Android Handler的PostDelayed方法实现图片轮播 Android开发使用Handler的PostDelayed方法实现图片轮播功能

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
    }
}

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;
    }
}

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);
    }
  }
}