要求：

1.上方栏有标题 

2.中间显示内容，内容随下方栏的选择而切换

3.下方栏分成四个小板块可点击切换

实现步骤：

xml文件：

top.xml
界面上方栏标题。

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.demo06">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="experiment1"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">


        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

bottom.xml
界面下方四个小bottom可相互切换，点击之后界面的图标变为绿色，没有使用的界面的图标为灰色。bottom中用LinearLayout中嵌套LinearLayout。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/bottom"
    android:layout_width="match_parent"
    android:layout_height="80dp"
    android:background="@drawable/bottom_bar"
    android:baselineAligned="false"
    android:orientation="horizontal">

    <LinearLayout
        android:id="@+id/weixin"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical">

        <ImageButton
            android:id="@+id/imageButton_weixin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:background="#000000"
            android:clickable="false"
            app:srcCompat="@drawable/tab_weixin_pressed"
            android:contentDescription="TODO" />

        <TextView
            android:id="@+id/textView_1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center_horizontal"
            android:text="微信"
            android:background="#000000"
            android:textColor="#ffffff"
            android:clickable="false"
            android:textSize="15sp"
            android:visibility="visible"
            tools:visibility="visible" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/frd"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical">

        <ImageButton
            android:id="@+id/imageButton_frd"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#000000"
            android:clickable="false"
            android:contentDescription="@string/todo"
            app:srcCompat="@drawable/tab_find_frd_normal" />

        <TextView
            android:id="@+id/textView_2"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center_horizontal"
            android:clickable="false"
            android:background="#000000"
            android:text="朋友"
            android:textColor="#ffffff"
            android:textSize="15sp" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/contacts"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical">

        <ImageButton
            android:id="@+id/imageButton_contacts"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#000000"
            android:clickable="false"
            android:contentDescription="TODO"
            app:srcCompat="@drawable/tab_address_normal" />

        <TextView
            android:id="@+id/textView_3"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center_horizontal"
            android:clickable="false"
            android:text="通讯录"
            android:background="#000000"
            android:textColor="#ffffff"
            android:textSize="15sp" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/settings"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical">

        <ImageButton
            android:id="@+id/imageButton_settings"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#000000"
            android:clickable="false"
            android:contentDescription="TODO"
            app:srcCompat="@drawable/tab_settings_normal" />

        <TextView
            android:id="@+id/textView_4"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center_horizontal"
            android:clickable="false"
            android:text="设置"
            android:background="#000000"
            android:textColor="#ffffff"
            android:textSize="15sp" />
    </LinearLayout>

</LinearLayout>

Fragment_Blank
界面中间显示内容，用四个BlankFragment分别对应四个主界面。四个Fragment_Blank代码基本一样只需要修改文本内容即可，这里展示第一个微信界面的Fragment_Blank1

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/frag1"
    android:layout_width="match_parent"

    android:layout_height="match_parent"
    android:background="#ffffff"
    tools:context=".Blank1Fragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="这里是微信"
        android:textSize="100px" />

</FrameLayout>

activity_main.xml
主界面需要用到插件FrameLayout和include。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/top"
    android:layout_width="match_parent"
    android:layout_height="65dp"
    android:layout_gravity="center_horizontal"
    android:background="#dddddd"
    android:orientation="vertical">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"

        android:background="#dddddd"
        android:text="WeChat"
        android:textSize="30sp" />
</LinearLayout>

二、Java代码实现

MainActivity.java

package com.example.experiment1;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentTransaction;
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.ImageButton;
import android.widget.LinearLayout;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Blank1Fragment f1;
    private Blank2Fragment f2;
    private Blank3Fragment f3;
    private Blank4Fragment f4;

    private LinearLayout foot1;
    private LinearLayout foot2;
    private LinearLayout foot3;
    private LinearLayout foot4;

    private ImageButton mImgWeixin;
    private ImageButton mImgFrd;
    private ImageButton mImgAddress;
    private ImageButton mImgSettings;

