HarmonyOS 如何监听物理返回键

示例参考如下：

onWillDismiss: (dismissDialogAction: DismissDialogAction) => {
  console.log('dialog onWillDismiss reason: ' + dismissDialogAction.reason);
  // 1、PRESS_BACK    点击三键back、左滑/右滑、键盘ESC。 
  // 2、TOUCH_OUTSIDE    点击遮障层时 
  // 3、CLOSE_BUTTON    点击关闭按钮 
  if (dismissDialogAction.reason === DismissReason.PRESS_BACK) {
    // 处理业务逻辑后通过dismiss主动关闭对话框 
    // dismissDialogAction.dismiss(); 
  }
  if (dismissDialogAction.reason === DismissReason.TOUCH_OUTSIDE) {
    // dismissDialogAction.dismiss(); 
  }
}

详情请参考：https://developer.huawei.com/consumer/cn/doc/harmonyos-faqs-V5/faqs-arkui-282-V5