efunboxReader-android/app/src/main/java/com/edufound/reader/presenter/MyFollowPresenter.java

package com.edufound.reader.presenter;

import android.content.Intent;
import android.graphics.Rect;
import android.view.View;
import android.widget.Toast;

import com.edufound.reader.activity.OthersRecordActivity;
import com.edufound.reader.adapter.MyFollowItemAdapter;
import com.edufound.reader.base.BasePresenter;
import com.edufound.reader.contract.MyFollowContract;
import com.edufound.reader.listener.RecyclerItemClickListener;
import com.edufound.reader.util.SizeUtils;
import com.orhanobut.logger.Logger;

import java.util.ArrayList;
import java.util.List;

import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import io.reactivex.rxjava3.annotations.NonNull;

public class MyFollowPresenter extends BasePresenter<MyFollowContract.View> implements MyFollowContract.Presenter {
    List<Object> mDataList;
    MyFollowItemAdapter myFollowItemAdapter;

    public MyFollowPresenter() {
        mDataList = new ArrayList<>();
        for (int i = 0; i < 30; i++) {
            mDataList.add("i=" + i);
        }
    }

    @Override
    public void initRecyclerView(RecyclerView rv) {
//
        myFollowItemAdapter = new MyFollowItemAdapter(mView.getActivity(), mDataList);
        GridLayoutManager gridLayoutManager = new GridLayoutManager(mView.getActivity(), 3);
        gridLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                return (myFollowItemAdapter.isHeaderView(position) || myFollowItemAdapter.isBottomView(position)) ? gridLayoutManager.getSpanCount() : 1;
            }
        });
        rv.addItemDecoration(new MyFollowItemDecoration(
                SizeUtils.dp2px(mView.getActivity(), 27f),
                SizeUtils.dp2px(mView.getActivity(), 27f)));
        rv.setLayoutManager(gridLayoutManager);
        rv.addOnChildAttachStateChangeListener(new RecyclerView.OnChildAttachStateChangeListener() {
            @Override
            public void onChildViewAttachedToWindow(@androidx.annotation.NonNull View view) {
                addMoreData(rv);
            }

            @Override
            public void onChildViewDetachedFromWindow(@androidx.annotation.NonNull View view) {

            }
        });
        myFollowItemAdapter.setOnItemClickListener(new RecyclerItemClickListener() {
            @Override
            public void onClickListener(int position, View view) {
                Toast.makeText(mView.getActivity(), "click:" + position, Toast.LENGTH_SHORT).show();
                Intent intent = new Intent(mView.getActivity(), OthersRecordActivity.class);
                intent.putExtra("userId", position);
                mView.getActivity().startActivity(intent);
            }
        });
        rv.setAdapter(myFollowItemAdapter);
    }

    public void addMoreData(RecyclerView rv) {
        //获取当前显示的View 的数据
        int childCount = rv.getChildCount();
        //获取最后一具 Item 对应的View
        View childAt = rv.getChildAt(childCount - 1);
        //获取当前军舰中显示的最后一个 Item 的位置  Postion
        int childLayoutPosition = rv.getChildLayoutPosition(childAt);
        //如果不是最后一个就向下滑动

        if (childLayoutPosition < rv.getAdapter().getItemCount() - 2) {
        } else {
            Logger.e("倒数第二个，添加数据");
            mDataList.addAll(mDataList);
            myFollowItemAdapter.addMored(mDataList);
            rv.post(new Runnable() {
                @Override
                public void run() {
                    myFollowItemAdapter.notifyDataSetChanged();
                }
            });
        }
    }
}

class MyFollowItemDecoration extends RecyclerView.ItemDecoration {

    private int mRowSpacing;//行间距
    private int mColumnSpacing;// 列间距

    /**
     * @param rowSpacing    行间距
     * @param columnSpacing 列间距
     */
    public MyFollowItemDecoration(int rowSpacing, int columnSpacing) {
        this.mRowSpacing = rowSpacing;
        this.mColumnSpacing = columnSpacing;
    }

    @Override
    public void getItemOffsets(@NonNull Rect outRect, @NonNull View view, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
        int position = parent.getChildAdapterPosition(view);
        outRect.bottom = mRowSpacing;
        outRect.right = mColumnSpacing;
        if (position < 3) {
            outRect.left = mColumnSpacing;
        }
    }
}