viewpager嵌套gridview实现美团左右滑动查看更多分类的功能

    ![Screenshot_2019-02-21-19-09-59-69.png](https://upload-images.jianshu.io/upload_images/11970412-2a2ce831f7bc437d.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

界面很简陋，没有找相应的图，主要是记录使用方法，便于以后查询

1、MainActivity

public class MainActivity extends AppCompatActivity {
    // nox_adb.exe connect 127.0.0.1:62001
    ArrayList<GridItem> mList;
    MyViewPagerAdapter mViewPagerAdapter;
    ViewPager mViewPager;
    int mTotalPage; //总的页数
    int mPageSize = 10; //每页显示的最大的数量
    List<View> mViewPagerList;//GridView作为一个View对象添加到ViewPager集合中
    int[] imageId;// 图片id的集合
    CircleIndicator indicator;// 指示器

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        initData();
    }

    private void initView() {
        mViewPager = (ViewPager) findViewById(R.id.viewPager);
        indicator = (CircleIndicator) findViewById(R.id.indicator);
        mList = new ArrayList<>();
        imageId = new int[]{
                R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round,
                R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round,
                R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round,
                R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round,
                R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round,
                R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round, R.mipmap.ic_launcher_round,
        };
        for (int i = 0; i < imageId.length; i++) {
            mList.add(new GridItem(imageId[i]));
        }
    }

    private void initData() {
        //总的页数=总数/每页数量，并向上取整取整
        mTotalPage = (int) Math.ceil(mList.size() * 1.0 / mPageSize);
        mViewPagerList = new ArrayList<>();
        for (int i = 0; i < mTotalPage; i++) {
            final GridView gridView = (GridView) View.inflate(this, R.layout.grid_item, null);
            gridView.setAdapter(new GridViewAdapter(this, mList, i, mPageSize));
            //每一个GridView作为一个View对象添加到ViewPager集合中
            mViewPagerList.add(gridView);
        }
        mViewPagerAdapter = new MyViewPagerAdapter(this, mViewPagerList);
        mViewPager.setAdapter(mViewPagerAdapter);
        indicator.setViewPager(mViewPager);
    }

2、MyViewPagerAdapter

public class MyViewPagerAdapter extends PagerAdapter {

    List<View> mViewList;//View就是GridView所显示的内容
    Context mContext;

    public MyViewPagerAdapter(Context context, List<View> viewList) {
        this.mContext = context;
        this.mViewList = viewList;
    }

    @Override
    public int getCount() {
        if (mViewList != null && mViewList.size() > 0) {
            return mViewList.size();
        }
        return 0;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == object;
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        container.addView(mViewList.get(position));
        return mViewList.get(position);
    }

    /**
     * 将当前的View添加到ViewGroup容器中
     * 这个方法，return一个对象，这个对象表明了PagerAdapter适配器选择哪个对象放在当前的ViewPage上
     */
    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((View) object);
    }
}

3、GridViewAdapter

public class GridViewAdapter extends BaseAdapter {
    private static final String TAG = "GridViewAdapter";
    Context mContext;
    ArrayList<GridItem> mList = new ArrayList<>();
    int mIndex; // 页数下标，标示第几页，从0开始
    int mPargerSize;// 每页显示的最大的数量
    DisplayMetrics metrics;

    public GridViewAdapter(Context context, ArrayList<GridItem> list, int mIndex, int mPagerSize) {
        this.mContext = context;
        this.mList = list;
        this.mIndex = mIndex;
        this.mPargerSize = mPagerSize;

    }

    @Override
    public int getCount() {
        return mList.size() > (mIndex + 1) * mPargerSize ?
                mPargerSize : (mList.size() - mIndex * mPargerSize);
    }

    @Override
    public Object getItem(int position) {
        return mList.get(position + mIndex * mPargerSize);
    }

