使用 IdentityServer4 生成无密码的访问令牌

我已经使用 ROPC 流创建了受 IdentityServer4 保护的 ASP.NET Core WebApi（使用以下示例：https://github.com/robisim74/AngularSPAWebAPI https://github.com/robisim74/AngularSPAWebAPI).

如何在没有密码的情况下从服务器手动生成access_token？

[HttpPost("loginas/{id}")]
[Authorize(Roles = "admin")]
public async Task<IActionResult> LoginAs(int id, [FromServices] ITokenService TS, 
    [FromServices] IUserClaimsPrincipalFactory<ApplicationUser> principalFactory,
    [FromServices] IdentityServerOptions options)
{
    var Request = new TokenCreationRequest();                        
    var User = await userManager.FindByIdAsync(id.ToString());
    var IdentityPricipal = await principalFactory.CreateAsync(User);
    var IdServerPrincipal = IdentityServerPrincipal.Create(User.Id.ToString(), User.UserName, IdentityPricipal.Claims.ToArray());

    Request.Subject = IdServerPrincipal;
    Request.IncludeAllIdentityClaims = true;
    Request.ValidatedRequest = new ValidatedRequest();
    Request.ValidatedRequest.Subject = Request.Subject;
    Request.ValidatedRequest.SetClient(Config.GetClients().First());
    Request.Resources = new Resources(Config.GetIdentityResources(), Config.GetApiResources());
    Request.ValidatedRequest.Options = options;
    Request.ValidatedRequest.ClientClaims = IdServerPrincipal.Claims.ToArray();

    var Token = await TS.CreateAccessTokenAsync(Request);
    Token.Issuer = "http://" + HttpContext.Request.Host.Value;

    var TokenValue = await TS.CreateSecurityTokenAsync(Token);
    return Ok(TokenValue);
}

对于新发布的 IdentityServer 2.0.0，代码需要一些修改：

[HttpPost("loginas/{id}")]
[Authorize(Roles = "admin")]
public async Task<IActionResult> LoginAs(int id, [FromServices] ITokenService TS, 
    [FromServices] IUserClaimsPrincipalFactory<ApplicationUser> principalFactory, 
    [FromServices] IdentityServerOptions options)
{
    var Request = new TokenCreationRequest();
    var User = await userManager.FindByIdAsync(id.ToString());
    var IdentityPricipal = await principalFactory.CreateAsync(User);
    var IdentityUser = new IdentityServerUser(User.Id.ToString());
    IdentityUser.AdditionalClaims = IdentityPricipal.Claims.ToArray();
    IdentityUser.DisplayName = User.UserName;
    IdentityUser.AuthenticationTime = System.DateTime.UtcNow;
    IdentityUser.IdentityProvider = IdentityServerConstants.LocalIdentityProvider;
    Request.Subject = IdentityUser.CreatePrincipal();
    Request.IncludeAllIdentityClaims = true;
    Request.ValidatedRequest = new ValidatedRequest();
    Request.ValidatedRequest.Subject = Request.Subject;
    Request.ValidatedRequest.SetClient(Config.GetClients().First());
    Request.Resources = new Resources(Config.GetIdentityResources(), Config.GetApiResources());
    Request.ValidatedRequest.Options = options;
    Request.ValidatedRequest.ClientClaims = IdentityUser.AdditionalClaims;
    var Token = await TS.CreateAccessTokenAsync(Request);
    Token.Issuer = HttpContext.Request.Scheme + "://" + HttpContext.Request.Host.Value;
    var TokenValue = await TS.CreateSecurityTokenAsync(Token);
    return Ok(TokenValue);
}