最近Google在自己推出的Material design中增加了Bottom Navigation導航控制。Android一直沒有官方的導航控制器，自己實現確實是五花八門，有了這個規定之後，就類似蘋果的底部Toolbar，以後我們的APP就會有一致的風格，先看一張效果：

這是官方在Material design中給出一張圖，確實很不錯。

1.BottomNavigationBar的下載地址

2.使用的方法

2.1在Gradle中新增

compile ‘com.ashokvarma.android:bottom-navigation-bar:0.9.5’

2.2佈局實現

 <com.ashokvarma.bottomnavigation.BottomNavigationBar
        android:layout_gravity="bottom"
        android:id="@+id/bottom_navigation_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

2.3類中Activity中新增BottomNavigationItem

BottomNavigationBar bottomNavigationBar = (BottomNavigationBar) findViewById(R.id
 
.bottom_navigation_bar);

bottomNavigationBar
                .addItem(new BottomNavigationItem(R.drawable.ic_home_white_24dp, "Home"))
                .addItem(new BottomNavigationItem(R.drawable.ic_book_white_24dp, "Books"))
                .addItem(new BottomNavigationItem(R.drawable.ic_music_note_white_24dp, "Music"
 
))
                .addItem(new BottomNavigationItem(R.drawable.ic_tv_white_24dp, "Movies & TV"))
                .addItem(new BottomNavigationItem(R.drawable.ic_videogame_asset_white_24dp, "Games"))
                .initialise();

2.4設定事件監聽器TabChangeListener

 bottomNavigationBar.setTabSelectedListener(new BottomNavigationBar.OnTabSelectedListener(){
            @Override
            public void onTabSelected(int position) {
            }
            @Override
            public void onTabUnselected(int position) {]
            }
            @Override
            public void onTabReselected(int position) {
            }
        });

3.案例的實現

佈局檔案

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/activity_navigation_view_demo"
    tools:context="com.lidong.demo.navigation_view.BottomNavigationBarDemoActivity">

    <LinearLayout
        android:id="@+id/tb"
        android:layout_width="match_parent"
         android:layout_height="match_parent"
        android:orientation="vertical" />
    <com.ashokvarma.bottomnavigation.BottomNavigationBar
        android:id="@+id/bottom_navigation_bar"
        android:layout_width="match_parent"
        android:layout_alignParentBottom="true"
        android:layout_height="wrap_content"/>
</RelativeLayout>

Activity的程式碼：

package com.lidong.demo.navigation_view;

import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;

import com.ashokvarma.bottomnavigation.BottomNavigationBar;
import com.ashokvarma.bottomnavigation.BottomNavigationItem;
import com.lidong.demo.R;

/**
 * BottomNavigationBar實現
 */
public class BottomNavigationBarDemoActivity extends AppCompatActivity implements BottomNavigationBar.OnTabSelectedListener {

    private BottomNavigationBar bottomNavigationBar;
    int lastSelectedPosition = 0;
    private String TAG = BottomNavigationBarDemoActivity.class.getSimpleName();
    private LocationFragment mLocationFragment;
    private FindFragment mFindFragment;
    private FavoritesFragment mFavoritesFragment;
    private BookFragment mBookFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_navigation_view_demo);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        bottomNavigationBar = (BottomNavigationBar) findViewById(R.id.bottom_navigation_bar);

        bottomNavigationBar
                .addItem(new BottomNavigationItem(R.mipmap.ic_location_on_white_24dp, "位置").setActiveColor(R.color.orange))
                .addItem(new BottomNavigationItem(R.mipmap.ic_find_replace_white_24dp, "發現").setActiveColor(R.color.blue))
                .addItem(new BottomNavigationItem(R.mipmap.ic_favorite_white_24dp, "愛好").setActiveColor(R.color.green))
                .addItem(new BottomNavigationItem(R.mipmap.ic_book_white_24dp, "圖書").setActiveColor(R.color.blue))
                .setFirstSelectedPosition(lastSelectedPosition )
                .initialise();

        bottomNavigationBar.setTabSelectedListener(this);
        setDefaultFragment();
    }

    /**
     * 設定預設的
     */
    private void setDefaultFragment() {
        FragmentManager fm = getFragmentManager();
        FragmentTransaction transaction = fm.beginTransaction();
        mLocationFragment = LocationFragment.newInstance("位置");
        transaction.replace(R.id.tabs, mLocationFragment);
        transaction.commit();
    }

    @Override
    public void onTabSelected(int position) {
        Log.d(TAG, "onTabSelected() called with: " + "position = [" + position + "]");
        FragmentManager fm = this.getFragmentManager();
        //開啟事務
        FragmentTransaction transaction = fm.beginTransaction();
        switch (position) {
            case 0:
                if (mLocationFragment == null) {
                    mLocationFragment = LocationFragment.newInstance("位置");
                }
                transaction.replace(R.id.tb, mLocationFragment);
                break;
            case 1:
                if (mFindFragment == null) {
                    mFindFragment = FindFragment.newInstance("發現");
                }
                transaction.replace(R.id.tb, mFindFragment);
                break;
            case 2:
                if (mFavoritesFragment == null) {
                    mFavoritesFragment = FavoritesFragment.newInstance("愛好");
                }
                transaction.replace(R.id.tb, mFavoritesFragment);
                break;
            case 3:
                if (mBookFragment == null) {
                    mBookFragment = BookFragment.newInstance("圖書");
                }
                transaction.replace(R.id.tb, mBookFragment);
                break;
            default:
                break;
        }
        // 事務提交
        transaction.commit();
    }

    @Override
    public void onTabUnselected(int position) {
        Log.d(TAG, "onTabUnselected() called with: " + "position = [" + position + "]");
    }

    @Override
    public void onTabReselected(int position) {

    }
}

fragment的程式碼

package com.lidong.demo.navigation_view;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import com.lidong.demo.R;

public class LocationFragment extends Fragment {


    public static LocationFragment newInstance(String param1) {
        LocationFragment fragment = new LocationFragment();
        Bundle args = new Bundle();
        args.putString("agrs1", param1);
        fragment.setArguments(args);
        return fragment;
    }

    public LocationFragment() {

    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_location, container, false);
        Bundle bundle = getArguments();
        String agrs1 = bundle.getString("agrs1");
        TextView tv = (TextView)view.findViewById(R.id.tv_location);
        tv.setText(agrs1);
        return view;
    }



}

程式碼實現起來很簡單，就載入佈局，新增BottomNavigationItem，設定TabChangeListener就這三步搞定底部導航控制器。

效果實現：