android viewPager 轮播图

最新推荐文章于 2024-12-20 02:07:43 发布

原创最新推荐文章于 2024-12-20 02:07:43 发布 · 682 阅读

CC 4.0 BY-SA版权

本文介绍了一种在Android应用中实现轮播图的方法，通过使用ViewPager控件展示多个图片，并利用Handler更新当前显示的图片。同时，通过底部的小圆点指示当前图片的位置。

private ViewPagerAdapter mViewPagerAdapter;
private List<ImageView> images;
private List<View> dots;
private int currentItem;
private int oldPosition = 0; //记录上一次点的位置
private ScheduledExecutorService scheduledExecutorService;//线程池

private int[] imageIds = new int[]{
        R.drawable.viewpager_one,
        R.drawable.viewpager_one,
        R.drawable.viewpager_one,

};




/**
 * 接收子线程传递过来的数据
 */
private Handler mHandler = new Handler(){
    public void handleMessage(android.os.Message msg) {
        mHomeVp.setCurrentItem(currentItem);
    }
};

/**
 * 轮播监听   private ViewPager mHomeVp;  ui控件
 
 */mHomeVp.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {    @Override    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {    }    @Override    public void onPageSelected(int position) {        dots.get(position).setBackgroundResource(R.drawable.dot_focused);        dots.get(oldPosition).setBackgroundResource(R.drawable.dot_normal);        oldPosition = position;        currentItem = position;    }    @Override    public void onPageScrollStateChanged(int state) {    }});

private void initVariable()
{
    //显示的图片
    images = new ArrayList<ImageView>();
    for(int i = 0; i < imageIds.length; i++){
        ImageView imageView = new ImageView(getActivity());
        imageView.setBackgroundResource(imageIds[i]);
        images.add(imageView);
    }
    //显示的小点
    dots = new ArrayList<View>();
    dots.add(mView.findViewById(R.id.dot_0));
    dots.add(mView.findViewById(R.id.dot_1));
    dots.add(mView.findViewById(R.id.dot_2));


    mViewPagerAdapter = new ViewPagerAdapter();
    mHomeVp.setAdapter(mViewPagerAdapter);
}

    private class ViewPagerAdapter extends PagerAdapter
    {

        @Override
        public int getCount() {
            return images.size();
        }

        @Override
        public boolean isViewFromObject(View view, Object object) {

            return view == object;
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView(images.get(position));
//            super.destroyItem(container, position, object);
        }


        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            container.addView(images.get(position));
            return images.get(position);
        }



    }


    @Override
    public void onStart() {
        super.onStart();

        scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
        scheduledExecutorService.scheduleWithFixedDelay(
                new ViewPageTask(),
                2,
                3,
                TimeUnit.SECONDS);


    }

    private class ViewPageTask implements Runnable{

        @Override
        public void run() {
            currentItem = (currentItem + 1) % imageIds.length;
            mHandler.sendEmptyMessage(0);
        }
    }

XML:

<FrameLayout

    android:layout_width="match_parent"
    android:layout_height="121dp">

    <android.support.v4.view.ViewPager
        android:id="@+id/home_vp"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="35dip"
        android:layout_gravity="bottom"
        android:background="#33000000"
        android:gravity="center"
        android:orientation="vertical">

        <TextView
            android:id="@+id/home_vp_title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="图片标题"
            android:textColor="@android:color/white"/>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="3dip"
            android:orientation="horizontal">

            <View
                android:id="@+id/dot_0"
                android:layout_width="5dip"
                android:layout_height="5dip"
                android:layout_marginLeft="2dip"
                android:layout_marginRight="2dip"
                android:background="@drawable/dot_focused"/>

            <View
                android:id="@+id/dot_1"
                android:layout_width="5dip"
                android:layout_height="5dip"
                android:layout_marginLeft="2dip"
                android:layout_marginRight="2dip"
                android:background="@drawable/dot_normal"/>

            <View
                android:id="@+id/dot_2"
                android:layout_width="5dip"
                android:layout_height="5dip"
                android:layout_marginLeft="2dip"
                android:layout_marginRight="2dip"
                android:background="@drawable/dot_normal"/>


        </LinearLayout>
    </LinearLayout>
</FrameLayout>