我已将自定义键盘添加到我的Fragment，现在我想在按下后退时实现关闭键盘。classCustomKeyboard{publicvoidinit(Contextcontext){//...FragmentManagerfragmentManager=((Activity)context).getFragmentManager();booleanfragmentPopped=fragmentManager.popBackStackImmediate(TAG,0);if(!fragmentPopped){FragmentTransactionfragmentTransaction=fra