Android开发之viewPager

定义：以滑动的格式显示视图或Fragment。建议使用viewPager

效果显示

1、三个layout布局

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#004587"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/layout1"
        android:text="layout_one"
        android:gravity="center"
        android:textSize="30dp"/>

</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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/teal_200"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/layout2"
        android:text="layout_two"
        android:gravity="center"
        android:textSize="30dp"/>

</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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/cardview_dark_background"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/layout3"
        android:text="layout_three"
        android:gravity="center"
        android:textSize="30dp"/>

</LinearLayout>

2、主页面布局（添加viewPager控件）

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <androidx.viewpager.widget.ViewPager
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/viewP"/>
</LinearLayout>

3、自定义Adapter，并继承PagerAdapter

package com.android.viewpaperexample;

import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import androidx.annotation.NonNull;
import androidx.viewpager.widget.PagerAdapter;
import java.util.List;

/**
 * date     :   2022/2/7 16:06
 */
public class MyAdapter extends PagerAdapter {
    private List<View> mListView;

    public MyAdapter(List<View> listView) {
        mListView = listView;
    }

    /**
     *返回可用的视图数
     * return the number of views available
     * @return
     */
    @Override
    public int getCount() {
        return mListView.size();
    }

    @Override
    public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
        return view == object;
    }

    /**
     * 将给定位置的view添加到ViewGroup中，创建并显示出来
     * @param container
     * @param position
     * @return
     */
    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, int position) {
        container.addView(mListView.get(position),0);
        return mListView.get(position);
    }

    /**
     * 销毁viewGroup中指定的view视图
     * @param container
     * @param position
     * @param object
     */
    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        container.removeView(mListView.get(position));
    }
}

4、在主Activity中进行逻辑书写

package com.android.viewpaperexample;

import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import java.util.ArrayList;
import java.util.List;

/**
 * 在此项目中实现viewPaper的功能。
 * 创建三个layout视图
 * 1、在主视图中引用ViewPaper控件，并获取控件
 * 2、自定义Adapter，并继承PagerAdapter
 * 3、将获取的view存入到List中
 * 4、viewPaper中设置Adapter
 */
public class MainActivity extends AppCompatActivity {
    private ViewPager mViewPager;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        /**
         * 通过如下方式，获取layout控件
         */
        LayoutInflater inflater = LayoutInflater.from(this);
        View layout1 = inflater.inflate(R.layout.layout1, null);
        View layout2 = inflater.inflate(R.layout.layout2, null);
        View layout3 = inflater.inflate(R.layout.layout3, null);
        /**
         * 创建一个List，并将获取的 view视图存入到List中
         */
        List<View> listView = new ArrayList<>();
        listView.add(layout1);
        listView.add(layout2);
        listView.add(layout3);
        /**
         *通过findViewById()获取viewPager,并设置Adapter
         */
        mViewPager = findViewById(R.id.viewP);
        MyAdapter myAdapter = new MyAdapter(listView);
        mViewPager.setAdapter(myAdapter);
    }
}