如何在angularjs(1x)控制器中全局使用变量？

app.controller('MyController', function($scope, $rootScope) {
  $rootScope.globalVariable = 'Hello World';
});

app.service('GlobalService', function() {
  this.globalVariable = 'Hello World';
});

app.controller('MyController', function($scope, GlobalService) {
  $scope.globalVariable = GlobalService.globalVariable;
});

app.controller('MyController', function($scope, $rootScope) {
  $rootScope.$broadcast('globalVariableUpdated', 'Hello World');
});

app.controller('AnotherController', function($scope) {
  $scope.$on('globalVariableUpdated', function(event, data) {
    $scope.globalVariable = data;
  });
});