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

效果图

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 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-firstItemPositionif(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

效果图

代码

尾语

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