Android使用ViewPager做无限轮播，人为滑动时停止

Android使用ViewPager做无限轮播，人为滑动时停止"/>

Android使用ViewPager做无限轮播，人为滑动时停止

实现无限循环

使用取模，获取到当前图片所在的位置。

    private class MyPagerAdapter extends PagerAdapter {private Context context;List<ImageView> list;public MyPagerAdapter(Context context, List<ImageView> list) {this.context = context;this.list = list;}@Overridepublic int getCount() {//使用Integer的最大值，这样基本上就不需要滑动到最后了//除非用户很蛋疼return Integer.MAX_VALUE;}@Overridepublic Object instantiateItem(ViewGroup container, int position) {//当前位置模上总数等于图片在数组中的位置position %= list.size();if (position < 0) {position = list.size() + position;}ImageView imageView = list.get(position);//设置轮播点击事件final int finalPosition = position;imageView.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {Intent intent = new Intent(getApplicationContext(), BannerActivity.class);intent.putExtra("position", finalPosition);startActivity(intent);}});ViewGroup parent = (ViewGroup) imageView.getParent();if (parent != null) {parent.removeView(imageView);}container.addView(imageView);return list.get(position);}@Overridepublic boolean isViewFromObject(View view, Object object) {return object == view;}@Overridepublic void destroyItem(ViewGroup container, int position, Object object) {//注意这里不要使用//container.removeView(list.get(position));}}

自动循环实现

使用Handler每隔5秒一次消息，接收到轮播的动作就继续发一次消息，实现自动轮播的效果。

    private class MyHandler extends Handler {private Context context;//使用弱引用，避免handler造成内存泄露private WeakReference<MainActivity> weakReference;public MyHandler(WeakReference<MainActivity> weakReference) {this.weakReference = weakReference;}@Overridepublic void handleMessage(Message msg) {MainActivity activity = weakReference.get();//Activity不存在了，就不需要再处理了if (activity == null) {return;}//如果已经有消息了，先移除消息if (activity.handler.hasMessages(BANNER_NEXT)) {activity.handler.removeMessages(BANNER_NEXT);}switch (msg.what) {case BANNER_NEXT://跳到下一页，int currentItem = vpBanner.getCurrentItem();activity.vpBanner.setCurrentItem(++currentItem);//5秒后继续轮播activity.handler.sendEmptyMessageDelayed(BANNER_NEXT, 5000);break;case BANNER_PAUSE://暂停,不需要做任务操作break;case BANNER_RESUME://继续轮播activity.handler.sendEmptyMessageDelayed(BANNER_NEXT, 5000);break;}}}

在Activity中使用

        //这里放了3张图片，使用Gilde加载ImageView imageView1 = new ImageView(this);ImageView imageView2 = new ImageView(this);ImageView imageView3 = new ImageView(this);RequestManager requestManager = Glide.with(this);requestManager.load("=3251910782,1174316217&fm=21&gp=0.jpg").into(imageView1);requestManager.load(".jpg").into(imageView2);requestManager.load(".jpg").into(imageView3);List<ImageView> list = new ArrayList<>();list.add(imageView1);list.add(imageView2);list.add(imageView3);MyPagerAdapter adapter = new MyPagerAdapter(this, list);vpBanner = (ViewPager) findViewById(R.id.vpBanner);vpBanner.setAdapter(adapter);//将起始位置设置在中间，让用户看不到边界vpBanner.setCurrentItem(Integer.MAX_VALUE / 2);//开始轮播handler.sendEmptyMessageDelayed(BANNER_NEXT, 5000);

用户滑动时停止轮播,松开时继续轮播

使用ViewPager的滑动监听事件，判断用户是否正在滑动

        vpBanner.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {@Overridepublic void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}@Overridepublic void onPageSelected(int position) {}@Overridepublic void onPageScrollStateChanged(int state) {switch (state) {case ViewPager.SCROLL_STATE_DRAGGING://用户正在滑动，暂停轮播handler.sendEmptyMessage(BANNER_PAUSE);break;case ViewPager.SCROLL_STATE_IDLE://滑动结束，继续轮播handler.sendEmptyMessageDelayed(BANNER_NEXT, 5000);break;}}});