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

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();

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

package com.android.xiaobai; 
 
import android.os.Bundle; 
import android.support.annotation.Nullable; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentTransaction; 
import android.support.v7.app.AppCompatActivity; 
import android.util.Log; 
 
import com.ashokvarma.bottomnavigation.BottomNavigationBar; 
import com.ashokvarma.bottomnavigation.BottomNavigationItem; 
 
import java.util.ArrayList; 
 
import fragment.ContactsFragment; 
import fragment.DongtaiFragment; 
import fragment.MsgFragment; 
 
/** 
 * Created by xiaobai on 2018/1/31/031. 
 */ 
 
public class MessageActivity extends AppCompatActivity implements BottomNavigationBar.OnTabSelectedListener { 
 private ArrayList fragments; 
 private BottomNavigationBar bottomNavigationBar; 
 private MsgFragment msgFragment; 
 private ContactsFragment contactsFragment; 
 private DongtaiFragment dongtaiFragment; 
 private FragmentManager fragmentManager; 
 private FragmentTransaction transaction; 
 int lastSelectedPosition = 0; 
 
 @Override 
 protected void onCreate(@Nullable Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
 setContentView(R.layout.activty_message); 
 
 bottomNavigationBar = findViewById(R.id.bottom_navigation_bar); 
 init(); 
 } 
 
 private void init() { 
 //要先设计模式后再添加图标！ 
 //设置按钮模式 MODE_FIXED表示固定 MODE_SHIFTING表示转移 
 bottomNavigationBar.setMode(BottomNavigationBar.MODE_FIXED); 
 //设置背景风格 
 // BACKGROUND_STYLE_STATIC表示静态的 
 //BACKGROUND_STYLE_RIPPLE表示涟漪的，也就是可以变化的 ，跟随setActiveColor里面的颜色变化 
 bottomNavigationBar.setBackgroundStyle(BottomNavigationBar.BACKGROUND_STYLE_RIPPLE); 
 //添加并设置图标、图标的颜色和文字 
 bottomNavigationBar 
  .addItem(new BottomNavigationItem(R.drawable.im_botton_message, "消息")).setActiveColor(R.color.blue) 
  .addItem(new BottomNavigationItem(R.drawable.im_botton_contacts, "联系人")).setActiveColor(R.color.red) 
  .addItem(new BottomNavigationItem(R.drawable.im_botton_dongtai, "动态")).setActiveColor(R.color.orign) 
  .setFirstSelectedPosition(lastSelectedPosition ) 
  .initialise(); 
 
 bottomNavigationBar.setTabSelectedListener(this); 
 setDefaultFragment(); 
 } 
 
 //设置初始界面 
 private void setDefaultFragment() { 
 fragmentManager = getSupportFragmentManager(); 
 transaction = fragmentManager.beginTransaction(); 
 transaction.replace(R.id.layFrame, MsgFragment.newInstance("消息")); 
 transaction.commit(); 
 } 
 
 @Override 
 public void onTabSelected(int position) { 
 fragmentManager = getSupportFragmentManager(); 
 transaction = fragmentManager.beginTransaction(); 
 switch (position) { 
  case 0: 
  if (msgFragment == null) { 
   msgFragment = MsgFragment.newInstance("消息"); 
  } 
  transaction.replace(R.id.layFrame, msgFragment); 
  break; 
  case 1: 
  if (contactsFragment == null) { 
   contactsFragment = ContactsFragment.newInstance("联系人"); 
  } 
  transaction.replace(R.id.layFrame, contactsFragment); 
  break; 
  case 2: 
  if (dongtaiFragment == null) { 
   dongtaiFragment = DongtaiFragment.newInstance("动态"); 
  } 
  transaction.replace(R.id.layFrame, dongtaiFragment); 
  break; 
  default: 
  break; 
 } 
 // 事务提交 
 transaction.commit(); 
 } 
 
 @Override 
 public void onTabUnselected(int position) { 
 Log.d("dongtaiFragment", "onTabUnselected() called with: " + "position = [" + position + "]"); 
 } 
 
 @Override 
 public void onTabReselected(int position) { 
 
 } 
} 

package fragment; 
 
import android.os.Bundle; 
import android.support.annotation.Nullable; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 
 
import com.android.xiaobai.R; 
 
/** 
 * Created by xiaobai on 2018/1/31/031. 
 */ 
 
public class MsgFragment extends BaseFragment { 
 /** 
 * 标志位，标志已经初始化完成 
 */ 
 private boolean isPrepared; 
 /** 
 * 是否已被加载过一次，第二次就不再去请求数据了 
 */ 
 private boolean mHasLoadedOnce; 
 TextView textView; 
 @Nullable 
 @Override 
 public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { 
 if (mView == null) { 
  // 需要inflate一个布局文件 填充Fragment 
  mView = inflater.inflate(R.layout.fragment_msg, container, false); 
  initView(); 
  isPrepared = true; 
// 实现懒加载 
  lazyLoad(); 
 } 
 //缓存的mView需要判断是否已经被加过parent， 如果有parent需要从parent删除，要不然会发生这个mView已经有parent的错误。 
 ViewGroup parent = (ViewGroup) mView.getParent(); 
 if (parent != null) { 
  parent.removeView(mView); 
 } 
 
 return mView; 
 } 
 /** 
 * 初始化控件 
 */ 
 private void initView() { 
 
 } 
 
 @Override 
 public void lazyLoad() { 
 if (!isPrepared || !isVisible || mHasLoadedOnce) { 
  return; 
 } 
 //填充各控件的数据 
 mHasLoadedOnce = true; 
 } 
 public static MsgFragment newInstance(String param1) { 
 MsgFragment fragment = new MsgFragment(); 
 Bundle args = new Bundle(); 
 args.putString("agrs1", param1); 
 fragment.setArguments(args); 
 return fragment; 
 } 
} 

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

package fragment; 
 
import android.support.v4.app.Fragment; 
import android.view.View; 
 
 
/** 
 * Created by xiaobai on 2018/1/31/031. 
 */ 
 
public abstract class BaseFragment extends Fragment { 
 /** 
 * Fragment当前状态是否可见 
 */ 
 public boolean isVisible; 
 
 /** 
 * inflate布局文件 返回的view 
 */ 
 public View mView; 
 
 /** 
 * 简化 findViewById 
 * 
 * @param viewId 
 * @param  
 * @return 
 */ 
 protected  T find(int viewId) { 
 return (T) mView.findViewById(viewId); 
 } 
 
 /** 
 * setUserVisibleHint是在onCreateView之前调用的 
 * 设置Fragment可见状态 
 */ 
 @Override 
 public void setUserVisibleHint(boolean isVisibleToUser) { 
 super.setUserVisibleHint(isVisibleToUser); 
 /** 
  * 判断是否可见 
  */ 
 if (getUserVisibleHint()) { 
  isVisible = true; 
  onVisible(); 
 } else { 
  isVisible = false; 
  onInvisible(); 
 } 
 } 
 
 /** 
 * 可见 
 */ 
 private void onVisible() { 
 lazyLoad(); 
 } 
 
 /** 
 * 不可见 
 */ 
 private void onInvisible() { 
 } 
 
 /** 
 * 延迟加载 
 * 子类必须重写此方法 
 */ 
 public abstract void lazyLoad(); 
}