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c# - 如何处理传输编码 : chunked when downloading a file with . NET Core HttpClient.PostAsync

转载 作者:行者123 更新时间:2023-12-05 03:03:59 25 4
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情况

我正在使用 HttpClient(System.Net.Http,Version=4.2.1.0)将包含多部分表单数据的 HTTP 请求发布到 Web API。表单数据包括一个字符串参数(benchmark)和一个包含在stream中的文件(addressFile)。 API 调用返回一个 CSV 文件,我想将该文件保存到磁盘。

响应包含 header Transfer-Encoding: chunkedresponseBytes 中包含的数据包括 block header 。我期望 HttpClient 库去除这些 header ,这些 header 是实际内容的元数据。相反,它只是在 Content 中包含标题行。

问题

处理这些 block 头的正确方法是什么?

我当然可以自己编写一个方法来处理 header ,但我很难相信 HttpClient 库还没有在某处内置此功能。

代码

using (var client = new HttpClient())
{
var content = new MultipartFormDataContent();
content.Add(new StringContent("Public_AR_Current"), "benchmark");
content.Add(new ByteArrayContent(stream.ToArray()), "addressFile", "addressFile.csv");

var response = await client.PostAsync("https://geocoding.geo.census.gov/geocoder/locations/addressbatch", content);

var responseBytes = await response.Content.ReadAsByteArrayAsync();
saveResponse(responseBytes);

var geocodedItems = ParseGeocodeResponse(responseBytes);
var parsedItems = geocodedItems.Select(gi => gi.ToEpaHandlerUsCensusGeocode());
return parsedItems;
}

结果

注意第一行和后续行的 block 头(0fe800600fe8)。

0fe8
0fe8
"AK0000036228","500 HOLLYWOOD DR, ANCHORAGE, AK, 99501","Match","Exact","500 HOLLYWOOD DR, ANCHORAGE, AK, 99501","-149.87424,61.23034","190797469","R"
"AK0000363994","3155 E 18TH CIR, ANCHORAGE, AK, 99508","Match","Non_Exact","3155 E 18TH CIR, ANCHORAGE, AK, 99508","-149.82193,61.20462","190799569","L"
...
0060
28712","N 65 DEG 35 15 W 167 DEG 55 18, WALES, AK, 99734","No_Match"
"AK0000112227","KODIAK ARPR
...
0fe8
T AREA, KODIAK, AK, 99615","No_Match"
"AK0000033902","2130 E DIMOND BLVD, ANCHORAGE, AK, 99515","Match","Non_Exact","2130 W DIMOND BLVD, ANCHORAGE, AK, 99515","-149.91881,61.1375","190795925","L"
"AK0000562769","3100 TONGASS AVE, KETCHIKAN, AK, 99901-5746","No_Match"

预期结果

我希望 header 被 HttpClient 库删除。

"AK0000036228","500 HOLLYWOOD DR, ANCHORAGE, AK, 99501","Match","Exact","500 HOLLYWOOD DR, ANCHORAGE, AK, 99501","-149.87424,61.23034","190797469","R"
"AK0000363994","3155 E 18TH CIR, ANCHORAGE, AK, 99508","Match","Non_Exact","3155 E 18TH CIR, ANCHORAGE, AK, 99508","-149.82193,61.20462","190799569","L"
"AK0000228718","1050 ASPEN ST, FAIRBANKS, AK, 99709-5501","Match","Exact","1050 ASPEN ST, FAIRBANKS, AK, 99709","-147.7731,64.8535","605310042","L"
"AK0000536714","SMITH COVE IN SMITH LAGOON T74S R86E CRM S17 & 20, KASAAN, AK, 99901","No_Match"
"AK0001413822","USS-12403, N BANK WOOD RIVER, ALEKNAGIK, AK, 99555","No_Match"
"AK0000489567","BREAKWATER BTWN WESTERN AVE & TAIT ST, METLAKATLA, AK, 99926","No_Match"

最佳答案

我最终编写了这个扩展方法,它对我的​​用例来说表现足够好。

    public static Task<Stream> ReadAsStreamAsync(this HttpContent content, bool isChunked)
{
if (!isChunked)
{
return content.ReadAsStreamAsync();
}
else
{
var task = content.ReadAsStreamAsync()
.ContinueWith<Stream>((streamTask) =>
{
var outputStream = new MemoryStream();
var buffer = new char[1024 * 1024];
var stream = streamTask.Result;

// No using() so that we don't dispose stream.
var tr = new StreamReader(stream);
var tw = new StreamWriter(outputStream);

while (!tr.EndOfStream)
{
var chunkSizeStr = tr.ReadLine().Trim();
var chunkSize = int.Parse(chunkSizeStr, System.Globalization.NumberStyles.HexNumber);

tr.ReadBlock(buffer, 0, chunkSize);
tw.Write(buffer, 0, chunkSize);
tr.ReadLine();
}

return outputStream;
});

return task;
}


}

关于c# - 如何处理传输编码 : chunked when downloading a file with . NET Core HttpClient.PostAsync,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53356925/

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