组合控件——顶部导航栏——标签布局TabLayout

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布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
 
    <androidx.appcompat.widget.Toolbar
        android:id="@+id/tl_head"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        app:navigationIcon="@drawable/ic_back">
        <!-- 注意TabLayout节点需要使用完整路径 -->
        <com.google.android.material.tabs.TabLayout
            android:id="@+id/tab_title"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_centerInParent="true"
            app:tabIndicatorColor="@color/red"
            app:tabIndicatorHeight="2dp"
            app:tabSelectedTextColor="@color/red"
            app:tabTextColor="@color/grey"
            app:tabTextAppearance="@style/TabText" />
    </androidx.appcompat.widget.Toolbar>
 
    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="@color/grey" />
 
    <androidx.viewpager.widget.ViewPager
        android:id="@+id/vp_content"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
 
</LinearLayout>

<resources>
 
    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>
 
<!--    <style name="AppCompatTheme" parent="Theme.AppCompat.Light.NoActionBar">-->
<!--    </style>-->
 
    <style name="TabButton">
        <item name="android:layout_width">0dp</item>
        <item name="android:layout_height">match_parent</item>
        <item name="android:layout_weight">1</item>
        <item name="android:padding">5dp</item>
        <item name="android:gravity">center</item>
        <item name="android:background">@drawable/tab_bg_selector</item>
        <item name="android:textSize">12sp</item>
        <item name="android:textColor">@drawable/tab_text_selector</item>
        <item name="android:button">@null</item>
    </style>
 
    <style name="TabText">
        <item name="android:layout_width">match_parent</item>
        <item name="android:layout_height">match_parent</item>
        <item name="android:gravity">center</item>
        <item name="android:textSize">17sp</item>
        <item name="android:textColor">@drawable/toolbar_text_selector</item>
    </style>
 
</resources>

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_selected="true" android:color="@color/red" />
    <item android:color="@color/grey" />
</selector>

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#008577</color>
    <color name="colorPrimaryDark">#00574B</color>
    <color name="colorAccent">#D81B60</color>
    <color name="black">#000000</color>
    <color name="white">#ffffff</color>
    <color name="purple_200">#FFBB86FC</color>
    <color name="purple_500">#FF6200EE</color>
    <color name="purple_700">#FF3700B3</color>
    <color name="teal_200">#FF03DAC5</color>
    <color name="teal_700">#FF018786</color>
    <color name="tab_text_selected">#0084e8</color>
    <color name="tab_text_normal">#7597b3</color>
    <color name="blue_light">#aaaaff</color>
    <color name="grey">#888888</color>
    <color name="red">#ff0000</color>
</resources>

<resources>
    <string name="app_name">My Application</string>
    <string name="title_activity_main2">MainActivity2</string>
    <string name="title_home">Home</string>
    <string name="title_dashboard">Dashboard</string>
    <string name="title_notifications">Notifications</string>
    <string name="title_activity_main3">MainActivity3</string>
    <string name="title_activity_main4">MainActivity4</string>
    <string name="title_activity_main5">MainActivity5</string>
    <string name="menu_first">首页</string>
    <string name="menu_second">分类</string>
    <string name="menu_third">购物车</string>
    <string name="book_name">Android Studio开发实战\n从零基础到App上线</string>
</resources>

package com.example.myapplication.fragment;
 
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.fragment.app.Fragment;
import com.example.myapplication.R;
 
public class BookDetailFragment extends Fragment
{
    
    protected View mView; // 声明一个视图对象
    protected Context mContext; // 声明一个上下文对象
 
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
    {
        
        mContext = getActivity(); // 获取活动页面的上下文
        
        // 根据布局文件fragment_book_detail.xml生成视图对象
        mView = inflater.inflate(R.layout.fragment_book_detail, container, false);
        
        return mView;
    }
 
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
 
    <ImageView
        android:id="@+id/iv_book_detail"
        android:layout_width="match_parent"
        android:layout_height="360dp"
        android:layout_marginTop="5dp"
        android:scaleType="fitCenter"
        android:src="@drawable/book_detail" />
 
    <TextView
        android:id="@+id/tv_book_detail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="0dp"
        android:gravity="center"
        android:text="@string/book_name"
        android:textColor="@color/black"
        android:textSize="20sp" />
 
</LinearLayout>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
 
    <ImageView
        android:id="@+id/iv_book_cover"
        android:layout_width="match_parent"
        android:layout_height="360dp"
        android:layout_marginTop="5dp"
        android:scaleType="fitCenter"
        android:src="@drawable/book_cover" />
 
    <TextView
        android:id="@+id/tv_book_cover"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="0dp"
        android:gravity="center"
        android:text="@string/book_name"
        android:textColor="@color/black"
        android:textSize="20sp" />
 
</LinearLayout>

package com.example.myapplication.fragment;
 
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
 
import androidx.fragment.app.Fragment;
 
import com.example.myapplication.R;
 
public class BookCoverFragment extends Fragment 
{
    protected View mView; // 声明一个视图对象
    protected Context mContext; // 声明一个上下文对象
    
 
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
    {
        mContext = getActivity(); // 获取活动页面的上下文
        
        // 根据布局文件fragment_book_cover.xml生成视图对象
        mView = inflater.inflate(R.layout.fragment_book_cover, container, false);
        
        return mView;
    }
 
}

package com.example.myapplication.adapter;
 
