//转换fragment
public void SwitchFrag(Fragment targetFragment){
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
//如果Fragment没有被添加，则添加，否则显示
if(!targetFragment.isAdded()){
transaction.hide(currentFragment).add(R.id.dl_cebian, targetFragment).commit();
}
else{
transaction.hide(currentFragment).show(targetFragment).commit();
}
currentFragment = targetFragment;
}