Android开发实现广告无限循环功能示例

/**
 * 新闻首页
 *
 * @Project App_Card
 * @Package com.android.koomama.fragment.home
 * @author chenlin
 * @version 1.0
 * @Date 2014年6月22日
 * @Note TODO
 */
public class NewsHomeFragment extends BaseFragment implements OnTouchListener {
  private ImageHandler mHandler = new ImageHandler(new WeakReference(this));
  private ViewPager mViewPager;
  // 自定义轮播图的资源
  private int[] mImageResIds = { R.drawable.img1, R.drawable.img2, R.drawable.img3, R.drawable.img4, R.drawable.img5 };
  // 放轮播图片的ImageView 的list
  private List mImageList = new ArrayList();
  // 放圆点的View的list
  private List mDotList = new ArrayList();
  @Override
  public View initConvertView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_news_main, container, false);
  }
  @Override
  protected void onVisible(boolean isInit) {
    if (isInit) {
      initViews();
    }
  }
  private void initViews() {
    // 初始化iewPager的内容
    mViewPager = (ViewPager) mConvertView.findViewById(R.id.view_pager);
    LinearLayout dotLayout = (LinearLayout) mConvertView.findViewById(R.id.dotLayout);
    dotLayout.removeAllViews();
    for (int i = 0; i < mImageResIds.length; i++) {
      ImageView imageView = new ImageView(getActivity());
      imageView.setScaleType(ScaleType.FIT_XY);
      // view.setTag(mImageResId[i]);
      imageView.setImageResource(mImageResIds[i]);
      mImageList.add(imageView);
      View dotView = new View(getActivity());
      LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(getResources().getDimensionPixelSize(R.dimen.dot_width),
          getResources().getDimensionPixelSize(R.dimen.dot_width));
      params.setMargins(4, 0, 4, 0);
      dotView.setLayoutParams(params);
//     if (i == 0) {
//       dotView.setBackgroundResource(R.drawable.dot_red);
//     } else {
//       dotView.setBackgroundResource(R.drawable.dot_gray);
//     }
      dotLayout.addView(dotView);
      mDotList.add(dotView);
    }
    mViewPager.setAdapter(new ImageAdapter(mImageList));
    mViewPager.setOnPageChangeListener(new PageChangeListener());
    mViewPager.setFocusable(true);
    mViewPager.setCurrentItem(Integer.MAX_VALUE / 2);// 默认在中间，使用户看不到边界
    mViewPager.setOnTouchListener(this);
    // 开始轮播效果
    mHandler.sendEmptyMessageDelayed(ImageHandler.MSG_UPDATE_IMAGE, ImageHandler.MSG_DELAY);
  }
  @Override
  public boolean onTouch(View v, MotionEvent event) {
    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
      mHandler.sendEmptyMessage(ImageHandler.MSG_KEEP_SILENT);
      break;
    case MotionEvent.ACTION_UP:
    case MotionEvent.ACTION_CANCEL:
      mHandler.sendEmptyMessageDelayed(ImageHandler.MSG_UPDATE_IMAGE, ImageHandler.MSG_DELAY);
      break;
    }
    return false;
  }
  private class PageChangeListener implements OnPageChangeListener {
    // 配合Adapter的currentItem字段进行设置。
    @Override
    public void onPageSelected(int position) {
      // 这个是设置左滑切换底部view的边界，必须要设置
      App.getInstance().setBorderViewPosition(position);
      mHandler.sendMessage(Message.obtain(mHandler, ImageHandler.MSG_PAGE_CHANGED, position, 0));
    }
    @Override
    public void onPageScrolled(int position, float arg1, int arg2) {
    }
    // 覆写该方法实现轮播效果的暂停和恢复
    @Override
    public void onPageScrollStateChanged(int state) {
      switch (state) {
      case ViewPager.SCROLL_STATE_DRAGGING:
        mHandler.sendEmptyMessage(ImageHandler.MSG_KEEP_SILENT);
        break;
      case ViewPager.SCROLL_STATE_IDLE:
