dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer --version 3.1.0

public class TokenParameter
{  
 public const string Issuer = "深度码农";//颁发者  
 public const string Audience = "深度码农";//接收者  
 public const string Secret = "1234567812345678";//签名秘钥  
 public const int AccessExpiration = 30;//AccessToken过期时间（分钟）
}

[Route("api/oauth")]
[ApiController]
public class OAuthController : ControllerBase
{
 /// <summary>
 /// 获取Token
 /// </summary>
 /// <returns></returns>
 [HttpGet]
 [Route("token")]
 public ActionResult GetAccessToken(string username, string password)
 {
  //这儿在做用户的帐号密码校验。我这儿略过了。
  if (username != "admin" || password != "admin")
   return BadRequest("Invalid Request");

  var claims = new[]
  {
   new Claim(ClaimTypes.Name, username),
   new Claim(ClaimTypes.Role, ""),
  };

  var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(TokenParameter.Secret));
  var credentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);
  var jwtToken = new JwtSecurityToken(TokenParameter.Issuer, TokenParameter.Audience, claims, expires: DateTime.UtcNow.AddMinutes(TokenParameter.AccessExpiration), signingCredentials: credentials);
  var token = new JwtSecurityTokenHandler().WriteToken(jwtToken);

  return Ok(token);
 }
}

services.AddAuthentication(x =>
{
 x.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
 x.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
}).AddJwtBearer(x =>
{
 x.RequireHttpsMetadata = false;
 x.SaveToken = true;
 x.TokenValidationParameters = new TokenValidationParameters
 {     
  ValidateIssuerSigningKey = true,//是否调用对签名securityToken的SecurityKey进行验证
  IssuerSigningKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(TokenParameter.Secret)),//签名秘钥
  ValidateIssuer = true,//是否验证颁发者
  ValidIssuer = TokenParameter.Issuer, //颁发者
  ValidateAudience = true, //是否验证接收者
  ValidAudience = TokenParameter.Audience,//接收者
  ValidateLifetime = true,//是否验证失效时间
 };
});

app.UseAuthentication();//必须在app.UseAuthorization();之前

[HttpGet("{id}")]
[Authorize]
public async Task<ActionResult<Todo GetTodo(Guid id)
{
 var todo = await context.Todo.FindAsync(id);

 if (todo == null)
 {
  return NotFound();
 }

 return todo;
}