01------------------appsettings.json----------------
"JWT": {
    "SecretKey": "assdfghkldsf@123!",
    "Issuer": "2222",
    "Expires": 10,
    "Audience": "22333"
  }

02-----------------program--------------------------- 
builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme).AddJwtBearer(options =>
{
    options.TokenValidationParameters = new TokenValidationParameters()
    {
        ValidateIssuer = true,
        ValidIssuer = builder.Configuration["JWT:Issuer"],
        ValidateAudience = true,
        ValidAudience = builder.Configuration["JWT:Audience"],
        ValidateLifetime = true,
        IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(builder.Configuration["JWT:SecretKey"]))
    };
});var app = builder.Build();
//鉴权授权
app.UseAuthentication();
app.UseAuthorization();03------login---------------------------------
 [HttpGet]
        public string login()
        {
            // 1. 定义需要使?到的Claims
            var claims = new[]
            {
                new Claim("Id", "9527"),
                new Claim("Name", "Admin")
            };
            // 2. 从 appsettings.json 中读取SecretKey
            var secretKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_configuration["JWT:SecretKey"]));
            // 3. 选择加密算法
            var algorithm = SecurityAlgorithms.HmacSha256;
            // 4. ?成Credentials
            var signingCredentials = new SigningCredentials(secretKey, algorithm);
            // 5. 从 appsettings.json 中读取Expires
            var expires = Convert.ToDouble(_configuration["JWT:Expires"]);
            // 6. 根据以上，?成token
            var token = new JwtSecurityToken(
                _configuration["JWT:Issuer"],     //Issuer
                _configuration["JWT:Audience"],   //Audience
                claims,                          //Claims,
                DateTime.Now,                    //notBefore
                DateTime.Now.AddDays(expires),   //expires
                signingCredentials               //Credentials
            );
            // 7. 将token变为string
            var jwtToken = new JwtSecurityTokenHandler().WriteToken(token);
            return jwtToken;
        }