Android RecyclerView +SnapHelper 实现横向滚动自动滚动到中心控件并选中

2019年6月21日 674次阅读来源: 小于先森

效果图

《Android RecyclerView +SnapHelper 实现横向滚动自动滚动到中心控件并选中》

此效果已被产品砍掉，所以有些适配bug就不修改了此博客只为记录下代码
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代码

布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:padding="15dp" android:layout_width="85dip" android:layout_height="wrap_content" android:gravity="center" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:background="@drawable/bg_circle_5_blue" >
    <de.hdodenhof.circleimageview.CircleImageView  android:id="@+id/img_face" android:layout_width="55dip" android:layout_height="55dip" android:src="@drawable/default_img" />
    <TextView  android:id="@+id/tv_name" android:layout_width="wrap_content" android:layout_height="wrap_content" android:singleLine="true" android:layout_marginTop="10dp" android:textSize="@dimen/px_28" android:text="@string/default_string" />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
    <corners  android:radius="5dp" ></corners>
    <stroke  android:width="1dp" android:color="@color/most_line" ></stroke>
    <solid  android:color="@color/white" ></solid>
</shape>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
    <corners  android:radius="5dp" ></corners>
    <stroke  android:width="1dp" android:color="@color/most_line" ></stroke>
    <solid  android:color="@color/app_color_theme" ></solid>
</shape>

Adapter

package inter.baisong.adapter;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.uuzuche.lib_zxing.DisplayUtil;

import inter.baisong.R;
import inter.baisong.base.ConfigYibaisong;

/** * Created by 于德海 on 2018/6/1. * package inter.baisong.adapter * email : yudehai0204@163.com * * @describe */

public class UnionUnionAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    private Context mContext;
    private final int PLACEHOLDER_CODE =-1;
    private int placeholder_width;//布局写死85dip +20 dip margin
    private int center_index,last_index;
    public UnionUnionAdapter(Context mContext) {
        this.mContext = mContext;
        placeholder_width = DisplayUtil.dip2px(mContext,105);
        center_index=1;
        last_index=1;
    }

    /*** * 正常一屏显示的个数 * @return */
    public int getMeaSureItemCount(){
        if(ConfigYibaisong.window_x%placeholder_width>0){
            return ConfigYibaisong.window_x/placeholder_width+1;
        }else {
            return ConfigYibaisong.window_x/placeholder_width+1;
        }
    }
    /*** * 设置中心 * @param index */
    public void setCenter_index(int index){
        if(index==center_index)
            return;
        last_index = center_index;
        center_index = index;
        notifyItemChanged(last_index);
        notifyItemChanged(center_index);
    }


    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if(viewType==PLACEHOLDER_CODE){
            View view = new View(mContext);
            int view_width = parent.getMeasuredWidth()/2-placeholder_width/2;
            RecyclerView.LayoutParams params = new RecyclerView.LayoutParams(view_width,RecyclerView.LayoutParams.WRAP_CONTENT);
            view.setLayoutParams(params);
            PlaceHolderViewHolder holder = new PlaceHolderViewHolder(view);
            return holder;
        }
        View view = LayoutInflater.from(mContext).inflate(R.layout.item_frag_union_union,parent,false);
        UnionViewHolder viewHolder = new UnionViewHolder(view);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if(holder instanceof UnionViewHolder){
            if(position == center_index){
                holder.itemView.setBackgroundResource(R.drawable.bg_union_item_center);
            }else {
                holder.itemView.setBackgroundResource(R.drawable.bg_union_item_default);
            }
        }
    }

    @Override
    public int getItemCount() {
        return 20+2;
    }

    @Override
    public int getItemViewType(int position) {
        if(position==0||position== getItemCount()-1){
            return PLACEHOLDER_CODE;
        }
        return super.getItemViewType(position);
    }

    class UnionViewHolder extends RecyclerView.ViewHolder{

        public UnionViewHolder(View itemView) {
            super(itemView);
        }
    }

    class PlaceHolderViewHolder extends RecyclerView.ViewHolder{

        public PlaceHolderViewHolder(View itemView) {
            super(itemView);
        }
    }

}

Fragment

package inter.baisong.fragment;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.LinearSnapHelper;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;

import com.lzy.okgo.utils.OkLogger;

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

import inter.baisong.R;
import inter.baisong.adapter.HomeViewPagerAdapter;
import inter.baisong.adapter.UnionExperienceAdapter;
import inter.baisong.adapter.UnionRedPacketAdapter;
import inter.baisong.adapter.UnionUnionAdapter;
import inter.baisong.bean.BannerBean;
import inter.baisong.widgets.CoustomSwipRefresh;

