Android中viewPager实现欢迎引导

public class MainActivity extends Activity implements OnClickListener, OnPageChangeListener{ private ViewPager vp;    private ViewPagerAdapter vpAdapter;    private List<View> views;    private int lastValue = -1;    private Bitmap bitmap;        //引导图片资源    private static final int[] pics = { R.drawable.guide1,            R.drawable.guide2, R.drawable.guide3,            R.drawable.guide4,R.drawable.guide5 };        //底部小店图片    private ImageView[] dots ;        //记录当前选中位置    private int currentIndex;        /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                views = new ArrayList<View>();               LinearLayout.LayoutParams mParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,                LinearLayout.LayoutParams.WRAP_CONTENT);                //初始化引导图片列表        for(int i=0; i<pics.length; i++) {            ImageView iv = new ImageView(this);            iv.setLayoutParams(mParams);            iv.setImageBitmap(getBitmap(pics[i]));            views.add(iv);        }        vp = (ViewPager) findViewById(R.id.viewpager);        //初始化Adapter        vpAdapter = new ViewPagerAdapter(views);        vp.setAdapter(vpAdapter);        //绑定回调        vp.setOnPageChangeListener(this);                //初始化底部小点        initDots();            }    /**     * 以最小内存获取资源图片     * @param resId     * @return     */    private Bitmap getBitmap(int resId){    BitmapFactory.Options opt = new BitmapFactory.Options();    opt.inPreferredConfig = Bitmap.Config.RGB_565;    opt.inPurgeable = true;    opt.inInputShareable = true;    InputStream is = this.getResources().openRawResource(resId);    bitmap = BitmapFactory.decodeStream(is, null, opt);    return bitmap;    }    private void initDots() {        LinearLayout ll = (LinearLayout) findViewById(R.id.ll);        dots = new ImageView[pics.length];        //循环取得小点图片        for (int i = 0; i < pics.length; i++) {            dots[i] = (ImageView) ll.getChildAt(i);            dots[i].setEnabled(true);//都设为灰色            dots[i].setOnClickListener(this);            dots[i].setTag(i);//设置位置tag，方便取出与当前位置对应        }        currentIndex = 0;        dots[currentIndex].setEnabled(false);//设置为白色，即选中状态    }        /**     *设置当前的引导页      */    private void setCurView(int position)    {        if (position < 0 || position >= pics.length) {            return;        }        vp.setCurrentItem(position);    }    /**     *这只当前引导小点的选中      */    private void setCurDot(int positon)    {        if (positon < 0 || positon > pics.length - 1 || currentIndex == positon) {            return;        }        dots[positon].setEnabled(false);        dots[currentIndex].setEnabled(true);        currentIndex = positon;    }    //当滑动状态改变时调用    @Override    public void onPageScrollStateChanged(int arg0) {          if(arg0 == 0){           if(lastValue == pics.length-1){           Toast.makeText(this, "已经是最后一张了", Toast.LENGTH_SHORT).show();           }           }            }    //当当前页面被滑动时调用    @Override    public void onPageScrolled(int arg0, float arg1, int arg2) {    lastValue = arg0;    }    //当新的页面被选中时调用    @Override    public void onPageSelected(int arg0) {        //设置底部小点选中状态        setCurDot(arg0);    }    @Override    public void onClick(View v) {        int position = (Integer)v.getTag();        setCurView(position);        setCurDot(position);    }}public class ViewPagerAdapter extends PagerAdapter { //界面列表    private List<View> views;        public ViewPagerAdapter (List<View> views){        this.views = views;    }    //销毁arg1位置的界面    @Override    public void destroyItem(View arg0, int arg1, Object arg2) {        ((ViewPager) arg0).removeView(views.get(arg1));            }    @Override    public void finishUpdate(View arg0) {        // TODO Auto-generated method stub            }    //获得当前界面数    @Override    public int getCount() {        if (views != null)        {            return views.size();        }                return 0;    }        //初始化arg1位置的界面    @Override    public Object instantiateItem(View arg0, int arg1) {                ((ViewPager) arg0).addView(views.get(arg1), 0);                return views.get(arg1);    }    //判断是否由对象生成界面    @Override    public boolean isViewFromObject(View arg0, Object arg1) {        return (arg0 == arg1);    }    @Override    public void restoreState(Parcelable arg0, ClassLoader arg1) {        // TODO Auto-generated method stub            }    @Override    public Parcelable saveState() {        // TODO Auto-generated method stub        return null;    }    @Override    public void startUpdate(View arg0) {        // TODO Auto-generated method stub            }}