前面讲了侧边栏，现在我们需要给侧边栏和主界面换成fragment。
1.建立一个基类BaseFragment,让两个子类LetfFragment、ContentFragment继承BaseFragment.
2.掏空原有布局文件，只设置布局为幁布局，将LetfFragment、ContentFragment塞进去。
public abstract class BaseFragment extends Fragment { public Activity mactivity; public void onCreate(Bundle savedInstanceState) { //创建fragment super.onCreate(savedInstanceState); mactivity = getActivity(); //获取当前fragment所依赖的Activity } //获得fragment的布局 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = initView(); return view; } //子类初始化布局 public abstract View initView(); //子类初始化数据 public abstract void initData(); }LetfFragment，ContFragment基本一样 public class LetfFragment extends BaseFragment { public View initView() { View view = View.inflate(mactivity, R.layout.fragment_left_menu, null); return view; } @Override public void initData() { } }其中一个原布局，我们将其掏空 <?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/fl_letf_menu" android:layout_width="match_parent" android:layout_height="match_parent" > </FrameLayout>