var app = angular.module('gzmu', ["ngRoute",'chart.js']);app.run(function ($rootScope, $http) {    $http({        method: 'GET',        url: 'datacon/user_info.php',    }).success(function (response) {            $rootScope.userinfo = response[0];        console.log($rootScope.userinfo)        $rootScope.$broadcast("userinfo", response[0]);    })});app.controller('data', function ($scope, $http, $rootScope) {    $scope.usernamea='';    $scope.$on("userinfo",        function (event, msg) {            console.log(msg);            if(msg){                $scope.usernamea = msg.user;                console.log($scope.usernamea)                alert($scope.usernamea)            }            else{                alert(msg)            }        });}）;如題，on里面的代碼為什么不會每加載一次頁面都運行一次？