        mHandler.sendEmptyMessageDelayed(ImageHandler.MSG_UPDATE_IMAGE, ImageHandler.MSG_DELAY);
        break;
      default:
        break;
      }
    }
  }
  private class ImageAdapter extends PagerAdapter {
    private List viewlist;
    public ImageAdapter(List viewlist) {
      this.viewlist = viewlist;
    }
    @Override
    public int getCount() {
      // 设置成最大，使用户看不到边界
      return Integer.MAX_VALUE;
    }
    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {
      return arg0 == arg1;
    }
    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
      // Warning：不要在这里调用removeView
    }
    @Override
    public Object instantiateItem(ViewGroup container, int position) {
      // 对ViewPager页号求模取出View列表中要显示的项
      position %= viewlist.size();
      if (position < 0) {
        position = viewlist.size() + position;
      }
      ImageView view = viewlist.get(position);
      // 如果View已经在之前添加到了一个父组件，则必须先remove，否则会抛出IllegalStateException。
      ViewParent vp = view.getParent();
      if (vp != null) {
        ViewGroup parent = (ViewGroup) vp;
        parent.removeView(view);
      }
      container.addView(view);
      // 此处可添加监听事件
      return view;
    }
  }
  private static class ImageHandler extends Handler {
    /**
     * 请求更新显示的View。
     */
    protected static final int MSG_UPDATE_IMAGE = 1;
    /**
     * 请求暂停轮播。
     */
    protected static final int MSG_KEEP_SILENT = 2;
    /**
     * 请求恢复轮播。
     */
    protected static final int MSG_BREAK_SILENT = 3;
    /**
     * 记录最新的页号，当用户手动滑动时需要记录新页号，否则会使轮播的页面出错。
     * 例如当前如果在第一页，本来准备播放的是第二页，而这时候用户滑动到了末页，
     * 则应该播放的是第一页，如果继续按照原来的第二页播放，则逻辑上有问题。
     */
    protected static final int MSG_PAGE_CHANGED = 4;
    // 轮播间隔时间
    protected static final long MSG_DELAY = 3000;
    // 使用弱引用避免Handler泄露.这里的泛型参数可以不是Activity，也可以是Fragment等
    private WeakReference weakReference;
    private int currentItem = 0;
    // private boolean isOnce = true;
    protected ImageHandler(WeakReference wk) {
      weakReference = wk;
    }
    @Override
    public void handleMessage(Message msg) {
      super.handleMessage(msg);
      final NewsHomeFragment fragment = weakReference.get();
      if (fragment == null) {
        // Activity已经回收，无需再处理UI了
        return;
      }
      // 第一次不删重复的消息
      if (currentItem != 0) {
        // 检查消息队列并移除未发送的消息，这主要是避免在复杂环境下消息出现重复等问题。
        if (fragment.mHandler.hasMessages(MSG_UPDATE_IMAGE)) {
          fragment.mHandler.removeMessages(MSG_UPDATE_IMAGE);
        }
      }
      switch (msg.what) {
      case MSG_UPDATE_IMAGE:
        currentItem++;
        fragment.mViewPager.setCurrentItem(currentItem);
        // 准备下次播放
        fragment.mHandler.sendEmptyMessageDelayed(MSG_UPDATE_IMAGE, MSG_DELAY);
        break;
      case MSG_KEEP_SILENT:
        // 只要不发送消息就暂停了
        break;
      case MSG_BREAK_SILENT:
        fragment.mHandler.sendEmptyMessageDelayed(MSG_UPDATE_IMAGE, MSG_DELAY);
        break;
      case MSG_PAGE_CHANGED:
        // 记录当前的页号，避免播放的时候页面显示不正确。
        int position = msg.arg1;
        int lastIndex = 0;
        int index = position % fragment.mImageList.size();
        for (int i = 0; i < fragment.mDotList.size(); i++) {
          fragment.mDotList.get(i).setBackgroundResource(R.drawable.dot_normal);
        }
        if (fragment.mDotList.get(index)!=null) {
          fragment.mDotList.get(index).setBackgroundResource(R.drawable.dot_red);
        }
        lastIndex = index;
        currentItem = position;
        break;
      default:
        break;
      }
    }
  }
}