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentPagerAdapter;
 
import com.example.myapplication.fragment.BookCoverFragment;
import com.example.myapplication.fragment.BookDetailFragment;
 
public class GoodsPagerAdapter extends FragmentPagerAdapter {
    private String[] mTitleArray; // 声明一个标题文字数组
 
    // 碎片页适配器的构造方法，传入碎片管理器与标题列表
    public GoodsPagerAdapter(FragmentManager fm, String[] titleArray) {
        super(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
        mTitleArray = titleArray;
    }
 
    // 获取指定位置的碎片Fragment
    public Fragment getItem(int position) {
        if (position == 0) { // 第一页展示书籍封面
            return new BookCoverFragment();
        } else if (position == 1) { // 第二页展示书籍详情
            return new BookDetailFragment();
        }
        return new BookCoverFragment();
    }
 
    // 获取碎片Fragment的个数
    public int getCount() {
        return mTitleArray.length;
    }
 
    // 获得指定碎片页的标题文本
    public CharSequence getPageTitle(int position) {
        return mTitleArray[position];
    }
}

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto" >
 
    <item
        android:id="@+id/menu_refresh"
        android:icon="@drawable/ic_refresh"
        app:showAsAction="ifRoom"
        android:title="刷新"/>
 
    <item
        android:id="@+id/menu_about"
        android:icon="@drawable/ic_about"
        app:showAsAction="never"
        android:title="关于"/>
    
    <item
        android:id="@+id/menu_quit"
        android:icon="@drawable/ic_quit"
        app:showAsAction="never"
        android:title="退出"/>
    
    
</menu>

package com.example.myapplication;
 
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.viewpager.widget.ViewPager;
import com.example.myapplication.adapter.GoodsPagerAdapter;
import com.example.myapplication.widget.DateUtil;
import com.google.android.material.tabs.TabLayout;
 
@SuppressLint("SetTextI18n")
public class MainActivity extends AppCompatActivity implements TabLayout.OnTabSelectedListener
{
    private final static String TAG = "TabLayoutActivity";
    private ViewPager vp_content; // 声明一个翻页视图对象
    private TabLayout tab_title; // 声明一个标签布局对象
    private String[] mTitleArray = {"商品", "详情"}; // 标题文字数组
 
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        Toolbar tl_head = findViewById(R.id.tl_head); // 从布局文件中获取名叫tl_head的工具栏
        tl_head.setTitle(""); // 设置工具栏的标题文本
        tab_title = findViewById(R.id.tab_title); // 从布局文件中获取名叫tab_title的标签布局
        vp_content = findViewById(R.id.vp_content); // 从布局文件中获取名叫vp_content的翻页视图
        initTabLayout(); // 初始化标签布局
        initTabViewPager(); // 初始化标签翻页
    }
 
    // 初始化标签布局
    private void initTabLayout() {
        // 给标签布局添加一个文字标签
        tab_title.addTab(tab_title.newTab().setText(mTitleArray[0]));
        // 给标签布局添加一个文字标签
        tab_title.addTab(tab_title.newTab().setText(mTitleArray[1]));
        tab_title.addOnTabSelectedListener(this); // 给标签布局添加标签选中监听器
        // 监听器ViewPagerOnTabSelectedListener允许直接关联某个翻页视图
        //tab_title.addOnTabSelectedListener(new ViewPagerOnTabSelectedListener(vp_content));
    }
 
    // 初始化标签翻页
    private void initTabViewPager() {
        // 构建一个商品信息的翻页适配器
        GoodsPagerAdapter adapter = new GoodsPagerAdapter(
                getSupportFragmentManager(), mTitleArray);
        vp_content.setAdapter(adapter); // 设置翻页视图的适配器
        // 给vp_content添加页面变更监听器
        vp_content.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {
                tab_title.getTabAt(position).select(); // 选中指定位置的标签
            }
        });
    }
 
    // 在标签被重复选中时触发
    public void onTabReselected(TabLayout.Tab tab) {}
 
    // 在标签选中时触发
    public void onTabSelected(TabLayout.Tab tab) {
        vp_content.setCurrentItem(tab.getPosition()); // 设置翻页视图显示第几页
    }
 
    // 在标签取消选中时触发
    public void onTabUnselected(TabLayout.Tab tab) {}
 
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // 从menu_overflow.xml中构建菜单界面布局
        getMenuInflater().inflate(R.menu.menu_overflow, menu);
        return true;
    }
 
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == android.R.id.home) { // 点击了工具栏左边的返回箭头
            finish(); // 结束当前页面
        } else if (id == R.id.menu_refresh) { // 点击了刷新图标
            Toast.makeText(this, "当前刷新时间: " + DateUtil.getNowDateTime("yyyy-MM-dd HH:mm:ss")
                    , Toast.LENGTH_LONG).show();
            return true;
        } else if (id == R.id.menu_about) { // 点击了关于菜单项
            Toast.makeText(this, "这个是标签布局的演示demo", Toast.LENGTH_LONG).show();
            return true;
        } else if (id == R.id.menu_quit) { // 点击了退出菜单项
            finish(); // 结束当前页面
        }
        return super.onOptionsItemSelected(item);
    }
 
}