/// <summary>
/// 读取为二进制数组并转换为指定的编码
/// </summary>
/// <param name="httpContent"></param>
/// <param name="dstEncoding">目标编码</param>
/// <exception cref="ArgumentException"></exception>
/// <returns></returns>
public static async Task <byte[]> ReadAsByteArrayAsync(this HttpContent httpContent, Encoding dstEncoding)
{
var encoding = httpContent.GetEncoding();
var byteArray = await httpContent.ReadAsByteArrayAsync().ConfigureAwait(false);
return(encoding.Equals(dstEncoding)
? byteArray
: Encoding.Convert(encoding, dstEncoding, byteArray));
}