ViewPager的简单优化和实现大图轮播

来源：互联网发布：广州恒大淘宝球员名单编辑：程序博客网时间：2024/06/09 17:51
大图轮播的实现方式就是通过ViewPager实现，然后定时改变ViewPager的setCurrentItem。虽然ViewPager加载几张图片不会导致程序崩溃，但是能优化的地方最好还是优化
代码
public class HomePictureHolder extends BaseHolder<List<String>> {    private ViewPager viewPager;    private List<String> datas;    @Override    protected void refreshView(List<String> datas) {        this.datas = datas;        viewPager.setAdapter(new HomePictureAdapter());        viewPager.setCurrentItem(1000 * datas.size());        viewPager.setOnTouchListener(new View.OnTouchListener() {            @Override            public boolean onTouch(View v, MotionEvent event) {                switch (event.getAction()) {                    case MotionEvent.ACTION_DOWN:                        auToRunTask.stop();                        break;                    // 事件的取消，即在viewpager按下，不在viewpager松开,会导致不在viewpager松开，viewpager不会自动轮播                    case MotionEvent.ACTION_CANCEL:                        auToRunTask.start();                        break;                    case MotionEvent.ACTION_UP:                        auToRunTask.start();                        break;                }                return false;            }        });        auToRunTask = new AuToRunTask();        auToRunTask.start();    }    @Override    protected View initView() {        viewPager = new ViewPager(UiUtils.getContext());        viewPager.setLayoutParams(new AbsListView.LayoutParams(LayoutParams.MATCH_PARENT,                (int) UiUtils.getResource().getDimension(R.dimen.itme_app_height)));        return viewPager;    }    private boolean flag;    private AuToRunTask auToRunTask;    public class AuToRunTask implements Runnable {        @Override        public void run() {            if (flag) {                UiUtils.cancel(this);  // 取消之前                int currentItem = viewPager.getCurrentItem();                viewPager.setCurrentItem(++currentItem);                //  延迟执行当前的任务                UiUtils.postDelayed(this,5000);            }        }        /* 开始自动轮播*/        public void start(){            if(!flag){                UiUtils.cancel(this);                flag = true;                UiUtils.postDelayed(this,5000);            }        }        /* 停止自动轮播*/        public void stop(){            if(flag){                UiUtils.cancel(this);                flag = false;            }        }    }    class HomePictureAdapter extends PagerAdapter {        //把ImagerVIew放到一个公共内存，以复用        LinkedList<ImageView> convertView = new LinkedList<>();        @Override        public int getCount() {            return Integer.MAX_VALUE;        }        @Override        public boolean isViewFromObject(View view, Object object) {            return view == object;        }        @Override        public Object instantiateItem(ViewGroup container, int position) {            int index = position % datas.size();            ImageView view;            if (convertView.size() > 0) {                view = convertView.remove(0);//把ImageView从公共内存中取出            } else {                view = new ImageView(UiUtils.getContext());            }            bitmapUtils.display(view, HttpHelp.SERVER_URL + "image?name=" + datas.get(index));            container.addView(view);            return view;        }        @Override        public void destroyItem(ViewGroup container, int position, Object object) {            ImageView imageView = (ImageView) object;            //viewPager移除View时，把ImagerVIew放到公共内存            convertView.add(imageView);            container.removeView(imageView);        }    }}
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