ASP.NET MVC 下载文件

如何从 MVC 控制器（.NET Framework）下载文件。
使用 从 ASP.NET MVC 中的控制器下载任何文件类型FileStreamResult。注意：如果使用ASP.NET Core，请参阅此页面，如果想要将文件上传到服务器，请参阅此页面。

// download a zip file as an attachment
public FileStreamResult DownloadZipFile()
{
    string path = Server.MapPath("/files/somefile.zip");
    if (System.IO.File.Exists(path))
    {
        Response.AppendHeader("content-disposition", "attachment;filename=somefile.zip");
        System.IO.FileStream stream = new System.IO.FileStream(path, System.IO.FileMode.Open); // don't use using keyword!
        return new FileStreamResult(stream, "application/x-zip-compressed"); // the constructor will fire Dispose() when done
    }
    else
        return null;
}

// download a jpeg as an attachment
public FileStreamResult DownloadJpegFile()
{
    string path = Server.MapPath("/files/someimage.jpg");
    if (System.IO.File.Exists(path))
    {
        Response.AppendHeader("content-disposition", "attachment;filename=someimage.jpg");
        System.IO.FileStream stream = new System.IO.FileStream(path, System.IO.FileMode.Open); // don't use using keyword!
        return new FileStreamResult(stream, "image/jpeg"); // the constructor will fire Dispose() when done
    }
    else
        return null;
}

// download a text file as an attachment
public FileStreamResult DownloadTextFile()
{
    string path = Server.MapPath("/files/somefile.txt");
    if (System.IO.File.Exists(path))
    {
        Response.AppendHeader("content-disposition", "attachment;filename=somefile.txt");
        System.IO.FileStream stream = new System.IO.FileStream(path, System.IO.FileMode.Open); // don't use using keyword!
        return new FileStreamResult(stream, "text/plain"); // the constructor will fire Dispose() when done
    }
    else
        return null;
}

FileContentResult从使用字节数组的 ASP.NET MVC 控制器下载任何数据类型。 

public FileContentResult DownloadTextFile()
{
    byte[] bytes = System.Text.Encoding.ASCII.GetBytes("How now brown cow.");
    Response.AppendHeader("content-disposition", "attachment;filename=sometext.txt");
    return new FileContentResult(bytes, "text/plain");
} 

或者使用FileStream来填充字节数组。 

public FileContentResult DownloadTextFile()
{
    System.IO.FileStream stream = new System.IO.FileStream("somefile.txt", System.IO.FileMode.Open);
    byte[] bytes = new byte[stream.Length];
    stream.Read(bytes, 0, bytes.Length);
    Response.AppendHeader("content-disposition", "attachment;filename=somefile.txt");
    return new FileContentResult(bytes, "text/plain");
} 

或者简单来说： 

public FileContentResult DownloadTextFile()
{
    byte[] bytes = System.IO.File.ReadAllBytes("somefile.txt");
    Response.AppendHeader("content-disposition", "attachment;filename=somefile.txt");
    return new FileContentResult(bytes, "text/plain");
} 

下载自MemoryStream： 

public FileContentResult DownloadFromMemoryStream()
{
    using(System.IO.MemoryStream ms = new System.IO.MemoryStream())
    {
        ms.WriteByte((byte)'a');
        ms.WriteByte((byte)'b');
        ms.WriteByte((byte)'c');
        byte[] bytes = ms.ToArray();
        Response.AppendHeader("content-disposition", "attachment;filename=somefile.txt");
        return new FileContentResult(bytes, "text/plain");
    }
} 

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