1. 设计底部导航栏页面

1.1. 创建必须的文件夹

在res下创建color和menu文件夹

color文件夹：用于存放导航栏的个性化颜色

menu文件夹：用于存放导航栏的子项

1.2. 设计主页面

首先设计子项: menu下新建nav_items.xml文件

设计个性化颜色，color文件夹下新建nav_item_color.xml

然后再主页面中引入子项，在activity_main.xml写

2. 设计逻辑函数

点击每个子项都可以跳转到对应的页面上去

首先创建三个fragment： MainFragment, SearchFragment, AccountFragment

然后再主页面中写逻辑函数

package com.example.myapplication;import android.support.annotation.NonNull;import android.support.design.widget.BottomNavigationView;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentTransaction;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.MenuItem;import android.widget.FrameLayout;public class MainActivity extends AppCompatActivity {    private BottomNavigationView mMainNav;    private FrameLayout mMainFrame;    private HomeFragment homeFragment;    private SearchFragment searchFragment;    private AccountFragment accountFragment;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mMainFrame = (FrameLayout)findViewById(R.id.main_frame);        mMainNav = (BottomNavigationView)findViewById(R.id.main_nav);        homeFragment = new HomeFragment();        searchFragment = new SearchFragment();        accountFragment = new AccountFragment();        // 设置默认的fragment        setFragment(homeFragment);        mMainNav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {            @Override            public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {                switch (menuItem.getItemId()){                    case R.id.nav_homes:                        setFragment(homeFragment);                        return true;                    case R.id.nav_searchs:                        setFragment(searchFragment);                        return true;                    case R.id.nav_accounts:                        setFragment(accountFragment);                        return true;                    default:                        return false;                }            }        });    }//    根据传入的framgment对象，对现在设置新的fragment    private void setFragment(Fragment fragment) {        FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();        fragmentTransaction.replace(R.id.main_frame, fragment);        fragmentTransaction.commit();    }}