asp.net-mvc - 从操作写入输出流

Question

由于一些奇怪的原因，我想将 HTML 从 Controller 操作直接写入响应流。(我理解MVC分离，但这是一个特例。)

我可以直接写入 HttpResponse 流吗？在这种情况下， Controller 操作应返回哪个 IView 对象？我可以返回“null”吗？

Answer 1

我使用从 FileResult 派生的类来使用正常的 MVC 模式来实现此目的:

/// <summary>
/// MVC action result that generates the file content using a delegate that writes the content directly to the output stream.
/// </summary>
public class FileGeneratingResult : FileResult
{
    /// <summary>
    /// The delegate that will generate the file content.
    /// </summary>
    private readonly Action<System.IO.Stream> content;

    private readonly bool bufferOutput;

    /// <summary>
    /// Initializes a new instance of the <see cref="FileGeneratingResult" /> class.
    /// </summary>
    /// <param name="fileName">Name of the file.</param>
    /// <param name="contentType">Type of the content.</param>
    /// <param name="content">Delegate with Stream parameter. This is the stream to which content should be written.</param>
    /// <param name="bufferOutput">use output buffering. Set to false for large files to prevent OutOfMemoryException.</param>
    public FileGeneratingResult(string fileName, string contentType, Action<System.IO.Stream> content,bool bufferOutput=true)
        : base(contentType)
    {
        if (content == null)
            throw new ArgumentNullException("content");

        this.content = content;
        this.bufferOutput = bufferOutput;
        FileDownloadName = fileName;
    }

    /// <summary>
    /// Writes the file to the response.
    /// </summary>
    /// <param name="response">The response object.</param>
    protected override void WriteFile(System.Web.HttpResponseBase response)
    {
        response.Buffer = bufferOutput;
        content(response.OutputStream);
    }
}

Controller 方法现在如下所示:

public ActionResult Export(int id)
{
    return new FileGeneratingResult(id + ".csv", "text/csv",
        stream => this.GenerateExportFile(id, stream));
}

public void GenerateExportFile(int id, Stream stream)
{
    stream.Write(/**/);
}

请注意，如果缓冲关闭，

stream.Write(/**/);

变得极其缓慢。解决方案是使用 BufferedStream。在一种情况下，这样做可以将性能提高大约 100 倍。参见

Unbuffered Output Very Slow