笔记--viewpager实现广告轮播

来源：互联网发布：windows 最小化消息编辑：程序博客网时间：2024/06/16 07:19

效果图：
这里写图片描述

public class HomeFragment extends Fragment implements ViewPager.OnPageChangeListener {    private static final String TAG = "HomeFragment";    private static final int AUTO_BANNER = 1;    private static final int CANCEL_AUTO_BANNER = -1;    private static final int DOT_DIA = 20;    private static final int DOT_MARGIN = 20;    private static final int DELAY = 3000;    private static final int CYCLE = 3000;    private ViewPager mHomeBanner;    private RecyclerView mHomeRecView;    private BannerPagerAdapter mBanAdapter;    private List<BannerItem> mBannerItems;    private Timer mTimer;    private LinearLayout mDotLayout;    private int mSizeOfImages;    private int mProPosition = 0;    private List<Teacher> mTopTenTeachers;    private TeacherAdapter mTecAdapter;    private ScrollView mScrollView;    public static HomeFragment newInstance() {        return new HomeFragment();    }    private Handler mHandler = new Handler() {        @Override        public void handleMessage(Message msg) {            switch (msg.what) {                case AUTO_BANNER:                    mHomeBanner.setCurrentItem(mHomeBanner.getCurrentItem() + 1);                    break;                case CANCEL_AUTO_BANNER:                    if (mTimer != null) {                        mTimer.cancel();                    }                    mTimer = null;                    break;                default:                    break;            }        }    };    @Override    public void onCreate(@Nullable Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        mTimer = new Timer();        mTopTenTeachers = DataLab.getInstance().getTopTenTeachers();        mBannerItems = DataLab.getInstance().getBannerItems();        mBanAdapter = new BannerPagerAdapter(getActivity(), mBannerItems);        mSizeOfImages = DataLab.getInstance().getBannerItems().size();        mTecAdapter = new TeacherAdapter(getActivity(), mTopTenTeachers);    }    @Nullable    @Override    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,                             @Nullable Bundle savedInstanceState) {        View view = inflater.inflate(R.layout.fragment_home, container, false);        mapComponents(view);        initDots();        mHomeBanner.setAdapter(mBanAdapter);        mHomeBanner.addOnPageChangeListener(this);        mDotLayout.getChildAt(0).setEnabled(true);        startAutoBanner();        mHomeRecView.setLayoutManager(new LinearLayoutManager(getActivity()));        mHomeRecView.setAdapter(mTecAdapter);        return view;    }    @Override    public void onResume() {        super.onResume();        mScrollView.smoothScrollBy(0, 0);//scrollView默认滚动到底部，所以加上此句让其滚动到顶部。    }    private void initDots() {        for (int i = 0; i < mSizeOfImages; i++) {            View dot = new View(getActivity());            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(DOT_DIA, DOT_DIA);            params.leftMargin = DOT_MARGIN;            params.rightMargin = DOT_MARGIN;            dot.setLayoutParams(params);            dot.setBackgroundResource(R.drawable.dot_state);            dot.setEnabled(false);            mDotLayout.addView(dot);        }    }    private void startAutoBanner() {        if (mTimer == null) {            mTimer = new Timer();        }        mTimer.schedule(new TimerTask() {            @Override            public void run() {                mHandler.sendEmptyMessage(AUTO_BANNER);            }        }, DELAY, CYCLE);    }    private void mapComponents(View view) {        mScrollView = (ScrollView) view.findViewById(R.id.scroll_view);        mHomeBanner = (ViewPager) view.findViewById(R.id.home_banner);        mHomeRecView = (RecyclerView) view.findViewById(R.id.home_recycler_view);        mDotLayout = (LinearLayout) view.findViewById(R.id.dot_layout);    }    @Override    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {        //nothing to do.    }    @Override    public void onPageSelected(int position) {        mDotLayout.getChildAt(mProPosition % mSizeOfImages).setEnabled(false);        mDotLayout.getChildAt(position % mSizeOfImages).setEnabled(true);        mProPosition = position;    }    @Override    public void onPageScrollStateChanged(int state) {        if (state == ViewPager.SCROLL_STATE_DRAGGING) {//如果用户自己滑动，则暂时取消自动轮播。            mHandler.sendEmptyMessage(CANCEL_AUTO_BANNER);        } else if (state == ViewPager.SCROLL_STATE_IDLE) {            if (mTimer == null) {                startAutoBanner();            }        }    }}

public class BannerPagerAdapter extends PagerAdapter {    private static final String TAG = "BannerPagerAdapter";    private Context mContext;    private List<BannerItem> mBannerItems;    private List<ImageView> mImageViews = new ArrayList<>();    public BannerPagerAdapter(Context context, List<BannerItem> bannerItems) {        mContext = context;        if (bannerItems == null || bannerItems.isEmpty()) {            mBannerItems = new ArrayList<>();        } else {            mBannerItems = bannerItems;        }        for (int i = 0; i < mBannerItems.size(); i++) {            ImageView imageView = new ImageView(mContext);            imageView.setImageResource(mBannerItems.get(i).getImageId());            mImageViews.add(imageView);        }    }    @Override    public void destroyItem(ViewGroup container, int position, Object object) {        //我们在instantiateItem()方法中已经处理了remove的逻辑，因此这就不需要再次执行了。        //实际上，实验表明这里如果加上了remove的调用，则会出现ViewPager的内容为空的情况。    }    @Override    public Object instantiateItem(ViewGroup container, int position) {        if (position < 0) {//左滑的时候，position可能为负值。            position = mImageViews.size() + position;        }        ImageView imageView = mImageViews.get(position % mImageViews.size());        ViewGroup parent = (ViewGroup) imageView.getParent();        if (parent != null) {//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。            parent.removeView(imageView);        }        final String clickLink = mBannerItems.get(position % mImageViews.size()).getClickLink();        imageView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {//实现点击后，跳转到指定界面的功能，待实现。                Log.d(TAG, clickLink);                ToastUtil.showToastHint(clickLink);            }        });        container.addView(imageView);        return imageView;    }    @Override    public int getCount() {//之所以写一个很大的值，是为了能够循环显示。        return Integer.MAX_VALUE;    }    @Override    public boolean isViewFromObject(View view, Object object) {        return view == object;    }}

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