Android BottomNavigationBar底部导航如何使用

import android.graphics.Color;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.ashokvarma.bottomnavigation.BottomNavigationBar;
import com.ashokvarma.bottomnavigation.BottomNavigationItem;
import com.ashokvarma.bottomnavigation.ShapeBadgeItem;
import com.ashokvarma.bottomnavigation.TextBadgeItem;

import java.lang.reflect.Field;

public class MainActivity extends AppCompatActivity implements BottomNavigationBar.OnTabSelectedListener {

 private FragmentManager mFragmentManager;
 private BottomNavigationBar bottomNavigationBar;

 private FirstFragment firstFragment;
 private SecondFragment secondFragment;
 private ThirdFragment thirdFragment;
 private FourthFragment fourthFragment;
 //默认选择第一个fragment
 private int lastSelectedPosition = 0;
 private FragmentTransaction transaction;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

 bottomNavigationBar = this.findViewById(R.id.bottomNavigationBar);
 showNumberAndShape();
 initNavigation();
 }

 /**
 * 初始底部导航栏
 */
 private void initNavigation() {
 //导航栏Item的个数<=3 用 MODE_FIXED 模式，否则用 MODE_SHIFTING 模式
 bottomNavigationBar.setMode(BottomNavigationBar.MODE_FIXED);
 bottomNavigationBar.setTabSelectedListener(this);//监听切换点击事件
 //bottomNavigationBar.setBarBackgroundColor("#595757");//背景颜色
 //1、BACKGROUND_STYLE_DEFAULT：如果设置的Mode为MODE_FIXED，将使用BACKGROUND_STYLE_STATIC 。如果Mode为MODE_SHIFTING将使用BACKGROUND_STYLE_RIPPLE。
 //2、BACKGROUND_STYLE_STATIC：点击无水波纹效果
 //3、BACKGROUND_STYLE_RIPPLE：点击有水波纹效果
 bottomNavigationBar.setBackgroundStyle(BottomNavigationBar.BACKGROUND_STYLE_STATIC);
 //需要添加的item数
 bottomNavigationBar
  //选中时的图片的资源、文字
  .addItem(new BottomNavigationItem(R.drawable.home, "首页")
   //选中的颜色
   .setActiveColor(R.color.colorAccent)
   //选中的颜色(资源文件 下面同上)
   //.setActiveColorResource(R.color.colorAccent)
   //未选中的颜色(默认灰色 可注释)
   .setInActiveColor("#999999")
   //未选中时的图片的资源
   .setInactiveIconResource(R.drawable.ic_launcher_background))
  .addItem(new BottomNavigationItem(R.drawable.home, "订单")
   .setActiveColorResource(R.color.colorAccent)
   .setInActiveColor("#999999")
   .setInactiveIconResource(R.drawable.ic_launcher_background)).
  addItem(new BottomNavigationItem(R.drawable.ic_launcher_background, "购物车")
   .setActiveColorResource(R.color.colorAccent)
   .setInActiveColor("#999999")
   .setBadgeItem(textBadgeItem)
   .setInactiveIconResource(R.drawable.ic_launcher_background)).
  addItem(new BottomNavigationItem(R.drawable.ic_launcher_background, "我的")
   .setActiveColorResource(R.color.colorAccent)
   .setInActiveColor("#999999")
   .setBadgeItem(shapeBadgeItem)
   .setInactiveIconResource(R.drawable.ic_launcher_background))
  .setFirstSelectedPosition(lastSelectedPosition)//设置默认选中项
  //.setFab(FloatingActionButton的id)//FloatingActionButton 关联
  .initialise();//注意此句放在最后
 setIconItemMargin(bottomNavigationBar,10,25,14);
 setDefaultFragment();
 }

 /**
 * 设置默认开启的fragment
 */
 private void setDefaultFragment() {
 mFragmentManager = getSupportFragmentManager();
 FragmentTransaction transaction = mFragmentManager.beginTransaction();
 firstFragment = new FirstFragment();
 transaction.add(R.id.tb, firstFragment);
 transaction.commit();
 }

 /**
 * 切换事件
 */
 @Override
 public void onTabSelected(int position) {
 lastSelectedPosition = position;//每次点击赋值
 //开启事务
 transaction = mFragmentManager.beginTransaction();
 hideFragment(transaction);
 switch (position) {
  case 0:
  if (firstFragment == null) {
   firstFragment = new FirstFragment();
   transaction.add(R.id.tb, firstFragment);
  } else {
   transaction.show(firstFragment);
  }
  // transaction.replace(R.id.tb, firstFragment);
  break;
  case 1:
  if (secondFragment == null) {
   secondFragment = new SecondFragment();
   transaction.add(R.id.tb, secondFragment);
  } else {
   transaction.show(secondFragment);
  }
  break;
  case 2:
  if (thirdFragment == null) {
   thirdFragment = new ThirdFragment();
   transaction.add(R.id.tb, thirdFragment);
  } else {
   transaction.show(thirdFragment);
  }
  break;
  case 3:
  if (fourthFragment == null) {
   fourthFragment = new FourthFragment();
   transaction.add(R.id.tb, fourthFragment);
  } else {
   transaction.show(fourthFragment);
  }
  break;
 }
 // 事务提交
 transaction.commit();
 }

 /**
 * 隐藏当前fragment
 *
 * @param transaction
 */
 private void hideFragment(FragmentTransaction transaction) {
 if (firstFragment != null) {
  transaction.hide(firstFragment);
 }
 if (secondFragment != null) {
  transaction.hide(secondFragment);
 }
 if (thirdFragment != null) {
  transaction.hide(thirdFragment);
 }
 if (fourthFragment != null) {
  transaction.hide(fourthFragment);
 }
 }

 private TextBadgeItem textBadgeItem;
 private ShapeBadgeItem shapeBadgeItem;

