Android studio RecyclerView实现炫酷吸顶效果

这个例子是我看到一篇博客写的，自己在写的过程中发现代码没有给全，于是自己摸索了把代码补全，实现了炫酷的效果并且上传了代码如个有需要的同学请自取，看代码

首先主布局里面一个recyclerview

MinaActivity中逻辑代码

RecyclerView recyclerView;
WaitMVBean waitMVBean;
List list;
List beanList;
/**
 * 联网请求所需的url
 */
public String url="http://api.meituan.com/mmdb/movie/v2/list/rt/order/coming.json?ci=1&limit=12&token=&__vhost=api.maoyan.com&utm_campaign=AmovieBmovieCD-1&movieBundleVersion=6801&utm_source=xiaomi&utm_medium=android&utm_term=6.8.0&utm_content=868030022327462&net=255&dModel=MI%205&uuid=0894DE03C76F6045D55977B6D4E32B7F3C6AAB02F9CEA042987B380EC5687C43&lat=40.100673&lng=116.378619&__skck=6a375bce8c66a0dc293860dfa83833ef&__skts=1463704714271&__skua=7e01cf8dd30a179800a7a93979b430b2&__skno=1a0b4a9b-44ec-42fc-b110-ead68bcc2824&__skcy=sXcDKbGi20CGXQPPZvhCU3%2FkzdE%3D";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(activity_main);
    intoView();
    getDataFromNet();
}

/**
 * 初始化视图
 */
private void intoView(){
    recyclerView= (RecyclerView) findViewById(R.id.recyclerview);
    GridLayoutManager gridLayoutManager=new GridLayoutManager(this,1);
    recyclerView.setLayoutManager(gridLayoutManager);

}

private void setPullAction(List list){
    beanList=new ArrayList<>();
    for (int i=0;i;i++){
        NameBean nameBean=new NameBean();
        String name=list.get(i).getComingTitle();
        nameBean.setName(name);
        beanList.add(nameBean);
    }
}

/**
 * 请求数据
 */
private void getDataFromNet(){
    RequestQueue requestQueue= Volley.newRequestQueue(this);

    StringRequest stringRequest=new StringRequest(com.android.volley.Request.Method.GET, url, new com.android.volley.Response.Listener() {
        @Override
        public void onResponse(String s) {
            Log.e("数据",s);
            processData(s);

        }
    }, new com.android.volley.Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError volleyError) {
        Toast.makeText(MainActivity.this,"请求失败",Toast.LENGTH_LONG).show();
        }
    });
    requestQueue.add(stringRequest);
}

/**
 * 解析数据
 * @param s
 */
private void processData(String s){
    final Gson gson=new Gson();
    waitMVBean=gson.fromJson(s,WaitMVBean.class);
    list=waitMVBean.getData().getComing();
    setPullAction(list);

    recyclerView.addItemDecoration(new SectionDecoration(beanList, this, new SectionDecoration.DecorationCallback() {
        @Override
        public String getGroupId(int position) {
            if (beanList.get(position).getName()!=null){
                return beanList.get(position).getName();
            }
            return "-1";
        }

        //获取同一组的内容
        @Override
        public String getGroupFirstLine(int position) {
            if (beanList.get(position).getName()!=null){
                return beanList.get(position).getName();
            }
            return "";
        }
    }));
    MyRecyclerAdapter myRecyclerAdapter=new MyRecyclerAdapter(MainActivity.this,list);
    recyclerView.setAdapter(myRecyclerAdapter);
}

适配器代码

ublic class MyRecyclerAdapter extends RecyclerView.Adapter {
    private final List list;
    private final Context context;
    private final LayoutInflater inflater;

    public MyRecyclerAdapter(Context context, List list) {
        this.context = context;
        this.list = list;
        inflater = LayoutInflater.from(context);

    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        return new MyViewHolder(inflater.inflate(R.layout.data_item,null));
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
              MyViewHolder holder1= (MyViewHolder) holder;
                holder1.setDate(position);
    }

    @Override
    public int getItemCount() {
        return list.size();
    }

    class MyViewHolder extends RecyclerView.ViewHolder {
        ImageView image;
        TextView mvName;
        TextView tvPeople;
        TextView tvProfessional;
        TextView mvDec;
        TextView mvDate;

        public MyViewHolder(View itemView) {
            super(itemView);
            image = (ImageView) itemView.findViewById(R.id.image);
            mvName = (TextView) itemView.findViewById(R.id.mv_name);
            tvPeople = (TextView) itemView.findViewById(R.id.tv_people);
            tvProfessional = (TextView) itemView.findViewById(R.id.tv_professional);
            mvDec = (TextView) itemView.findViewById(R.id.mv_dec);
            mvDate = (TextView) itemView.findViewById(R.id.mv_date);
        }

        public void setDate(int position){
            WaitMVBean.DataBean.ComingBean comingBean=list.get(position);
            mvName.setText(comingBean.getNm());
            mvDate.setText(comingBean.getShowInfo());
            mvDec.setText(comingBean.getScm());
            String url=comingBean.getImg();
            String imageurl=url.replaceAll("w.h","50.80");//字符串替换
            Log.e("图片路径",url);
            Glide.with(context).load(imageurl).into(image);
        }


    }

布局懒得写的小朋友直接贴上

xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    android:background="#ffffff"
    android:gravity="center_vertical"
    android:layout_height="match_parent"

    >
            android:id="@+id/image"
        android:layout_width="70dp"
        android:layout_height="110dp"
        android:layout_marginBottom="5dp"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="8dp"
        android:layout_marginTop="5dp" />

            android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginLeft="6dp"
        android:layout_weight="1"
        android:orientation="vertical">

                    android:id="@+id/mv_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="神奇動物在哪裏"
            android:textColor="#000000"
            android:textSize="15sp" />

                    android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

                            android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="观众"
                android:textColor="#55000000"
                android:textSize="14sp" />

