在ASP.NET Core中，使用Json Web Token (JWT)进行身份验证时，有时需要刷新令牌。为了实现这一点，你可以使用Microsoft.AspNetCore.Authentication.JwtBearer包中的RefreshToken功能。以下是如何刷新令牌的步骤：

首先，确保在Startup.cs文件中为JWT身份验证配置了RefreshToken中间件：

public void ConfigureServices(IServiceCollection services){// ...其他服务配置...services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme).AddJwtBearer(options =>{options.RequireHttpsMetadata = true;options.SaveToken = true;options.TokenValidationParameters = new TokenValidationParameters{ValidateIssuerSigningKey = true,IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(Configuration["JwtSecret"])),ValidateIssuer = false,ValidateAudience = false};}).AddJwtBearer<JwtBearerOptions>(options =>{options.SaveToken = true;}).AddRefreshToken();}public void Configure(IApplicationBuilder app, IWebHostEnvironment env){// ...其他中间件配置...app.UseAuthentication();app.UseAuthorization();// ...其他中间件配置...}

在你的控制器中，使用[Authorize]属性保护需要身份验证的路由。同时，添加一个用于处理令牌刷新的端点：

[Authorize]public class AccountController : ControllerBase{// ...其他控制器方法...[HttpPost("refresh-token")]public async Task<IActionResult> RefreshToken([FromBody] RefreshTokenRequest request){var claims = new[]{new Claim(ClaimTypes.Name, request.Username),new Claim(ClaimTypes.Email, request.Email)};var identity = new ClaimsIdentity(claims, JwtBearerDefaults.AuthenticationScheme);var principal = new ClaimsPrincipal(identity);var tokenHandler = new JwtSecurityTokenHandler();var key = Encoding.UTF8.GetBytes(Configuration["JwtSecret"]);var tokenDescriptor = new SecurityTokenDescriptor{Subject = principal,Expires = DateTime.UtcNow.AddMinutes(30),SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha256Signature)};var newToken = tokenHandler.CreateToken(tokenDescriptor);var newJwtToken = tokenHandler.WriteToken(newToken);return Ok(new JwtTokenResponse { Token = newJwtToken });}}

创建一个RefreshTokenRequest模型，用于接收客户端发送的刷新令牌请求：

public class RefreshTokenRequest{public string Username { get; set; }public string Email { get; set; }public string RefreshToken { get; set; }}

创建一个JwtTokenResponse模型，用于返回新的JWT令牌：

public class JwtTokenResponse{public string Token { get; set; }}

现在，当客户端的访问令牌过期时，它可以发送一个包含刷新令牌的请求到/account/refresh-token端点。服务器将验证刷新令牌，生成一个新的JWT令牌，并将其返回给客户端。