apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/controller/SignInController.java/SignInController/login
class SignInController:  @GetMapping("/signin")
  public String login(@RequestParam(value = "error", required = false) String error,
                      @RequestParam(value = "logout", required = false) String logout) {
    return "login.html";
  }