BottomBar

　　BottomBar是Github上的一个开源框架，因为从1.3.3开始不支持fragments了，要自己配置，弄了很久，不管是app的fragment还是V4 的程序总是总是闪退。于是就用这种方式实现了，效果还不错。github有详细说明，多余的就不说了。

　　这个roughike是这个项目的所有者（大神致敬）。

　　我用的是android studio开发，fragment全部导的V4的包（以为最开始就支持的是v4的，后面也支持了app.fragment）.

首先是dependencies

compile ‘com.jakewharton:butterknife:7.0.0‘
compile ‘com.roughike:bottom-bar:1.3.3‘

添加第二个就行了，我这用到了butterknife（不知道的可以百度，出自jakewharton大神的一款View注入框架）。

从menu添加items

res/menu/bottombar_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/bb_menu_recents"
        android:icon="@drawable/ic_recents"
        android:title="Recents" />
    <item
        android:id="@+id/bb_menu_favorites"
        android:icon="@drawable/ic_favorites"
        android:title="Favorites" />
    <item
        android:id="@+id/bb_menu_nearby"
        android:icon="@drawable/ic_nearby"
        android:title="Nearby" />
    <item
        android:id="@+id/bb_menu_friends"
        android:icon="@drawable/ic_friends"
        android:title="Friends" />
    <item
        android:id="@+id/bb_menu_food"
        android:icon="@drawable/ic_restaurants"
        android:title="Food" />
</menu>

在activity中初始化BottomBar和ViewPager

public class MainActivity extends FragmentActivity {
    @Bind(R.id.viewPager)
    ViewPager viewPager;
    @Bind(R.id.myCoordinator)
    CoordinatorLayout myCoordinator;

    private BottomBar mBottomBar;
    private List<Fragment> fragmentList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
        initViewPager();
        createBottomBar(savedInstanceState);
    }

    private void createBottomBar(Bundle savedInstanceState) {
        mBottomBar = BottomBar.attachShy(myCoordinator,viewPager, savedInstanceState);
        mBottomBar.setItemsFromMenu(R.menu.bottombar_menu, new OnMenuTabClickListener() {
            @Override
            public void onMenuTabSelected(@IdRes int menuItemId) {
                switch (menuItemId) {
                    case R.id.bb_menu_recents:
                        viewPager.setCurrentItem(0);
                        break;
                    case R.id.bb_menu_favorites:
                        viewPager.setCurrentItem(1);
                        break;
                    case R.id.bb_menu_nearby:

                        break;
                    case R.id.bb_menu_friends:

                        break;
                    case R.id.bb_menu_food:

                        break;
                }
            }

            @Override
            public void onMenuTabReSelected(@IdRes int menuItemId) {

            }
        });

        // Setting colors for different tabs when there‘s more than three of them.
        // You can set colors for tabs in three different ways as shown below.
        mBottomBar.mapColorForTab(0, ContextCompat.getColor(this, R.color.colorAccent));
        mBottomBar.mapColorForTab(1, 0xFF5D4037);
        mBottomBar.mapColorForTab(2, "#7B1FA2");
        mBottomBar.mapColorForTab(3, "#FF5252");
        mBottomBar.mapColorForTab(4, "#FF9800");
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        // Necessary to restore the BottomBar‘s state, otherwise we would
        // lose the current tab on orientation change.
        mBottomBar.onSaveInstanceState(outState);
    }

    private void initViewPager() {
        fragmentList = new ArrayList<>();
        fragmentList.add(new FragmentOne());
        fragmentList.add(new FragmentTwo());
        viewPager.setAdapter(new FragmentStatePagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int position) {
                return fragmentList.get(position);
            }

            @Override
            public int getCount() {
                return fragmentList.size();
            }
        });
        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                mBottomBar.selectTabAtPosition(position, true);
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

    }
}

　　BottomBar的github上提供了两种初始化方式，这里是第二种实现下滑隐藏，因为是fragment滚动所以fragment的布局要被NestedScrollView包裹（下面贴代码，很简单的），同时注意viewPager.setOnPageChangeListener已经过时了。

layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/myCoordinator"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.example.bottombar.bottombar.MainActivity">

        <android.support.v4.view.ViewPager
            android:id="@+id/viewPager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>

    </android.support.design.widget.CoordinatorLayout>

FragmentOne.java

public class FragmentOne extends Fragment {
    View v;
    Context context;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        v = inflater.inflate(R.layout.fragment_one, container,false);
        context = getActivity();
        return v;
    }
}

layout/fragment_one.xml

<?xml version="1.0" encoding="utf-8"?>

<android.support.v4.widget.NestedScrollView
    android:id="@+id/myScrollView"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="20dp">
    <TextView
        android:layout_centerInParent="true"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/baiduInfo"/>

    </RelativeLayout>
</android.support.v4.widget.NestedScrollView>

　　over收工，图标资源文件放在代码里了。代码已经上传：

点我下载哦