Android 使用Handler的PostDelayed方法实现图片的轮播

来源：互联网发布：cf手游刷神器软件编辑：程序博客网时间：2024/05/16 09:00

第一步：创建MainActivity类

    public class BaseActivity extends ActionBarActivity {        private List<String> mDatas;        private ViewPager mViewPager;        private boolean isRun = false;        private AutoRunTask mTask;        @Override        protected void onCreate(Bundle savedInstanceState) {            super.onCreate(savedInstanceState);            mViewPager = new ViewPager(this);            mViewPager.setLayoutParams(new AbsListView.LayoutParams(LayoutParams.MATCH_PARENT, Util                .getDimen(R.dimen.home_pic_height)));            mViewPager.setAdapter(new HomePagerAdapter());            // 设置滑动的初始位置            mViewPager.setCurrentItem(1000 * mDatas.size());            mViewPager.setOnTouchListener(this);            mTask = new AutoRunTask();            mTask.start();        }        @Override        public boolean onTouch(View v, MotionEvent event) {            switch (event.getAction()) {            case MotionEvent.ACTION_DOWN:                mTask.stop();                break;            case MotionEvent.ACTION_UP:            case MotionEvent.ACTION_CANCEL:                mTask.start();                break;            default:                break;            }            return false; //viewpager必须是false,如果是true是就不能移动        }   }

第二步：创建无限循环的PagerAdaper

class HomePagerAdapter extends PagerAdapter {        // 使用此对imageView进行复用        private LinkedList<ImageView> convertViews = new LinkedList<ImageView>();        @Override        public int getCount() {            // return mPicUrls.size();            return Integer.MAX_VALUE; // 可以无线滑动        }        @Override        public boolean isViewFromObject(View arg0, Object arg1) {            return arg0 == arg1;        }        @Override        public void destroyItem(ViewGroup container, int position, Object object) {            if (object != null && object instanceof ImageView) {                ImageView imageView = (ImageView) object;                // 添加到集合里                convertViews.add(imageView);                container.removeView(imageView);            }            super.destroyItem(container, position, object);        }        @Override        public Object instantiateItem(ViewGroup container, int position) {            // position 因为无线大，所以            int index = position % mDatas.size();            ImageView imageView = null;            if (convertViews != null && convertViews.size() > 0) {                // 取出一个imageView                imageView = convertViews.remove(0);            } else {                imageView = new ImageView(Util.getContext());            }            String uri = HttpHelper.URL + "image?name=" + mDatas.get(index);            mBitmapUtils.display(imageView, uri);            container.addView(imageView);            return imageView;        }    }

第三步：使用handler创建轮播类

public class AutoRunTask extends Handler implements Runnable {    @Override    public void run() {        while (isRun) {            removeCallbacks(this);            int currentItem = mViewPager.getCurrentItem();            currentItem++;            mViewPager.setCurrentItem(currentItem);            postDelayed(this, 2000);        }    }    public void start() {        if (!isRun) {            removeCallbacks(this);            isRun = true;            postDelayed(this, 2000);        }    }    public void stop() {        if (isRun) {            isRun = false;            removeCallbacks(this);        }    }}

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