int count = adapter.getCount(); 
if (count > 1) { // 多于1个，才循环 
  int index = viewPager.getCurrentItem(); 
  index = (index + 1) % count; 
  viewPager.setCurrentItem(index, true); 
}

public class MyAdapter extends PagerAdapter{  
  @Override  
  public int getCount() {  
    return Integer.MAX_VALUE;  
  }  
  @Override  
  public boolean isViewFromObject(View arg0, Object arg1) {  
    return arg0 == arg1;  
  }  
  @Override  
  public void destroyItem(View container, int position, Object object) {  
    ((ViewPager)container).removeView(mImageViews[position % count]);  
  }  
  public Object instantiateItem(View container, int position) {  
      View view = mImageViews[position % count]; 
    ((ViewPager)container).addView(view, 0);  
    return view;  
  }  
}  
protected void onCreate(Bundle savedInstanceState) {  
  viewPager.setAdapter(new MyAdapter());  
  //设置ViewPager的默认项, 设置为总数的100倍，一开始才能往左滑动  
  viewPager.setCurrentItem(count * 100);       
}  

public class AdapterCycle extends PagerAdapter  
    implements ViewPager.OnPageChangeListener{ 
  private Context mContext; // 上下文 
  private LayoutInflater mInflater; // 用于解XML 
  private LinkedList<View> mViews; // <span style="font-family: Arial, Helvetica, sans-serif;">用于</span><span style="font-family: Arial, Helvetica, sans-serif;">显示的View</span> 
  private List<Drawable> mList; // 数据源<span style="font-family: Arial, Helvetica, sans-serif;">Drawable</span> 
  private ViewPager mViewPager; //页面 
  public AdapterCycle(Context context, ViewPager viewPager,  
    List<Drawable> list) 
  { 
    mContext = context; 
    mInflater = LayoutInflater.from(context); 
    mViewPager = viewPager; 
    if (list != null) { 
      //无论是否多于1个，都要初始化第一个（index:0） 
      mViews = new LinkedList<View>(); 
      ImageView view = (ImageView) mInflater.inflate( 
          R.layout.activity_main_item_cycle, null); 
      Drawable drawable = list.get(list.size() - 1); 
      view.setImageDrawable(drawable); 
      mViews.add(view); 
      //注意，如果不只1个，mViews比mList多两个（头尾各多一个） 
      //假设：mList为mList[0~N-1], mViews为mViews[0~N+1] 
      // mViews[0]放mList[N-1], mViews[i]放mList[i-1], mViews[N+1]放mList[0] 
      // mViews[1~N]用于循环；首位之前的mViews[0]和末尾之后的mViews[N+1]用于跳转 
      // 首位之前的mViews[0]，跳转到末尾（N）；末位之后的mViews[N+1]，跳转到首位（1） 
      if( list.size() > 1) { //多于1个要循环 
        for (Drawable d : list) { //中间的N个（index:1~N） 
          ImageView v = (ImageView) mInflater.inflate( 
              R.layout.activity_main_item_cycle, null); 
          v.setImageDrawable(d); 
          mViews.add(v); 
        } 
        //最后一个（index:N+1） 
        view = (ImageView) mInflater.inflate( 
            R.layout.activity_main_item_cycle, null); 
        drawable = dList.get(0); 
        view.setImageDrawable(drawable); 
        mViews.add(view); 
      } 
    } 
  } 
  @Override 
  public int getCount() { 
    return mViews.size(); 
  } 
  @Override 
  public boolean isViewFromObject(View view, Object object) { 
    return view == object; 
  } 
  @Override 
  public void destroyItem(ViewGroup container, int position, Object object) { 
    ((ViewPager) container).removeView(mViews.get(position)); 
  } 
  @Override 
  public Object instantiateItem(ViewGroup container, int position) { 
    View view = mViews.get(position); 
    container.addView(view); 
    return view; 
  } 
  // 实现ViewPager.OnPageChangeListener接口 
  @Override 
  public void onPageSelected(int position) { 
    LogUtils.logi(TAG, "onPageSelected:" + position); 
    if ( mViews.size() > 1) { //多于1，才会循环跳转 
      if ( position < 1) { //首位之前，跳转到末尾（N） 
        position = mList.size(); //注意这里是mList，而不是mViews 
        mViewPager.setCurrentItem(position, false); 
      } else if ( position > mList.size()) { //末位之后，跳转到首位（1） 
        mViewPager.setCurrentItem(1, false); //false:不显示跳转过程的动画 
        position = 1; 
      } 
    }     
  } 
  @Override 
  public void onPageScrolled(int position, float positionOffset, 
      int positionOffsetPixels) { 
    // 什么都不干 
  } 
  @Override 
  public void onPageScrollStateChanged(int state) { 
    // 什么都不干 
  } 
} 
  //在外层，将mViewPager初始位置设置为1即可 
  if (mAdapterCycle.getCount() > 1) { //多于1个，才循环并开启定时器 
    mViewPager.setCurrentItem(1); //将mViewPager初始位置设置为1 
    startTimer(); //开启定时器，定时切换页面 
  } 

int count = adapter.getCount(); 
if (count > 2) { // 实际上，多于1个，就多于3个 
  int index = viewPager.getCurrentItem(); 
  index = index % (count - 2) + 1; //这里修改过 
  viewPager.setCurrentItem(index, true); 
}