本文實(shí)例講述了Android開(kāi)發(fā)使用Handler的PostDelayed方法實(shí)現(xiàn)圖片輪播功能。分享給大家供大家參考,具體如下:
第一步:創(chuàng)建MainActivity類(lèi)
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()); // 設(shè)置滑動(dòng)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必須是false,如果是true是就不能移動(dòng) }}第二步:創(chuàng)建無(wú)限循環(huán)的PagerAdaper
class HomePagerAdapter extends PagerAdapter { // 使用此對(duì)imageView進(jìn)行復(fù)用 private LinkedList<ImageView> convertViews = new LinkedList<ImageView>(); @Override public int getCount() { // return mPicUrls.size(); return Integer.MAX_VALUE; // 可以無(wú)線(xiàn)滑動(dòng) } @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?yàn)闊o(wú)線(xiàn)大,所以 int index = position % mDatas.size(); ImageView imageView = null; if (convertViews != null && convertViews.size() > 0) { // 取出一個(gè)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創(chuàng)建輪播類(lèi)
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); } }}希望本文所述對(duì)大家Android程序設(shè)計(jì)有所幫助。
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