 /**
 * 展示消息点
 */
 private void showNumberAndShape() {
 //消息
 textBadgeItem = new TextBadgeItem()
  .setText("99")//显示的文本
  .setTextColor("#ffffff")//文本颜色
  //.setTextColorResource(R.color.colorAccent)//文本颜色(资源文件-下面如同)
  .setBorderWidth(6)//圆环宽度
  .setBorderColor(Color.parseColor("#000000"))//圆环燕色
  //.setBorderColorResource(R.color.colorPrimary)
  .setBackgroundColor("#FF4081")//背景颜色
  .setHideOnSelect(false);//选中是否隐藏
 //.setBackgroundColorResource(R.color.colorAccent)//背景颜色
 //.setAnimationDuration(300)//隐藏与动画的过渡时间（setHideOnSelect 为true时生效）
 //.setGravity(Gravity.RIGHT | Gravity.TOP); //位置，默认右上角(可不设置)

 //形状
 shapeBadgeItem = new ShapeBadgeItem()
  //也可设置为常量 （0-6之间）
  .setShape(ShapeBadgeItem.SHAPE_HEART) //形状
  .setShapeColor(Color.RED) //颜色
  //.setShapeColorResource(R.color.colorPrimaryDark) //（同上）
  .setEdgeMarginInDp(this, 0) //距离Item的边距，dp值
  //.setEdgeMarginInPixels(20) //距离Item的边距，px
  .setSizeInDp(this, 15, 15) //宽高值，dp
  //.setSizeInPixels(30, 30) //宽高值，px
  .setAnimationDuration(300) //隐藏和展示的动画速度，单位毫秒,和setHideOnSelect一起使用
  //.setGravity(Gravity.LEFT) //位置，默认右上角
  .setHideOnSelect(false); //true：当选中状态时消失，非选中状态显示,moren false
 }

 @Override
 public void onTabUnselected(int position) {
 }

 @Override
 public void onTabReselected(int position) {
 }

 /**
 * 修改间距及图片文字大小
 * @param bottomNavigationBar
 * @param space 文字与图片的间距
 * @param imgLen 单位：dp，图片大小
 * @param textSize 单位：dp，文字大小
 */
 private void setIconItemMargin(BottomNavigationBar bottomNavigationBar, int space, int imgLen, int textSize){
 Class barClass = bottomNavigationBar.getClass();
 Field[] fields = barClass.getDeclaredFields();
 for(int i = 0; i < fields.length; i++){
  Field field = fields[i];
  field.setAccessible(true);
  if(field.getName().equals("mTabContainer")){
  try{
   //反射得到 mTabContainer
   LinearLayout mTabContainer = (LinearLayout) field.get(bottomNavigationBar);
   for(int j = 0; j < mTabContainer.getChildCount(); j++){
   //获取到容器内的各个Tab
   View view = mTabContainer.getChildAt(j);
   //获取到Tab内的各个显示控件
   FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, dip2px(56));
   FrameLayout container = (FrameLayout) view.findViewById(R.id.fixed_bottom_navigation_container);
   container.setLayoutParams(params);
   container.setPadding(dip2px(12), dip2px(0), dip2px(12), dip2px(0));

   //获取到Tab内的文字控件
   TextView labelView = (TextView) view.findViewById(com.ashokvarma.bottomnavigation.R.id.fixed_bottom_navigation_title);
   //计算文字的高度DP值并设置，setTextSize为设置文字正方形的对角线长度，所以：文字高度（总内容高度减去间距和图片高度）*根号2即为对角线长度，此处用DP值，设置该值即可。
   labelView.setTextSize(TypedValue.COMPLEX_UNIT_DIP, textSize);
   labelView.setIncludeFontPadding(false);
   labelView.setPadding(0,0,0,dip2px(20-textSize - space/2));

   //获取到Tab内的图像控件
   ImageView iconView = (ImageView) view.findViewById(com.ashokvarma.bottomnavigation.R.id.fixed_bottom_navigation_icon);
   //设置图片参数，其中，MethodUtils.dip2px()：换算dp值
   params = new FrameLayout.LayoutParams(dip2px(imgLen), dip2px(imgLen));
   params.setMargins(0,0,0,space/2);
   params.gravity = Gravity.BOTTOM | Gravity.CENTER_HORIZONTAL;
   iconView.setLayoutParams(params);
   }
  } catch (IllegalAccessException e){
   e.printStackTrace();
  }
  }
 }
 }

 private int dip2px(float dpValue) {
 final float scale = getApplication().getResources().getDisplayMetrics().density;
 return (int) (dpValue * scale + 0.5f);
 }
}

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class FirstFragment extends Fragment {

 @Override
 public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

 View view = inflater.inflate(R.layout.activity_first_fragment, container, false);

 return view;
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:gravity="center">

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="第一个Fragment"
 android:textSize="30sp" />
</LinearLayout>

 switch (position) {
  case 0:
  firstFragment = new FirstFragment();
  transaction.replace(R.id.tb, firstFragment);
  break;
  case 1:
  secondFragment = new SecondFragment();
  transaction.replace(R.id.tb, secondFragment);
  break;
  case 2:
  thirdFragment = new ThirdFragment();
  transaction.replace(R.id.tb, thirdFragment);
  break;
  case 3:
  fourthFragment = new FourthFragment();
  transaction.replace(R.id.tb, fourthFragment);
  break;
 }