Android布局

android:gravity="center"

android:orientation="vertical"
android:orientation="horizontal"

android:layout_centerVertical="true"
android:layout_centerHorizontal="true"

android:layout_gravity="center_horizontal"
android:layout_gravity="center_Vertical"

android:focusable="true"
android:focusableInTouchMode="true"
listView.setItemsCanFocus(true);

ipDNS_text.requestFocus();
InputMethodManager imm = (InputMethodManager)ipDNS_text.getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
imm.toggleSoftInput(0, InputMethodManager.SHOW_FORCED);