viewpage轮播图

<androidx.constraintlayout.widget.ConstraintLayout 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.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="160dp" >

        <androidx.viewpager.widget.ViewPager
            android:id="@+id/viewpager"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

        <LinearLayout

            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_alignParentBottom="true"
            android:background="#66000000"
            android:gravity="center_horizontal"
            android:orientation="vertical"
            android:padding="5dp"
            app:layout_constraintBottom_toBottomOf="@+id/viewpager">

            <TextView
                android:id="@+id/tv_desc"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:singleLine="true"
                android:text="社会"
                android:textColor="@android:color/white" />
            <LinearLayout
                android:id="@+id/ll_point_container"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginTop="5dp"
                android:orientation="horizontal"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent" />

        </LinearLayout>

    </androidx.constraintlayout.widget.ConstraintLayout>




</androidx.constraintlayout.widget.ConstraintLayout>

public class MainActivity extends AppCompatActivity implements ViewPager.OnPageChangeListener {


    private ViewPager viewPager;
    private int[] imageResIds;
    private ArrayList<ImageView> imageViewList;
    private ArrayList<View> pointViews;
    private LinearLayout ll_point_container;
    private String[] contentDesc;
    private TextView tv_desc;
    private int lastEnablePoint = 0;
    private boolean isRunning = true;
    private  Handler handler;
    private Runnable runnable;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 初始化布局 View 视图
        initViews();

        // Model 数据
        initData();

        // Controller 控制器
        initAdapter();
        //1.
         handler = new Handler();
       runnable= new Runnable() {
            @Override
            public void run() {

                viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
                handler.postDelayed(this, 2000);
            }

        };

       //2
//        mTimer.schedule(mTimerTask, 2000, 2000);
       //3
//        handler.postDelayed( runnable, 2000 );
        //开启轮询
//        new Thread() {
//            public void run() {
//                while(isRunning) {
//                    try {
//                        Thread.sleep(2000);
//                    } catch (InterruptedException e) {
//                        e.printStackTrace();
//                    }
//                    //往下跳一位
//                    runOnUiThread(new Runnable() {
//                        @Override
//                        public void run() {
//                            viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
//                        }
//                    });
//                }
//
//            }
//        }.start();

    }

    @Override
    protected void onPause() {
        super.onPause();
        handler.removeCallbacksAndMessages( null );

    }

    @Override
    protected void onResume() {
        super.onResume();
        handler.postDelayed( runnable, 2000 );
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        isRunning = false;
    }

    private void initViews() {
        viewPager = (ViewPager) findViewById(R.id.viewpager);
        viewPager.setOnPageChangeListener(this);// 设置滚动更新

        viewPager.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                    case MotionEvent.ACTION_MOVE:
                        handler.removeCallbacksAndMessages( null );
                        break;
                    case MotionEvent.ACTION_UP:
                        handler.postDelayed( runnable, 2000 );
                        break;
                }
                return false;
            }
        });
        tv_desc = (TextView) findViewById(R.id.tv_desc);

        ll_point_container =  findViewById(R.id.ll_point_container);

    }

    private void initAdapter() {
        ll_point_container.getChildAt(0).setEnabled(true);
        tv_desc.setText(contentDesc[0]);
        // 设置适配器
        viewPager.setAdapter(new MyAdapter());

        //默认设置到中间的某个位置
        int pos = Integer.MAX_VALUE / 2;
        //viewPager.setCurrentItem(pos - 3);
        viewPager.setCurrentItem(0);
    }

    private void initData() {

        // 初始化要显示的数据
        // 图片资源id数组
        imageResIds = new int[] { R.drawable.lunbo1, R.drawable.lunbo2, R.drawable.lunbo3,
                R.drawable.lunbo4};
        // 文本描述
        contentDesc = new String[] { "巩俐不低俗，我就不能低俗", "朴树又回来啦！再唱经典老歌引万人大合唱",
                "揭秘北京电影如何升级", "乐视网TV版大派送", "热血屌丝的反杀" };
        imageViewList = new ArrayList<ImageView>();
        pointViews = new ArrayList<View>();
        ImageView imageView;
        View pointView;
        LinearLayout.LayoutParams layoutParams;
        for (int i = 0; i < imageResIds.length; i++) {
            imageView = new ImageView(this);
            imageView.setBackgroundResource(imageResIds[i]);
            imageViewList.add(imageView);

            // 加小白点，指示器
            pointView = new View(this);
            pointView.setBackgroundResource(R.drawable.select);
            layoutParams = new LinearLayout.LayoutParams(7, 7);
            if (i != 0) {
                layoutParams.leftMargin = 10;
            }
            pointView.setEnabled(false);

            ll_point_container.addView(pointView, layoutParams);
        }

    }

    class MyAdapter extends PagerAdapter {

        @Override
        public int getCount() {
            return Integer.MAX_VALUE;
        }

        // 3、指定复用的判断逻辑
        @Override
        public boolean isViewFromObject(View view, Object object) {
            // 当滑到新的条目，又返回来，view是否可以被复用
            return view == object;
        }

        // 1、返回要显示的条目内容，创建条目
        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            // container：容器：ViewPager
            // position：当前要显示的条目的位置
            position = position % 4;

            ImageView imageView = imageViewList.get(position);

            // a、把view对象添加到container中
            container.addView(imageView);
            // b、把view对象返回给框架，适配器
            return imageView; // 必须要重写，否则抛异常
        }

        // 2、销毁条目
        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            // object 要销毁的对象
            container.removeView((View) object);
        }

    }

    @Override
    public void onPageScrolled(int position, float positionOffset,
                               int positionOffsetPixels) {

        // 滚动时调用
    }

    @Override
    public void onPageSelected(int position) {
        // 新条目被选中时调用
        position = position % 4;

        tv_desc.setText(contentDesc[position]);
        // 把之前的禁用，把最新的启用
        ll_point_container.getChildAt(lastEnablePoint).setEnabled(false);
        ll_point_container.getChildAt(position).setEnabled(true);
        lastEnablePoint = position;
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        // 滚动状态变化时调用


    }
}

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval" >

    <corners android:radius="5dp" />
    <solid android:color="@android:color/white" />

</shape>

<shape xmlns:android="http://schemas.android.com/apk/res/android"  android:shape="oval" >

    <corners android:radius="5dp" />
    <solid android:color="@android:color/darker_gray" />

</shape>

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_enabled="true" android:drawable="@drawable/shap1"></item>
    <item android:state_enabled="false" android:drawable="@drawable/shap2"></item>
</selector>