BottomBar

BottomBar是Github上的一個開源框架，因為從1.3.3開始不支持fragments了，要自己配置，弄了很久，不管是app的fragment還是V4 的程序總是總是閃退。於是就用這種方式實現了，效果還不錯。github有詳細說明，多余的就不說了。

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

添加第二個就行了，我這用到了butterknife（不知道的可以百度，出自jakewharton大神的一款View注入框架）。

從menu添加items

res/menu/bottombar_menu.xml

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 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上提供了兩種初始化方式，這裡是第二種實現下滑隱藏，因為是fragment滾動所以fragment的布局要被NestedScrollView包裹（下面貼代碼，很簡單的），同時注意viewPager.setOnPageChangeListener已經過時了。

layout/activity_main.xml

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