    @SuppressLint("WrongViewCast")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.mylayout);

        foot1 = (LinearLayout) findViewById(R.id.weixin);
        foot2 = (LinearLayout) findViewById(R.id.frd);
        foot3 = (LinearLayout) findViewById(R.id.contacts);
        foot4 = (LinearLayout) findViewById(R.id.settings);
        mImgWeixin = (ImageButton)findViewById(R.id.imageButton_weixin);
        mImgFrd = (ImageButton)findViewById(R.id.imageButton_frd);
        mImgAddress = (ImageButton)findViewById(R.id.imageButton_contacts);
        mImgSettings = (ImageButton)findViewById(R.id.imageButton_settings);

        foot1.setOnClickListener(this);
        foot2.setOnClickListener(this);
        foot3.setOnClickListener(this);
        foot4.setOnClickListener(this);

        initFragment1();
    }

    private void initFragment1(){
        //开启事务，fragment的控制是由事务来实现的
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

        //第一种方式（add），初始化fragment并添加到事务中，如果为null就new一个
        if(f1 == null){
           f1 = new Blank1Fragment();
            transaction.add(R.id.main_frame_layout,f1);
        }
        mImgWeixin.setImageResource(R.drawable.tab_weixin_pressed);
        //隐藏所有fragment
        hideFragment(transaction);
        //显示需要显示的fragment
        transaction.show(f1);

        //第二种方式(replace)，初始化fragment
//        if(f1 == null){
//            f1 = new MyFragment("消息");
//        }
//        transaction.replace(R.id.main_frame_layout, f1);

        //提交事务
        transaction.commit();
    }
    private void initFragment2(){
        //开启事务，fragment的控制是由事务来实现的
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

        //第一种方式（add），初始化fragment并添加到事务中，如果为null就new一个
        if(f2 == null){
            f2 = new Blank2Fragment("朋友");
            transaction.add(R.id.main_frame_layout, f2);
        }
        mImgFrd.setImageResource(R.drawable.tab_find_frd_pressed);
        //隐藏所有fragment
        hideFragment(transaction);
        //显示需要显示的fragment
        transaction.show(f2);

        transaction.commit();
    }
    private void initFragment3(){
        //开启事务，fragment的控制是由事务来实现的
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

        //第一种方式（add），初始化fragment并添加到事务中，如果为null就new一个
        if(f3 == null){
            f3 = new Blank3Fragment("通讯录");
            transaction.add(R.id.main_frame_layout, f3);
        }
        mImgAddress.setImageResource(R.drawable.tab_address_pressed);
        //隐藏所有fragment
        hideFragment(transaction);
        //显示需要显示的fragment
        transaction.show(f3);

        //第二种方式(replace)，初始化fragment
//        }
//        if(f1 == null){
//            f1 = new MyFragment("消息");
//        transaction.replace(R.id.main_frame_layout, f1);

        //提交事务
        transaction.commit();
    }
    private void initFragment4(){
        //开启事务，fragment的控制是由事务来实现的
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

        //第一种方式（add），初始化fragment并添加到事务中，如果为null就new一个
        if(f4 == null){
            f4 = new Blank4Fragment("设置");
            transaction.add(R.id.main_frame_layout, f4);
        }
        mImgSettings.setImageResource(R.drawable.tab_settings_pressed);
        //隐藏所有fragment
        hideFragment(transaction);
        //显示需要显示的fragment
        transaction.show(f4);

        //第二种方式(replace)，初始化fragment
//        if(f1 == null){
//            f1 = new MyFragment("消息");
//        }
//        transaction.replace(R.id.main_frame_layout, f1);

        //提交事务
        transaction.commit();
    }
    //隐藏所有的fragment
    private void hideFragment(FragmentTransaction transaction){
        if(f1 != null){
            transaction.hide(f1);
        }
        if(f2 != null){
            transaction.hide(f2);
        }
        if(f3 != null){
            transaction.hide(f3);
        }
        if(f4 != null){
            transaction.hide(f4);
        }
    }

    @Override
    public void onClick(View v) {
        resetimg();
        if(v == foot1){
            initFragment1();
        }else if(v == foot2){
            initFragment2();
        }else if(v == foot3){
            initFragment3();
        }else if(v == foot4){
            initFragment4();
        }
    }

    public void resetimg(){
        mImgWeixin.setImageResource(R.drawable.tab_weixin_normal);
        mImgFrd.setImageResource(R.drawable.tab_find_frd_normal);
        mImgAddress.setImageResource(R.drawable.tab_address_normal);
        mImgSettings.setImageResource(R.drawable.tab_settings_normal);

    }
}

运行结果展示：

 

 

 最后附上源码的代码仓库地址（码云）

 as: as项目代码仓库 - Gitee.com