Activity添加Fragment防止重复添加

@Override

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

if (savedInstanceState == null) {

home = new HomeFragment();
getSupportFragmentManager().beginTransaction().add(R.id.main_container, home, "home").commit();
} else {
home = (HomeFragment) getSupportFragmentManager().findFragmentByTag("home");

}

}