从浏览器获取请求下载文件流

Question

我正在开发一项下载大文件的服务。有一个 Web 前端，它发送一个 get 请求，该请求以流的形式接收文件。我已经研究过 Streamsaver.js，但我不想要中间人。目前使用方式是这样的

async function downloadFileFromStream(fileName, streamRef) {
    // Get the stream from the .NET stream reference
    const response = await streamRef.stream();
    const readableStream = response.getReader();
    const fileStream = streamSaver.createWriteStream(fileName);

    if (window.WritableStream && readableStream.pipeTo) {
        await readableStream.pipeTo(fileStream);
        return;
    }

    const writer = fileStream.getWriter();
    

    const pump = () => readableStream.read()
        .then(({ done, value }) => {
            if (done) {
                writer.close();
                return;
            }
            return writer.write(value).then(pump);
        });

    await pump();
}

// To register the function in the global window object so it can be called from C#
window.downloadFileFromStream = downloadFileFromStream;

我想知道是否有类似于我在 C# 中完成的方法

伪代码

Readstream r;
Writestream w;

r.copyToAsync(w);

Answer 1

javascript:

window.downloadFileFromStream = async function (fileName, streamRef) {
    const response = await streamRef.stream();
    const reader = response.getReader();

    const writableStream = new WritableStream({
        async write(chunk, controller) {
            await writer.write(chunk);
        },
        close() {
            writer.close();
        }
    });

    const writer = writableStream.getWriter();

    const pump = () => reader.read().then(({ done, value }) => {
        if (done) {
            writer.close();
            return;
        }
        return writer.write(value).then(pump);
    });

    await pump();
}

包含这个js文件。

@page "/download"
@inject IJSRuntime JS

<button @onclick="DownloadFile">Download File</button>

@code {
    private async Task DownloadFile()
    {
        var streamRef = new DotNetStreamReference(await GetFileStream());
        await JS.InvokeVoidAsync("downloadFileFromStream", "example.txt", streamRef);
    }

    private async Task<Stream> GetFileStream()
    {
        var stream = new MemoryStream();
        using (var writer = new StreamWriter(stream, leaveOpen: true))
        {
            await writer.WriteAsync("Example file content");
        }
        stream.Position = 0;
        return stream;
    }
}