FileResult is an abstract base class for all the others.
FileContentResult- you use it when you have a byte array you would like to return as a fileFilePathResult- when you have a file on disk and would like to return it's content (you give a path)FileStreamResult- you have a stream open, you want to return it's content as a file
However, you'll rarely have to use these classes - you can just use one of Controller.Fileoverloads and let asp.net mvc do the magic for you.
protected internal FilePathResult File(string fileName, string contentType);protected internal virtual FilePathResult File(string fileName, string contentType, string fileDownloadName);protected internal FileContentResult File(byte[] fileContents, string contentType);protected internal virtual FileContentResult File(byte[] fileContents, string contentType, string fileDownloadName);protected internal FileStreamResult File(Stream fileStream, string contentType);protected internal virtual FileStreamResult File(Stream fileStream, string contentType, string fileDownloadName);
FilePathResult
public ActionResult FilePathDownload1(){ var path = Server.MapPath("~/Files/BarcodeConverter.exe"); return File(path, "application/x-zip-compressed");}public ActionResult FilePathDownload2(){ var path = Server.MapPath("~/Files/BarcodeConverter.exe"); return File("g:\\BarcodeConverter.exe", "application/x-zip-compressed", "BarcodeConverter.exe"); } public ActionResult FilePathDownload3(){ var path = Server.MapPath("~/Files/BarcodeConverter.exe"); var name = Path.GetFileName(path); return File(path, "application/x-zip-compressed", name); }//FilePathDownload3 下载后的文件名还是默认为了 Action 的名字。原因是 fileDownloadName 将作为 URL 的一部分，只能包含 ASCII 码。所以，我们需要对name进行encode Url.Encodepublic ActionResult FilePathDownload4() { var path = Server.MapPath("~/Files/BarcodeConverter.exe"); var name = Path.GetFileName(path); return File(path, "application/x-zip-compressed",Url.Encode(name)); }
FileContentResult
FileContentResult 可以直接将 byte[] 以文件形式发送至浏览器（而不用创建临时文件）
public FileResult Download(){ byte[] fileBytes = System.IO.File.ReadAllBytes(@"c:\folder\myfile.txt"); string fileName = "myfile.txt"; return File(fileBytes, System.Net.Mime.MediaTypeNames.Application.Octet, fileName);} FileStreamResult
想给 FileStreamResult 找一个恰当的例子是不太容易的，毕竟 Http Response 中已经包含了一个OutputStream属性，
如果要动态生成文件的话，可以直接向这个输出流中写入数据，效率还高。
当然，我们不会在 Controller 中直接向 Response 的 OutputStream 写入数据，这样做是不符合MVC的，我们应该把这个操作封装成一个 ActionResult。
不过仔细想想，用途还是有的，比如服务器上有个压缩（或加密）文件，需要解压（或解密）后发送给用户，或者转发（或盗链）
（1）解压（或解密）
public ActionResult FileStreamDownload1(){ var path = Server.MapPath("~/Files/myfile.zip"); var fileStream = new FileStream(path, FileMode.Open); var zipInputStream = new ZipInputStream(fileStream); var entry = zipInputStream.GetNextEntry(); return File(zipInputStream, "application/pdf", Url.Encode(entry.Name));//假定压缩文件中只有一个文件，且是 pdf 格式的。} （2）转发（或盗链）
将其它网站上的文件作为本站文件下载（其实就是盗链）：
public ActionResult FileStreamDownload1(){ var stream = new WebClient().OpenRead("http://files.cnblogs.com/level/test.rar"); return File(stream, "application/x-zip-compressed", "test.rar"); }
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