Android实现图片自动切换

在Android中图片的自动切换不仅可以实现自动切换，而且还可以使用手动切换。而且一般在切换的时候，在图片下方还带有其他内容的切换，用来标记是第几个图片的切换。
实现效果如下：

具体的示例代码如下：
布局代码：

<?xml version="1.0" encoding="utf-8"?>
<ScrollView
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="250dp"
            android:padding="20dp"
            android:orientation="vertical">
            <androidx.viewpager.widget.ViewPager
                android:id="@+id/viewContent"
                android:layout_width="match_parent"
                android:layout_height="match_parent"/>
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="25dp"
                android:orientation="horizontal"
                android:layout_gravity="bottom"
                android:gravity="center"
                android:layout_marginTop="5dp"
                android:background="#E6E6E6">
                <View
                    android:id="@+id/p1"
                    android:layout_width="5dp"
                    android:layout_height="5dp"
                    android:layout_marginLeft="2dp"
                    android:layout_marginRight="2dp"
                    android:background="@drawable/dot_focus"/>
                <View
                    android:id="@+id/p2"
                    android:layout_width="5dp"
                    android:layout_height="5dp"
                    android:layout_marginLeft="2dp"
                    android:layout_marginRight="2dp"
                    android:background="@drawable/dot_normal"/>
                <View
                    android:id="@+id/p3"
                    android:layout_width="5dp"
                    android:layout_height="5dp"
                    android:layout_marginLeft="2dp"
                    android:layout_marginRight="2dp"
                    android:background="@drawable/dot_normal"/>
            </LinearLayout>
        </FrameLayout>
    </RelativeLayout>
</ScrollView

dot_focus.xml文件代码如下：

<?xml version="1.0" encoding="utf-8"?>
<shape android:shape="oval"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <corners android:radius="5dp"/>
    <solid android:color="@color/white"/>
</shape>

dot_normal.xml文件代码如下：

<?xml version="1.0" encoding="utf-8"?>
<shape android:shape="oval"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <corners android:radius="5dp"/>
    <solid android:color="@color/blue"/>
</shape>

Activity代码：

public class MainActivity extends AppCompatActivity {

    private ArrayList<ImageView> imageViews= new ArrayList<>();
    private ArrayList<View>dots=new ArrayList<>();
    private ViewPager vp;
    private int image[]={R.drawable.denglu,R.drawable.disanye,R.drawable.hhh};
    private int oldPosition=0;
    private int currentItem;
    private ScheduledExecutorService scheduledExecutorService;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取图片资源
        for (int i=0;i<image.length;i++){
            ImageView imageView=new ImageView(this);
            imageView.setImageResource(image[i]);
            imageViews.add(imageView);
        }
       //显示的点的集合
        dots.add(findViewById(R.id.p1));
        dots.add(findViewById(R.id.p2));
        dots.add(findViewById(R.id.p3));

        vp=findViewById(R.id.viewContent);
        vp.setAdapter(new ViewPagerAdapter());
        vp.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                //点的效果切换
                dots.get(oldPosition).setBackgroundResource(R.drawable.dot_normal);
                dots.get(position).setBackgroundResource(R.drawable.dot_fouced);
                oldPosition=position;
                currentItem=position;
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

    class ViewPagerAdapter extends PagerAdapter {
        @Override
        public int getCount() {
            return imageViews.size();
        }

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

        @Override
        public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
            View v=imageViews.get(position);
            container.removeView(v);
        }

        @NonNull
        @Override
        public Object instantiateItem(@NonNull ViewGroup container, int position) {
            View v=imageViews.get(position);
            container.addView(v);
            return v;
        }
    }

    @Override
    protected void onStart() {
        super.onStart();
        scheduledExecutorService= Executors.newSingleThreadScheduledExecutor();
        scheduledExecutorService.scheduleWithFixedDelay(new ViewPagerTask(),2,2, TimeUnit.SECONDS);
    }
    class ViewPagerTask implements Runnable{

        @Override
        public void run() {
            currentItem=(currentItem+1)%image.length;
            handler.obtainMessage().sendToTarget();
        }
    }
    Handler handler=new Handler(){
        @Override
        public void handleMessage(@NonNull Message msg) {
            vp.setCurrentItem(currentItem);
        }
    };
}