AngularJS父状态，识别状态转换

angular.module('myApp', ['ui.router'])
  .config(function($stateProvider, $urlRouterProvider) {
    $stateProvider
      .state('parent', {
        url: '/parent',
        abstract: true,
        template: '<ui-view/>'
      })
      .state('parent.child', {
        url: '/child',
        templateUrl: 'child.html',
        controller: 'ChildController'
      });

    $urlRouterProvider.otherwise('/parent/child');
  })
  .run(function($rootScope) {
    $rootScope.$on('$stateChangeStart', function(event, toState, toParams, fromState, fromParams) {
      console.log('State change started from', fromState.name, 'to', toState.name);
    });

    $rootScope.$on('$stateChangeSuccess', function(event, toState, toParams, fromState, fromParams) {
      console.log('State change succeeded from', fromState.name, 'to', toState.name);
    });

    $rootScope.$on('$stateChangeError', function(event, toState, toParams, fromState, fromParams, error) {
      console.error('State change error from', fromState.name, 'to', toState.name, ':', error);
    });
  });

$stateProvider
  .state('parent', {
    url: '/parent',
    abstract: true,
    template: '<ui-view/>',
    resolve: {
      sharedData: function(DataService) {
        return DataService.getSharedData();
      }
    }
  })
  .state('parent.child', {
    url: '/child',
    templateUrl: 'child.html',
    controller: 'ChildController',
    resolve: {
      childData: function(DataService) {
        return DataService.getChildData();
      }
    }
  });

angular.module('myApp')
  .service('SharedDataService', function() {
    this.sharedData = {};
  });

angular.module('myApp')
  .controller('ChildController', function($scope, SharedDataService) {
    $scope.sharedData = SharedDataService.sharedData;
  });