builder.Services.AddSession(options =>
{
　　options.IdleTimeout = TimeSpan.FromMinutes(30);
　　options.Cookie.HttpOnly = true;
　　options.Cookie.IsEssential = true;

});//添加session支持
builder.Services.AddDistributedMemoryCache();//添加session支持,同时要加这句
var app = builder.Build();
app.UseSession();//使用session

public class xxController{
　　private readonly IHttpContextAccessor _httpContextAccessor;
　　private ISession _session => _httpContextAccessor.HttpContext.Session;
　　public xxController(IHttpContextAccessor httpContextAccessor){
　　　　_httpContextAccessor = httpContextAccessor;
　　}

　　public APIResult TestSession(){
　　　　if (_session.GetString("errorVcode") != null)
　　　　　　var errorVcode=_session.GetString("errorVcode").ToInt(); //取值
　　　　　_session.SetString("errorVcode",222);//设值

　　}

}