如何以编程方式检查 JWT 令牌过期并自动注销用户？

Question

我有这个函数可以创建令牌并且它有到期时间：

private string CreateJWT(User user)
    {
        var secretKey = configuration.GetSection("AppSettings:Key").Value;
        var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(secretKey));

        var claims = new Claim[] {
            new Claim(ClaimTypes.Name, user.Username),
            new Claim(ClaimTypes.NameIdentifier, user.Id.ToString())
        };

        var signingCredentials = new SigningCredentials(
                                key, SecurityAlgorithms.HmacSha256Signature);

        var tokenDescriptor = new SecurityTokenDescriptor{
            Subject = new ClaimsIdentity(claims),
            Expires = DateTime.UtcNow.AddMinutes(1),
            SigningCredentials = signingCredentials
        };

        var tokenHandler = new JwtSecurityTokenHandler();
        var token = tokenHandler.CreateToken(tokenDescriptor);
        return tokenHandler.WriteToken(token);
    }

在登录控制器中，我正在分配令牌：

loginRes.Token = CreateJWT(user);

现在在我的应用程序中如何检查令牌是否过期？如果过期了，如何在没有用户交互的情况下注销用户？

我尝试过以下方法：

ngOnInit() {

this.token = localStorage.getItem("token");

if (this.token.expired !== true)
{
  localStorage.removeItem("token"); 
  this.router.navigate(["user/login"]);
}

token.expired 未定义。

Answer 1

我通过向事件添加计时器找到了解决方案：

this.token = localStorage.getItem("token");

timer(0, 600000).subscribe(() => { 

  const parseJwt = (this.token);        
  const decode = JSON.parse(atob(this.token.split('.')[1]));
  console.log(decode);
  if (decode.exp * 1000 < new Date().getTime()) 
  {
    localStorage.removeItem('token');
    localStorage.removeItem('chosenfolder');
    localStorage.removeItem('userName');
    localStorage.removeItem('isAdmin');
    localStorage.removeItem('userId');
    this.router.navigate(["user/login"]);
    this.alertify.error("Session Expired!")
  }