写入输出流的操作

问题描述

由于一些奇怪的原因，我想直接写HTML从控制器操作的响应流。
（我的理解MVC分离，但这是一个特例。）

For some strange reasons, I want to write HTML directly to the Response stream from a controller action.(I understand MVC separation, but this is a special case.)

我可以直接写入到的Htt presponse流？在这种情况下，它的iView对象应控制器动作应该返回？我可以返回'空'？

Can I write directly into the HttpResponse stream? In that case, which IView object should the controller action should return? Can I return 'null'?

推荐答案

我使用 FileResult 派生的类来实现这个正常使用MVC模式：

I used a class derived from FileResult to achieve this using normal MVC pattern:

/// <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);
    }
}

控制器方法现在会是这样的：

The controller method would now be like this:

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(/**/);
}

注意，如果缓冲被关闭，

Note that if buffering is turned off,

stream.Write(/**/);

变得极为缓慢。的解决方案是使用一个BufferedStream。约这样做更好的性能在一个案件100倍。见

becomes extremely slow. The solution is to use a BufferedStream. Doing so improved performance by approximately 100x in one case. See

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