C# Can'；无法使用HttpClient获取API资源

我使用的是Identity Server4，我使用

ResourceOwnerPassword

grant类型配置了一个web API项目

Web API方法：

[HttpGet]
[Authorize(Roles = "Badmin")]
[Route("GetUsers")]
public IActionResult GetUsers()
{
    List<ApplicationUser> users = _context.ApplicationUsers
        .AsNoTracking().ToListAsync().Result;

    return Json(users);
}

第二种方式：

if (response != null)
{
    HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create("https://localhost:44366/identity/GetUsers");
    httpWebRequest.ContentType = "application/json";
    httpWebRequest.Headers.Add("Authorization", string.Format("Bearer {0}", response.AccessToken));
    httpWebRequest.Method = "GET";

    HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();

    string result = string.Empty;

    using (Stream responseStream = httpWebResponse.GetResponseStream())
    {
        if (responseStream != null)
        {
            StreamReader streamReader = new StreamReader(responseStream);
            result = streamReader.ReadToEnd();
            streamReader.Close();
        }
    }

    Console.WriteLine("HttpWebRequest ResourceOwnerPassword Result: " + Environment.NewLine + JsonConvert.DeserializeObject(result));
}

查看控制台结果：

所以我的问题是为什么当我使用

HttpCliet

时，我会得到未经授权的（代码401），

---

而第二种方法成功地获取了用户数据。

在发出请求之前，应将令牌添加到客户端，并且您需要确保它是授权标头

这就是为什么它在第二个例子中有效，而不是在第一个例子中

如果使用

ToListAsync

[HttpGet]
[Authorize(Roles = "Badmin")]
[Route("GetUsers")]
public async Task<IActionResult> GetUsers() {
    var users = await _context.ApplicationUsers.AsNoTracking().ToListAsync();

    return Json(users);
}

[HttpGet]
[授权（Roles=“Badmin”）]
[路由（“GetUsers”）]
公共异步任务GetUsers（）{
var users=wait_context.ApplicationUsers.AsNoTracking（）.ToListAsync（）；
返回Json（用户）；
}

client.DefaultRequestHeaders.Authorization = 
    new AuthenticationHeaderValue("Bearer", response.AccessToken);

//OR

//client.DefaultRequestHeaders
//  .Add("Authorization", string.Format("Bearer {0}", response.AccessToken));

var resourceOwnerPasswordResponse = await client.GetAsync("https://localhost:44366/identity/GetUsers");

[HttpGet]
[Authorize(Roles = "Badmin")]
[Route("GetUsers")]
public async Task<IActionResult> GetUsers() {
    var users = await _context.ApplicationUsers.AsNoTracking().ToListAsync();

    return Json(users);
}