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一、引言

本文介绍了在 .NET 8 Web 应用程序中通过 AppUser 类实现 JWT 令牌身份验证的过程。JWT 身份验证是保护 API 的标准方法之一，它允许无状态身份验证，因为签名令牌是在客户端和服务器之间传递的。

二、什么是 JSON Web 令牌？

JSON Web 令牌（JWT）是一种开放标准（RFC 7519），它定义了一种紧凑且自包含的方式，用于将信息作为 JSON 对象在各方之间安全地传输。此信息是经过数字签名的，因此可以验证和信任。可以使用密钥（使用 HMAC 算法）或使用 RSA 或 ECDSA 的公钥/私钥对对 JWT 进行签名。

三、什么是 JSON Web 令牌结构？

在其紧凑形式中，JSON Web 令牌由三个部分组成，由点（.）分隔，它们是：

• 页眉
• 有效载荷
• 签名

因此，JWT 通常如下所示：xxxxx.yyyyy.zzzzz

四、设置 JWT 令牌身份验证

4.1 创建新的 .NET 8 Web API 项目

dotnet new webapi -n JwtAuthApp

4.2 安装所需的 NuGet 软件包

dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer
dotnet add package Microsoft.IdentityModel.Tokens

4.3 创建 JWT 配置模型

using System.Globalization;
namespace JwtAuthApp.JWT
{public class JwtConfiguration{public string Issuer { get; } = string.Empty;public string Secret { get; } = string.Empty;public string Audience { get; } = string.Empty;public int ExpireDays { get; }public JwtConfiguration(IConfiguration configuration){var section = configuration.GetSection("JWT");Issuer = section[nameof(Issuer)];Secret = section[nameof(Secret)];Audience = section[nameof(Audience)];ExpireDays = Convert.ToInt32(section[nameof(ExpireDays)], CultureInfo.InvariantCulture);}}
}

4.4 将 JWT 配置添加到您的 appsettings.json 中

{"Jwt": {"Issuer": "JwtAuthApp","Audience": "https://localhost:7031/","Secret": "70FC177F-3667-453D-9DA1-AF223DF6C014","ExpireDays": 30}
}

4.5 为 Configuration 配置 DIProgram.cs

builder.Services.AddTransient<JwtConfiguration>();

4.6 配置 JWT 身份验证扩展

using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.DataProtection;
using Microsoft.IdentityModel.Tokens;
using System;
using System.Text;namespace JwtAuthApp.JWT
{public static class JwtAuthBuilderExtensions{public static AuthenticationBuilder AddJwtAuthentication(this IServiceCollection services, IConfiguration configuration){var jwtConfiguration = new JwtConfiguration(configuration);services.AddAuthorization();return services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme).AddJwtBearer(options =>{options.SaveToken = true;options.TokenValidationParameters = new TokenValidationParameters{ValidateIssuer = true,ValidateAudience = true,ValidateLifetime = true,ValidateIssuerSigningKey = true,ValidIssuer = jwtConfiguration.Issuer,ValidAudience = jwtConfiguration.Audience,IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(jwtConfiguration.Secret)),ClockSkew = TimeSpan.Zero};options.Events = new JwtBearerEvents{OnMessageReceived = context =>{var token = context.Request.Headers["Authorization"].ToString()?.Replace("Bearer ", "");if (!string.IsNullOrEmpty(token)){context.Token = token;}return Task.CompletedTask;}};});}}
}

4.7 在 Program.cs 配置

var builder = WebApplication.CreateBuilder(args);// Add services to the container.
builder.Services.AddControllers();
builder.Services.AddJwtAuthentication(builder.Configuration);var app = builder.Build();// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{app.UseSwagger();app.UseSwaggerUI();
}app.UseHttpsRedirection();
app.UseAuthentication();
app.UseAuthorization();app.MapControllers();app.Run();

4.8 创建 Token 生成服务

using Microsoft.IdentityModel.Tokens;
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Text;namespace JwtAuthApp.JWT
{public class TokenService{private readonly JwtConfiguration _config;public TokenService(JwtConfiguration config){_config = config;}public string GenerateToken(string userId, string email){var claims = new[]{new Claim(JwtRegisteredClaimNames.Sub, userId),new Claim(JwtRegisteredClaimNames.Email, email)};var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_config.Secret));var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);var token = new JwtSecurityToken(issuer: _config.Issuer,audience: _config.Audience,claims: claims,expires: DateTime.Now.AddDays(_config.ExpireDays),signingCredentials: creds);return new JwtSecurityTokenHandler().WriteToken(token);}}
}

4.9 注册 Token Service

builder.Services.AddTransient<TokenService>();

4.10 添加登录端点或控制器

app.MapPost("/login", [FromBody] LoginRequest request, TokenService tokenService)
{if (request.Username == "admin" && request.Password == "admin"){var userId = "123456"; // 从数据库获取用户 IDvar email = "[e-mail]"; // 从数据库获取用户邮箱var token = tokenService.GenerateToken(userId, email);return Results.Ok(new { token });}return Results.Unauthorized();
})
.WithName("Login")
.RequireAuthorization();

4.11 新增 SwaggerConfiguration（方便测试）

using Microsoft.OpenApi.Models;
using Swashbuckle.AspNetCore.SwaggerGen;namespace JwtAuthApp.JWT
{public static class SwaggerConfiguration{public static void Configure(SwaggerGenOptions options){options.SwaggerDoc("v1", new OpenApiInfo{Title = "JWT Auth API",Version = "v1",Description = "A sample API for JWT Authentication"});options.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme{Description = "JWT Authorization header using the Bearer scheme.",Name = "Authorization",In = ParameterLocation.Header,Type = SecuritySchemeType.Http,Scheme = "Bearer",BearerFormat = "JWT"});options.AddSecurityRequirement(new OpenApiSecurityRequirement{{new OpenApiSecurityScheme{Reference = new OpenApiReference{Type = ReferenceType.SecurityScheme,Id = "Bearer"}},Array.Empty<string>()}});}}
}

4.12 添加 AppUser

 
public class AppUser : ClaimsPrincipal{ public AppUser(IHttpContextAccessor contextAccessor) : base(contextAccessor.HttpContext.User) { }public string UserID => FindFirst(CustomerConst.UserID)?.Value ?? "";public string OpenId => FindFirst(CustomerConst.OpenId)?.Value ?? ""; }builder.Services.AddHttpContextAccessor();
builder.Services.AddTransient<AppUser>();

4.13 为所有 Controller 或端点添加 Authorize 属性

app.MapGet("/weatherforecast", [Authorize] () =>
{// ...
})
.WithName("GetWeatherForecast")
.WithOpenApi();app.MapGet("/user", [Authorize] (AppUser user) =>
{return Results.Ok(new { user.Email });
})
.WithName("GetUserEmail")
.WithOpenApi();

五、测试

• 所有端点
• 获取天气预报在登录前收到错误 401 （未授权）
• 登录返回的 jwt 令牌
• 在 Swagger Auth 中使用 jwt 令牌
• 获取天气预报返回结果
• 获取用户电子邮件 返回用户电子邮件