/** * Created by 于德海 on 2018/5/31. * package inter.baisong.fragment * email : yudehai0204@163.com * * @describe */

public class UnionFragment extends Fragment {
    private View view;
    private CoustomSwipRefresh mSwipe;
    private RecyclerView mRecyclerView,mRecyclerView_redpecket,mRecyclerView_experience;
    private ViewPager mViewPager;
    private UnionUnionAdapter mUinonAdapter;
    private HomeViewPagerAdapter mBannerAdapter;
    private LinearLayout ll_hotsale,ll_tower;
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        if(view==null){
            view = inflater.inflate(R.layout.frag_union,container,false);
            mSwipe = view.findViewById(R.id.mSwipe);
            mViewPager = view.findViewById(R.id.mViewPager);
            mRecyclerView = view.findViewById(R.id.mRecyclerView);
            mRecyclerView_redpecket = view.findViewById(R.id.mRecyclerView_redpecket);
            mRecyclerView_experience = view.findViewById(R.id.mRecyclerView_experience);
            ll_hotsale = view.findViewById(R.id.ll_hotsale);
            ll_tower = view.findViewById(R.id.ll_tower);
            mUinonAdapter = new UnionUnionAdapter(getActivity());
            mBannerAdapter = new HomeViewPagerAdapter(getActivity());

        }
        initData();
        initListener();
        return view;
    }

    private void initData() {
        /*** * 假数据 banner */
        mViewPager.setAdapter(mBannerAdapter);
        List<BannerBean.Data> banner_list =new ArrayList<>();
        for (int i=0;i<3;i++){
            BannerBean.Data data = new BannerBean().new Data();
            if(i==0){
                data.setPicpatch("https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=2407350602,1649604847&fm=27&gp=0.jpg");
            }
            if(i==1){
                data.setPicpatch("https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=204321001,3815511924&fm=27&gp=0.jpg");
            }
            if(i==2){
                data.setPicpatch("https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=3821526675,3796993096&fm=27&gp=0.jpg");
            }
            banner_list.add(data);
        }
        mBannerAdapter.setmList(banner_list);
        mBannerAdapter.notifyDataSetChanged();
        //公会RecyclerView
        mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity(),LinearLayoutManager.HORIZONTAL,false));
        LinearSnapHelper mLinearSnapHelper = new LinearSnapHelper();
        mLinearSnapHelper.attachToRecyclerView(mRecyclerView);
        mRecyclerView.setAdapter(mUinonAdapter);
        //红包
        mRecyclerView_redpecket.setLayoutManager(new LinearLayoutManager(getActivity(),LinearLayoutManager.HORIZONTAL,false));
        mRecyclerView_redpecket.setAdapter(new UnionRedPacketAdapter(getActivity()));
        //体验
        mRecyclerView_experience.setLayoutManager(new LinearLayoutManager(getActivity(),LinearLayoutManager.HORIZONTAL,false));
        mRecyclerView_experience.setAdapter(new UnionExperienceAdapter(getActivity()));
        //热卖
        ll_hotsale.removeAllViews();
        for (int i=0;i<3;i++){
            View view = LayoutInflater.from(getActivity()).inflate(R.layout.item_frag_union_hotsale,ll_hotsale,false);
            ll_hotsale.addView(view);
        }
        //任务
        ll_tower.removeAllViews();
        for (int i=0;i<3;i++){
            View view = LayoutInflater.from(getActivity()).inflate(R.layout.item_frag_union_tower,ll_tower,false);
            ll_tower.addView(view);
        }
    }
    private void initListener() {

        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            int itemCount_page = mUinonAdapter.getMeaSureItemCount();
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                if(newState==RecyclerView.SCROLL_STATE_IDLE){
                    RecyclerView.LayoutManager manager = mRecyclerView.getLayoutManager();
                    if(manager instanceof LinearLayoutManager){
                        LinearLayoutManager linearManager = (LinearLayoutManager) manager;
                        //获取最后一个可见view的位置
                        int lastItemPosition = linearManager.findLastVisibleItemPosition();
                        //获取第一个可见view的位置
                        int firstItemPosition = linearManager.findFirstVisibleItemPosition();
                        if(lastItemPosition-firstItemPosition<itemCount_page){
                            if(firstItemPosition==0){
                                mUinonAdapter.setCenter_index(1);
                            }else {
                                mUinonAdapter.setCenter_index(mUinonAdapter.getItemCount()-2);
                            }
                        }else {
                            mUinonAdapter.setCenter_index(firstItemPosition+itemCount_page/2);
                        }
                        OkLogger.e("union",firstItemPosition+" ====== "+lastItemPosition+" ==== "+itemCount_page);
                    }
                }
            }
        });
    }
}

尾语

UI效果永远最后写要不极有可能等于白费功夫。。。

2018.6.1

    原文作者：小于先森
    原文地址: https://blog.csdn.net/a940659387/article/details/80540338
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。