.
有兩個類別繼承於FileResult抽象類別
FilePathResult
FileContentResult
FileResult抽象類別在ExecuteResult設置傳輸檔案需要的前置作業(設置Content-Type...),最後的資料傳輸透過各個子類別去實現.
其中headerValue實做Http回應擋頭對於RFC規範.
// From RFC 2183, Sec. 2.3:
// The sender may want to suggest a filename to be used if the entity is
// detached and stored in a separate file. If the receiving MUA writes
// the entity to a file, the suggested filename should be used as a
// basis for the actual filename, where possible.
string headerValue = ContentDispositionUtil.GetHeaderValue(FileDownloadName);
public abstract class FileResult : ActionResult
        private string _fileDownloadName;
        protected FileResult(string contentType)
            if (String.IsNullOrEmpty(contentType))
                throw new ArgumentException(MvcResources.Common_NullOrEmpty, "contentType");
            ContentType = contentType;
        public string ContentType { get; private set; }
        public string FileDownloadName
            get { return _fileDownloadName ?? String.Empty; }
            set { _fileDownloadName = value; }
        public override void ExecuteResult(ControllerContext context)
            if (context == null)
                throw new ArgumentNullException("context");
            HttpResponseBase response = context.HttpContext.Response;
            response.ContentType = ContentType;
            if (!String.IsNullOrEmpty(FileDownloadName))
                string headerValue = ContentDispositionUtil.GetHeaderValue(FileDownloadName);
                context.HttpContext.Response.AddHeader("Content-Disposition", headerValue);
            WriteFile(response);
        protected abstract void WriteFile(HttpResponseBase response);
FileContentResult
FileContentResult將檔案已位元組方式轉存給Client端.
透過HttpResponseBase.OutputStream.Write方法.
public class FileContentResult : FileResult
    public FileContentResult(byte[] fileContents, string contentType)
        : base(contentType)
        if (fileContents == null)
            throw new ArgumentNullException("fileContents");
        FileContents = fileContents;
    public byte[] FileContents { get; private set; }
    protected override void WriteFile(HttpResponseBase response)
        response.OutputStream.Write(FileContents, 0, FileContents.Length);
FilePathResult
FilePathResult透過檔案名稱FileName將檔案提供給Client
藉由HttpResponseBase.TransmitFile方法.
public class FilePathResult : FileResult
    public FilePathResult(string fileName, string contentType)
        : base(contentType)
        if (String.IsNullOrEmpty(fileName))
            throw new ArgumentException(MvcResources.Common_NullOrEmpty, "fileName");
        FileName = fileName;
    public string FileName { get; private set; }
    protected override void WriteFile(HttpResponseBase response)
        response.TransmitFile(FileName);
本篇介紹了幾個實現ActionResult類別,跟其內部程式碼,這裡能了解到MVC返回結果機於ActionResult方法.(這個概念我運用在Web Api服務,建立ResponseBase共同簽章,因為在做服務串接每個服務都有自己的加解密,回傳格式攔位.我可以統一透過一個ResponseBase類別裝載資料再藉由過濾器來幫忙組成相對應的資料回傳....)
下篇會來介紹繼承ActionResult最複雜的ViewResultBase相關程式碼.