//自定義HttpClientHandler實(shí)例
HttpClientHandler httpClientHandler = new HttpClientHandler
{
    AutomaticDecompression = DecompressionMethods.GZip
};
//使用傳遞自定義HttpClientHandler實(shí)例的構(gòu)造函數(shù)
using (HttpClient client = new HttpClient(httpClientHandler))
{
    var response = await client.GetAsync($"http://MyDemo/Home/GetPerson?userId={userId}");
}

[Flags]
public enum DecompressionMethods
{
    // 使用所有壓縮解壓縮算法。
    All = -1,
    // 不使用解壓
    None = 0x0,
    // 使用gzip解壓算法
    GZip = 0x1,
    // 使用deflate解壓算法
    Deflate = 0x2,
    // 使用Brotli解壓算法
    Brotli = 0x4
}

services.AddHttpClient("mydemo", c =>
{
    c.BaseAddress = new Uri("http://MyDemo/");
}).ConfigurePrimaryHttpMessageHandler(provider=> new HttpClientHandler
{
    AutomaticDecompression = DecompressionMethods.GZip
});

services.AddHttpClient("mydemo", c =>
{
    c.BaseAddress = new Uri("http://MyDemo/");
}).ConfigureHttpClient(provider => new HttpClient(new HttpClientHandler
{
    AutomaticDecompression = DecompressionMethods.GZip
}));

public DecompressionMethods AutomaticDecompression
{
    get => _underlyingHandler.AutomaticDecompression;
    set => _underlyingHandler.AutomaticDecompression = value;
}

private readonly SocketsHttpHandler _underlyingHandler;

public DecompressionMethods AutomaticDecompression
{
    get => _settings._automaticDecompression;
    set
    {
        CheckDisposedOrStarted();
        _settings._automaticDecompression = value;
    }
}

private readonly HttpConnectionSettings _settings = new HttpConnectionSettings();

if (settings._automaticDecompression != DecompressionMethods.None)
{
    handler = new DecompressionHandler(settings._automaticDecompression, handler);
}

internal override async ValueTask<HttpResponseMessage> SendAsync(HttpRequestMessage request, bool async, CancellationToken cancellationToken)
{
    //判斷是否是GZIP壓縮請(qǐng)求，如果是則添加請(qǐng)求頭Accept-Encoding頭為gzip
    if (GZipEnabled && !request.Headers.AcceptEncoding.Contains(s_gzipHeaderValue))
    {
        request.Headers.AcceptEncoding.Add(s_gzipHeaderValue);
    }
    //判斷是否是Deflate壓縮請(qǐng)求，如果是則添加請(qǐng)求頭Accept-Encoding頭為deflate
    if (DeflateEnabled && !request.Headers.AcceptEncoding.Contains(s_deflateHeaderValue))
    {
        request.Headers.AcceptEncoding.Add(s_deflateHeaderValue);
    }
    //判斷是否是Brotli壓縮請(qǐng)求，如果是則添加請(qǐng)求頭Accept-Encoding頭為brotli
    if (BrotliEnabled && !request.Headers.AcceptEncoding.Contains(s_brotliHeaderValue))
    {
        request.Headers.AcceptEncoding.Add(s_brotliHeaderValue);
    }
    //發(fā)送請(qǐng)求
    HttpResponseMessage response = await _innerHandler.SendAsync(request, async, cancellationToken).ConfigureAwait(false);

    Debug.Assert(response.Content != null);
    //獲取返回的Content-Encoding輸出頭信息
    ICollection<string> contentEncodings = response.Content.Headers.ContentEncoding;
    if (contentEncodings.Count > 0)
    {
        string? last = null;
        //獲取最后一個(gè)值
        foreach (string encoding in contentEncodings)
        {
            last = encoding;
        }
        //根據(jù)響應(yīng)頭判斷服務(wù)端采用的是否為gzip壓縮
        if (GZipEnabled && last == Gzip)
        {
            //使用gzip解壓算法解壓返回內(nèi)容，并從新賦值到response.Content
            response.Content = new GZipDecompressedContent(response.Content);
        }
        //根據(jù)響應(yīng)頭判斷服務(wù)端采用的是否為deflate壓縮
        else if (DeflateEnabled && last == Deflate)
        {
            //使用deflate解壓算法解壓返回內(nèi)容，并從新賦值到response.Content
            response.Content = new DeflateDecompressedContent(response.Content);
        }
        //根據(jù)響應(yīng)頭判斷服務(wù)端采用的是否為brotli壓縮
        else if (BrotliEnabled && last == Brotli)
        {
            //使用brotli解壓算法解壓返回內(nèi)容，并從新賦值到response.Content
            response.Content = new BrotliDecompressedContent(response.Content);
        }
    }
    return response;
}

internal bool GZipEnabled => (_decompressionMethods & DecompressionMethods.GZip) != 0;
internal bool DeflateEnabled => (_decompressionMethods & DecompressionMethods.Deflate) != 0;
internal bool BrotliEnabled => (_decompressionMethods & DecompressionMethods.Brotli) != 0;

private sealed class GZipDecompressedContent : DecompressedContent
{
        public GZipDecompressedContent(HttpContent originalContent)
            : base(originalContent)
        { }
        //使用GZipStream類對(duì)返回的流進(jìn)行解壓
        protected override Stream GetDecompressedStream(Stream originalStream) =>
            new GZipStream(originalStream, CompressionMode.Decompress);
    }

    private sealed class DeflateDecompressedContent : DecompressedContent
    {
        public DeflateDecompressedContent(HttpContent originalContent)
            : base(originalContent)
        { }
        //使用DeflateStream類對(duì)返回的流進(jìn)行解壓
        protected override Stream GetDecompressedStream(Stream originalStream) =>
            new DeflateStream(originalStream, CompressionMode.Decompress);
    }

    private sealed class BrotliDecompressedContent : DecompressedContent
    {
        public BrotliDecompressedContent(HttpContent originalContent) :
            base(originalContent)
        { }
        //使用BrotliStream類對(duì)返回的流進(jìn)行解壓
        protected override Stream GetDecompressedStream(Stream originalStream) =>
            new BrotliStream(originalStream, CompressionMode.Decompress);
    }
}