我现在正在使用FileStreamResult,它可以传输视频,但无法搜索它.它总是从头开始.
我正在使用ByteRangeStreamContent,但它似乎不再可用于dnxcore50.
那怎么办？
我是否需要手动解析请求范围标头并编写自定义FileResult来设置响应Content-Range和其余标头,并将缓冲区范围写入响应主体,或者是否已经实现了某些内容并且我错过了它？
解决方法
这是一个VideoStreamResult的简单实现,我现在正在使用(多部分内容部分未经过测试)：
public class VideoStreamResult : FileStreamResult
{
// default buffer size as defined in BufferedStream type
private const int BufferSize = 0x1000;
private string MultipartBoundary = "<qwe123>";
public VideoStreamResult(Stream fileStream,string contentType)
: base(fileStream,contentType)
{
}
public VideoStreamResult(Stream fileStream,MediaTypeHeaderValue contentType)
: base(fileStream,contentType)
{
}
private bool IsMultipartRequest(RangeHeaderValue range)
{
return range != null && range.Ranges != null && range.Ranges.Count > 1;
}
private bool IsRangeRequest(RangeHeaderValue range)
{
return range != null && range.Ranges != null && range.Ranges.Count > 0;
}
protected async Task WriteVideoAsync(HttpResponse response)
{
var bufferingFeature = response.HttpContext.Features.Get<IHttpBufferingFeature>();
bufferingFeature?.DisableResponseBuffering();
var length = FileStream.Length;
var range = response.HttpContext.GetRanges(length);
if (IsMultipartRequest(range))
{
response.ContentType = $"multipart/byteranges; boundary={MultipartBoundary}";
}
else
{
response.ContentType = ContentType.ToString();
}
response.Headers.Add("Accept-Ranges","bytes");
if (IsRangeRequest(range))
{
response.StatusCode = (int)HttpStatusCode.PartialContent;
if (!IsMultipartRequest(range))
{
response.Headers.Add("Content-Range",$"bytes {range.Ranges.First().From}-{range.Ranges.First().To}/{length}");
}
foreach (var rangeValue in range.Ranges)
{
if (IsMultipartRequest(range)) // dunno if multipart works
{
await response.WriteAsync($"--{MultipartBoundary}");
await response.WriteAsync(Environment.NewLine);
await response.WriteAsync($"Content-type: {ContentType}");
await response.WriteAsync(Environment.NewLine);
await response.WriteAsync($"Content-Range: bytes {range.Ranges.First().From}-{range.Ranges.First().To}/{length}");
await response.WriteAsync(Environment.NewLine);
}
await WriteDataToResponseBody(rangeValue,response);
if (IsMultipartRequest(range))
{
await response.WriteAsync(Environment.NewLine);
}
}
if (IsMultipartRequest(range))
{
await response.WriteAsync($"--{MultipartBoundary}--");
await response.WriteAsync(Environment.NewLine);
}
}
else
{
await FileStream.CopyToAsync(response.Body);
}
}
private async Task WriteDataToResponseBody(RangeItemHeaderValue rangeValue,HttpResponse response)
{
var startIndex = rangeValue.From ?? 0;
var endIndex = rangeValue.To ?? 0;
byte[] buffer = new byte[BufferSize];
long totalToSend = endIndex - startIndex;
int count = 0;
long bytesRemaining = totalToSend + 1;
response.ContentLength = bytesRemaining;
FileStream.Seek(startIndex,SeekOrigin.Begin);
while (bytesRemaining > 0)
{
try
{
if (bytesRemaining <= buffer.Length)
count = FileStream.Read(buffer,(int)bytesRemaining);
else
count = FileStream.Read(buffer,buffer.Length);
if (count == 0)
return;
await response.Body.WriteAsync(buffer,count);
bytesRemaining -= count;
}
catch (IndexOutOfRangeException)
{
await response.Body.FlushAsync();
return;
}
finally
{
await response.Body.FlushAsync();
}
}
}
public override async Task ExecuteResultAsync(ActionContext context)
{
await WriteVideoAsync(context.HttpContext.Response);
}
}
并解析请求标头范围：
public static RangeHeaderValue GetRanges(this HttpContext context,long contentSize)
{
RangeHeaderValue rangesResult = null;
string rangeHeader = context.Request.Headers["Range"];
if (!string.IsNullOrEmpty(rangeHeader))
{
// rangeHeader contains the value of the Range HTTP Header and can have values like:
// Range: bytes=0-1 * Get bytes 0 and 1,inclusive
// Range: bytes=0-500 * Get bytes 0 to 500 (the first 501 bytes),inclusive
// Range: bytes=400-1000 * Get bytes 500 to 1000 (501 bytes in total),inclusive
// Range: bytes=-200 * Get the last 200 bytes
// Range: bytes=500- * Get all bytes from byte 500 to the end
//
// Can also have multiple ranges delimited by commas,as in:
// Range: bytes=0-500,600-1000 * Get bytes 0-500 (the first 501 bytes),inclusive plus bytes 600-1000 (401 bytes) inclusive
// Remove "Ranges" and break up the ranges
string[] ranges = rangeHeader.Replace("bytes=",string.Empty).Split(",".tocharArray());
rangesResult = new RangeHeaderValue();
for (int i = 0; i < ranges.Length; i++)
{
const int START = 0,END = 1;
long endByte,startByte;
long parsedValue;
string[] currentRange = ranges[i].Split("-".tocharArray());
if (long.TryParse(currentRange[END],out parsedValue))
endByte = parsedValue;
else
endByte = contentSize - 1;
if (long.TryParse(currentRange[START],out parsedValue))
startByte = parsedValue;
else
{
// No beginning specified,get last n bytes of file
// We already parsed end,so subtract from total and
// make end the actual size of the file
startByte = contentSize - endByte;
endByte = contentSize - 1;
}
rangesResult.Ranges.Add(new RangeItemHeaderValue(startByte,endByte));
}
}
return rangesResult;
}