Question

我正在将字符串写入export class UserInfoComponent extends Component { constructor(props){ super(props); this.state = {user: this.props.user} } componentWillReceiveProps(nextProps){ this.setState({user: nextProps.user}) } render() { if(this.state.user) return ( <h1>{this.state.user.firstName}</h1> ); return ( <h1>loading</h1> ) } }我需要将流返回到Controller Action，以便将其作为文件发送下载。

通常，我将Stream包装在using语句中，但是，在这种情况下，我需要返回它。我退货后还能处理吗？或者我需要以某种方式自行处理它？

MemoryStream

Controller Action返回文件：

//inside CsvOutputFormatter
public Stream GetStream(object genericObject)
{
    var stream = new MemoryStream();
    var writer = new StreamWriter(stream, Encoding.UTF8);
    writer.Write(_stringWriter.ToString());
    writer.Flush();
    stream.Position = 0;
    return stream;
}

Answer 1

根据此处的源代码 aspnetwebstack/src/System.Web.Mvc/FileStreamResult.cs

是

protected override void WriteFile(HttpResponseBase response) { // grab chunks of data and write to the output stream Stream outputStream = response.OutputStream; using (FileStream) { byte[] buffer = new byte[BufferSize]; while (true) { int bytesRead = FileStream.Read(buffer, 0, BufferSize); if (bytesRead == 0) { // no more data break; } outputStream.Write(buffer, 0, bytesRead); } } }

调用
时传递的流是FileStream
return File(stream, "application/octet-stream", "forums.csv");

<强>更新

您的问题最初被标记为Asp.Net MVC，但代码看起来像是最新的核心框架。

在那里找到它虽然写得不一样，但它在技术上做同样的事情。

aspnet/Mvc/blob/dev/src/Microsoft.AspNetCore.Mvc.Core/Infrastructure/FileStreamResultExecutor.cs

private static async Task WriteFileAsync(ActionContext context, FileStreamResult result) { var response = context.HttpContext.Response; var outputStream = response.Body; using (result.FileStream) { await result.FileStream.CopyToAsync(outputStream, BufferSize); } }

从动作返回文件时，流是否会被处置？

1 个答案:

是