android 监听当前页返回键回到桌面，再次点击app回到当前页

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch(keyCode){
case KeyEvent.KEYCODE_BACK:
Intent home = new Intent(Intent.ACTION_MAIN);
home.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
home.addCategory(Intent.CATEGORY_HOME);
startActivity(home);
return true;
}
return super.onKeyDown(keyCode, event);
}

FLAG_ACTIVITY_NEW_TASK

ACTION_MAIN

String ACTION_MAIN

CATEGORY_HOME