dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer

dotnet add package System.IdentityModel.Tokens.Jwt

    public class JwtOptions
    {
        /// <summary>
        /// 簽發(fā)者
        /// </summary>
        public string Issuer { get; set; }

        /// <summary>
        /// 接收者
        /// </summary>
        public string Audience { get; set; }

        /// <summary>
        /// 密鑰
        /// </summary>
        public string Key { get; set; }

        /// <summary>
        /// 過期時間
        /// </summary>
        public int ExpireSeconds { get; set; }
    }

  "JWT": {
    "Issuer": "簽發(fā)方",
    "Audience": "接受方",
    "Key": "A86DA130-1B95-4748-B3B2-1B6AA9F2F743",//加密密鑰
    "ExpireSeconds": 600 //密鑰過期時間
  }

    public static class JWTExtensions
    {
        public static AuthenticationBuilder AddJWTAuthentication(this IServiceCollection services, JwtOptions jwtOptions)
        {
            return services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
                .AddJwtBearer(x =>
                {
                    x.TokenValidationParameters = new()
                    {
                        ValidateIssuer = true,//是否驗(yàn)證發(fā)行商
                        ValidateAudience = true,//是否驗(yàn)證受眾者
                        ValidateLifetime = true,//是否驗(yàn)證失效時間
                        ValidateIssuerSigningKey = true,//是否驗(yàn)證簽名鍵
                        ValidIssuer = jwtOptions.Issuer,
                        ValidAudience = jwtOptions.Audience,
                        IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(jwtOptions.Key))
                    };
                });
        }
    }

    public static class SwaggerGenOptionsExtensions
    {
        /// <summary>
        /// 為swagger增加Authentication報文頭
        /// </summary>
        /// <param name="option"></param>
        public static void AddAuthenticationHeader(this SwaggerGenOptions option)
        {
            option.AddSecurityDefinition("Authorization",
                new OpenApiSecurityScheme
                {
                    Description = "Authorization header. \r\nExample:Bearer 12345ABCDE",
                    Name = "Authorization",
                    In = ParameterLocation.Header,
                    Type = SecuritySchemeType.ApiKey,
                    Scheme = "Authorization"
                }
                ); ;

            option.AddSecurityRequirement(new OpenApiSecurityRequirement()
            {
                {
                    new OpenApiSecurityScheme
                    {
                        Reference=new OpenApiReference
                        {
                            Type=ReferenceType.SecurityScheme,
                            Id="Authorization"
                        },
                        Scheme="oauth2",
                        Name="Authorization",
                        In=ParameterLocation.Header,
                    },
                    new List<string>()
                }
            });
        }
    }

    public interface IJwtService
    {
        string BuildToken(IEnumerable<Claim> claims, JwtOptions options);
    }

    public class JwtService : IJwtService
    {
        public string BuildToken(IEnumerable<Claim> claims, JwtOptions options)
        {
            //過期時間
            TimeSpan timeSpan = TimeSpan.FromSeconds(options.ExpireSeconds);//token過期時間
            var securityKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(options.Key));//加密的token密鑰
            var credentials = new SigningCredentials(securityKey, SecurityAlgorithms.HmacSha256Signature);//簽名證書，其值為securityKey和HmacSha256Signature算法
            var tokenDescriptor = new JwtSecurityToken(options.Issuer, options.Audience, claims, expires: DateTime.Now.Add(timeSpan), signingCredentials: credentials);//表示jwt token的描述信息，其值包括Issuer簽發(fā)方，Audience接收方，Claims載荷，過期時間和簽名證書
            return new JwtSecurityTokenHandler().WriteToken(tokenDescriptor);//使用該方法轉(zhuǎn)換為字符串形式的jwt token返回
        }
    }

builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddScoped<IJwtService, JwtService>();
JwtOptions jwtOpt = builder.Configuration.GetSection("JWT").Get<JwtOptions>();
builder.Services.AddJWTAuthentication(jwtOpt);
builder.Services.Configure<SwaggerGenOptions>(c =>
{
    c.AddAuthenticationHeader();
});

var app = builder.Build();
app.UseSwagger();
app.UseSwaggerUI();
app.UseHttpsRedirection();
app.UseAuthentication();//注意，一定得先啟動這個
app.UseAuthorization();
//以下回答來自GPT
//app.UseAuthentication()是啟用身份驗(yàn)證中間件，它會驗(yàn)證請求中的身份信息，并將身份信息存儲在HttpContext.User屬性中。而app.UseAuthorization()是啟用授權(quán)中間件，它會檢查HttpContext.User中的身份信息是否有訪問當(dāng)前請求所需的權(quán)限。
//一定要先啟用身份驗(yàn)證中間件再啟用授權(quán)中間件，因?yàn)槭跈?quán)中間件需要使用身份驗(yàn)證中間件存儲的身份信息來進(jìn)行權(quán)限驗(yàn)證。如果沒有啟用身份驗(yàn)證中間件，授權(quán)中間件將無法獲取到身份信息，從而無法進(jìn)行權(quán)限驗(yàn)證。
app.MapControllers();
app.Run();

    [ApiController]
    [Route("[controller]/[action]")]
    [Authorize]
    public class WeatherForecastController : ControllerBase
    {
        private static readonly string[] Summaries = new[]
        {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };

        private readonly ILogger<WeatherForecastController> _logger;
        //jwt服務(wù)

        private readonly IJwtService _jwtService;

        private readonly IConfiguration _configuration;

        public WeatherForecastController(ILogger<WeatherForecastController> logger, IJwtService jwtService, IConfiguration configuration)
        {
            _logger = logger;
            _jwtService = jwtService;
            _configuration = configuration;
        }

        [HttpGet]
        public IEnumerable<WeatherForecast> Get()
        {
            return Enumerable.Range(1, 5).Select(index => new WeatherForecast
            {
                Date = DateTime.Now.AddDays(index),
                TemperatureC = Random.Shared.Next(-20, 55),
                Summary = Summaries[Random.Shared.Next(Summaries.Length)]
            })
            .ToArray();
        }

        //AllowAnonymous允許匿名訪問
        [AllowAnonymous, HttpGet]
        public string GetToken()
        {
            var jwtopntion = _configuration.GetSection("JWT").Get<JwtOptions>();
            List<Claim> claims = new List<Claim>();
            claims.Add(new Claim(ClaimTypes.Name, "用戶1"));
            claims.Add(new Claim(ClaimTypes.Role, "超級管理員"));
            return _jwtService.BuildToken(claims, jwtopntion);
        }
    }