apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/controller/AppController.java/AppController/nav
class AppController:  @GetMapping("/{appId}/navtree")
  public MultiResponseEntity<EnvClusterInfo> nav(@PathVariable String appId) {

    MultiResponseEntity<EnvClusterInfo> response = MultiResponseEntity.ok();
    List<Env> envs = portalSettings.getActiveEnvs();
    for (Env env : envs) {
      try {
        response.addResponseEntity(RichResponseEntity.ok(appService.createEnvNavNode(env, appId)));
      } catch (Exception e) {
        response.addResponseEntity(RichResponseEntity.error(HttpStatus.INTERNAL_SERVER_ERROR,
            "load env:" + env.getName() + " cluster error." + e
                .getMessage()));
      }
    }
    return response;
  }