                            android:id="@+id/tv_people"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="9.0 "
                android:textColor="#FFCE42"
                android:textSize="18sp" />

                            android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text=" | 专业"
                android:textColor="#55000000"
                android:textSize="14sp" />

                            android:id="@+id/tv_professional"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="6.7"
                android:textColor="#FFCE42"
                android:textSize="18sp" />
        

                    android:id="@+id/mv_dec"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="8dp"
            android:text="神奇動物城，法師顯超能"
            android:textColor="#99000000"
            android:textSize="11sp" />

                    android:id="@+id/mv_date"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:text="今天165家影院放映2088场"
            android:textColor="#99000000"
            android:textSize="11sp" />

        

下面这个就是写悬浮栏的逻辑代码了

public class SectionDecoration extends RecyclerView.ItemDecoration {
    private List beanList;
    private TextPaint textPaint;
    private Paint paint;
    private int topGap;
    private int alignBottom;
    private DecorationCallback callback;
    private Paint.FontMetrics fontMetrics;

    interface DecorationCallback{
        String getGroupId(int position);
        String getGroupFirstLine(int position);
    }
    private boolean isFirstInGroup(int pos){
        if (pos==0){
            return  true;
        }else {
             //因为是根据字符串的内容的相同与否来判断是不是同意组的，所以此处的标记id要是String类型
            //如果只做联系人列表悬浮框里面显示的是字母则标记id直接用int类型就行了
            String prevGroupId=callback.getGroupId(pos-1);
            String groupId=callback.getGroupId(pos);
            //判断前一个字符串与当前字符串是否相同
            if(prevGroupId.equals(groupId)){
                return false;
            }else {
                return true;
            }
        }

    }
    public SectionDecoration(List beanList, Context context,DecorationCallback callback ){
        Resources resources=context.getResources();
        this.beanList=beanList;
        this.callback=callback;
        //设置悬浮栏的画笔
        paint=new Paint();
        paint.setColor(ContextCompat.getColor(context,R.color.colorPrimary));
        //设置悬浮栏中文本的画笔
        textPaint=new TextPaint();
        textPaint.setAntiAlias(true);
        textPaint.setTextSize(DensityUtil.dip2px(context,12));
        textPaint.setTextAlign(Paint.Align.LEFT);
        textPaint.setColor(Color.WHITE);
        fontMetrics=new Paint.FontMetrics();
        //决定悬浮栏的高度等
        topGap=resources.getDimensionPixelSize(R.dimen.sectioned_top);
        //决定文本的显示位置等
        alignBottom=resources.getDimensionPixelSize(R.dimen.sectioned_alignBottom);
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        int pos=parent.getChildAdapterPosition(view);
        String groupId=callback.getGroupId(pos);
        if (groupId.equals("-1"))return;
        //只有是同一组的第一个才显示悬浮栏
        if(pos==0 || isFirstInGroup(pos)){
            outRect.top=topGap;
            if (beanList.get(pos).getName()==""){
                outRect.top=0;
            }
        }else {
            outRect.top=0;
        }
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        super.onDraw(c, parent, state);
        int left=parent.getPaddingLeft();
        int right=parent.getWidth()-parent.getPaddingRight();
        int childCount=parent.getChildCount();
        for (int i=0;i;i++){
            View view=parent.getChildAt(i);
            int position=parent.getChildAdapterPosition(view);
            String groupId=callback.getGroupId(position);
            if (groupId.equals("-1"))return;
            String textLine=callback.getGroupFirstLine(position).toUpperCase();
            if (textLine==""){
                float top=view.getTop();
                float bottom=view.getTop();
                c.drawRect(left,top,right,bottom,paint);
                return;
            }else {
                if (position==0|| isFirstInGroup(position)){
                    float top=view.getTop()-topGap;
                    float bottom=view.getTop();
                    //绘制悬浮栏
                    c.drawRect(left,top-topGap,right,bottom,paint);
                    //绘制文本
                    c.drawText(textLine,left,bottom,textPaint);
                }

            }
        }
    }

    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        super.onDrawOver(c, parent, state);
        int itemCount=state.getItemCount();
        int childCount=parent.getChildCount();
        int left=parent.getPaddingLeft();
        int right=parent.getWidth()-parent.getPaddingRight();
        String preGroupId="";
        String groupId="-1";
        for (int i=0; i;i++){
            View view=parent.getChildAt(i);
            int position=parent.getChildAdapterPosition(view);
            preGroupId=groupId;
            groupId=callback.getGroupId(position);
            if (groupId.equals("-1") || groupId.equals(preGroupId))continue;
            String textLine=callback.getGroupFirstLine(position).toUpperCase();
            if (TextUtils.isEmpty(textLine))continue;
            int viewBottom=view.getBottom();
            float textY=Math.max(topGap,view.getTop());
            //下一个和当前不一样移动当前
            if (position+1callback.getGroupId(position+1);
                //组内最后一个view进入了header
                if (nextGroupId!=groupId&&viewBottom;
                }
            }
            //textY-toGap决定了悬浮栏绘制的高度和位置
            c.drawRect(left,textY-topGap,right,textY,paint);
            //left+2*alignbottom决定了文本往右偏移的多少
            c.drawText(textLine,left+2*alignBottom,textY-alignBottom,textPaint);

        }
    }


}

NameBean实体类

public class NameBean {
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    String name;
}

WaitMVBean 这个可以根据返回的json数据设计使用GsonFrom工具

DensityUtil工具类

public class DensityUtil {
    public static int dip2px(Context context,float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }


    public static int px2dip(Context context,float pxValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (pxValue / scale + 0.5f);
    }
}