$scope.listenbackbutton = function() {
  document.addEventListener("plusready", onPlusReady, false);
    function onPlusReady() {
      plus.key.addEventListener("backbutton", function() {
        if ($location.path() == '/tab/index') {
          if (plus.os.name == "Android") {
            $ionicLoading.show({
              template: "再次点击返回键退出应用"
            });
              $timeout(function() {
              $ionicLoading.hide();
            plus.key.removeEventListener("backbutton", function() {});
              return;
              }, 1000);
            plus.key.addEventListener("backbutton", function() {
              plus.runtime.quit();
            });
        } else {
          outSet("此平台不支持直接退出程序，请按Home键切换应用");
          }
        } else {
          $ionicHistory.goBack();
      }
    });
  }
}