    @Override
    public long getItemId(int position) {
        return position + mIndex * mPargerSize;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup viewGroup) {
        GridViewHolder holder;
        metrics = mContext.getResources().getDisplayMetrics();
        int widthPixels = metrics.widthPixels;
        int width = widthPixels / 5;

        int height = Dp2Px(mContext, 80);
        if (convertView == null) {
            holder = new GridViewHolder();
            convertView = View.inflate(mContext, R.layout.gridview_item, null);
            holder.ivItemImage = convertView.findViewById(R.id.ivMenu);
            AbsListView.LayoutParams params = (AbsListView.LayoutParams) convertView.getLayoutParams();
            convertView.setTag(holder);
            if (params == null) {
                params = new AbsListView.LayoutParams(width, height);
                convertView.setLayoutParams(params);
            } else {
                params.width = width;
                params.height = height;
            }
        } else {
            holder = (GridViewHolder) convertView.getTag();
        }

        //重新确定position因为拿到的总是数据源，数据源是分页加载到每页的GridView上的
        final int pos = position + mIndex * mPargerSize;//假设mPageSiez
        //假设mPagerSize=8，假如点击的是第二页（即mIndex=1）上的第二个位置item(position=1),那么这个item的实际位置就是pos=9
        holder.ivItemImage.setImageResource(mList.get(pos).getImageId());
//        holder.layout.setOnClickListener(new View.OnClickListener() {
//            @Override
//            public void onClick(View v) {
//                if (pos == 7 && mList.get(pos).getImageText().equals(mContext.getString(R.string.ad))) {
////                    mHandler.sendEmptyMessageAtTime(0, 1000);
//                } else {
////                    Intent intent = new Intent();
////                    intent.setClass(mContext, DetailsActivity.class);
////                    intent.putExtra("Title", mList.get(pos).getImageText());
////                    mContext.startActivity(intent);
//                }
//            }
//        });
        return convertView;
    }

    static class GridViewHolder {
        ImageView ivItemImage;
    }

// dp转px
    public static int Dp2Px(Context context, float dp) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dp * scale + 0.5f);
    }
}

4、activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.qqq.photogridview.MainActivity">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="180dp"
        android:background="#FFFFFF">

        <android.support.v4.view.ViewPager
            android:id="@+id/viewPager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <me.relex.circleindicator.CircleIndicator
            android:id="@+id/indicator"
            android:layout_width="match_parent"
            android:layout_height="20dp"
            android:layout_alignParentBottom="true"
            app:ci_drawable="@drawable/black_radius"
            app:ci_drawable_unselected="@drawable/white_radius" />
    </RelativeLayout>
</RelativeLayout>

5、gridview_item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/ivMenu"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:scaleType="fitCenter" />

</RelativeLayout>

6、grid_item.xml

<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fadeScrollbars="true"
    android:numColumns="5">

</GridView>

7、indicator_animator.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="@android:integer/config_shortAnimTime">

    <objectAnimator
        android:propertyName="alpha"
        android:valueFrom="0.1"
        android:valueTo="1.0"
        android:valueType="floatType" />

    <objectAnimator
        android:propertyName="rotation"      //旋转
        android:valueFrom="0"
        android:valueTo="180"
        android:valueType="floatType" />
    <objectAnimator
        android:propertyName="translationY"
        android:valueFrom="0"
        android:valueTo="-5dp"
        android:valueType="floatType" />
</set>

8、indicator_animator_reverse.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="@android:integer/config_shortAnimTime">

    <objectAnimator
        android:propertyName="alpha"    //     透明度
        android:valueFrom="1.0"
        android:valueTo="0.1"
        android:valueType="floatType" />
    <objectAnimator
        android:propertyName="translationY"  //Y轴移动
        android:valueFrom="-5dp"   // 起点
        android:valueTo="0"   //  终点
        android:valueType="floatType" />    //   移动距离的单位
</set>

9、black_radius_square.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="@android:color/black" />

    <corners android:radius="2dp" />    //矩形四角圆弧角度
</shape>

10、最后是指示器的依赖

implementation 'me.relex:circleindicator:1.2.2'