StaggeredGridLayoutManager实现瀑布流视

1. RecyclerView下StaggeredGridLayoutManager基本使用

recyclerView的简单使用在此不多口舌，先初始化StaggeredGridLayoutManager。

  @Override
    public void InitViewAndData() {
        mRecyclerView = f(R.id.rv_attention);
        mRefreshLayout = f(R.id.vhrf_attention);
        mRecyclerView.setNestedScrollingEnabled(false);
        layoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);
        layoutManager.setGapStrategy(StaggeredGridLayoutManager.GAP_HANDLING_NONE);     //防止瀑布流图片闪烁
        mRecyclerView.setLayoutManager(layoutManager);
        mRecyclerView.setAdapter(mAdapter);
        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                layoutManager.invalidateSpanAssignments();//防止瀑布流图片闪烁
            }
        });
    }

2. 自定义ViewHolder

recyclerView封装了ViewHolder的回收复用机制，只需要按标准流程实现头部广告位的ViewHolder以及分栏Header条等item的ViewHolder。

public class LiveNoticeVH extends RecyclerView.ViewHolder {

    private static final String TAG = "LiveNoticeVH";
    private RecyclerView rv_live_notice;
    private LiveNoticeAdapter mAdapter;
    private TextView tv_header;
    private FrameLayout fl_empty_view;
    private LinearLayout ll_content_view;

    public LiveNoticeVH(View itemView) {
        super(itemView);
        rv_live_notice = ViewUtils.f(itemView, R.id.rv_live_notice);
        tv_header = ViewUtils.f(itemView, R.id.tv_header);
        fl_empty_view = ViewUtils.f(itemView, R.id.fl_empty_view);
        ll_content_view = ViewUtils.f(itemView, R.id.ll_content_view);
        tv_header.setText("关注的直播");
//        rv_live_notice.setLayoutManager(new GridLayoutManager(itemView.getContext(),2));
        rv_live_notice.setLayoutManager(new LinearLayoutManager(itemView.getContext(), LinearLayoutManager.HORIZONTAL, false));
//        rv_live_notice.setNestedScrollingEnabled(false);
        mAdapter = new LiveNoticeAdapter(rv_live_notice);
        rv_live_notice.setAdapter(mAdapter);
        mAdapter.setOnRVItemClickListener(new BGAOnRVItemClickListener() {
            @Override
            public void onRVItemClick(ViewGroup parent, View itemView, int position) {
                try {
                    SubscriptionInfo item = mAdapter.getItem(position);
                    if (ICoreManagerBase.getCore(ILivePluginCore.class) != null) {
                        ICoreManagerBase.getCore(ILivePluginCore.class).getTemplateSelectorInstance().universalToChannel(itemView.getContext(), item.sid, item.ssid, item.liveId, "HomeLiveNoticePush", item.templateId, null);
                    }
                }catch (Exception e){
                    MLog.info(TAG,"ex="+e);
                }
            }
        });
    }

    public void setData(List<SubscriptionInfo> attentionInfoList) {
        MLog.info(TAG, "[initData] debug data=" + attentionInfoList);
//        MLog.error("LiveNoticeVH","setData size="+attentionInfoList.size());
        if (attentionInfoList == null) {
            fl_empty_view.setVisibility(View.VISIBLE);
            ll_content_view.setVisibility(View.GONE);
        } else {
            if (attentionInfoList.size() > 0) {
                fl_empty_view.setVisibility(View.GONE);
                ll_content_view.setVisibility(View.VISIBLE);
//                mAdapter.notifyDataSetChanged();
            } else {
                fl_empty_view.setVisibility(View.VISIBLE);
                ll_content_view.setVisibility(View.GONE);
            }
        }
        mAdapter.setData(attentionInfoList);
        mAdapter.notifyDataSetChanged();
    }
}

3. 构造支持多种item类型的Adapter

从上面的配置我们清楚StaggeredGridLayoutManager显示2列数据，但是Banner位和header条是占据整行的，因此在onCreateViewHolder()里要通过setFullSpan()方式实现单条item占满整行。

public class ShenquAttentionRecyclerAdapter extends RecyclerView.Adapter {
    public static final int VIEW_TYPE_LIVE_NOTICE = R.layout.vh_live_notice;
    public static final int VIEW_TYPE_ATTENTION_VIDEO = R.layout.vh_attention_video;
    public static final int VIEW_TYPE_BASE_HEADER = R.layout.vh_base_header;
    public static final int VIEW_TYPE_EMPTY_ATTENTION_VIDEO=R.layout.vh_empty_attention_video;
    
    @Override
    public void onBindViewHolder(final RecyclerView.ViewHolder holder, final int position) {
        if (holder instanceof LiveNoticeVH) {
            LiveNoticeVH liveNoticeVH = (LiveNoticeVH) holder;
            liveNoticeVH.setData(liveNoticeData);
        } else if (holder instanceof AttentionVideoVH && attentionVideoList.size() > 0) {
            MLog.debug(TAG, "position=" + position);
            AttentionVideoVH attentionVideoVH = (AttentionVideoVH) holder;
            attentionVideoVH.initData(attentionVideoList.get(position - count));
            holder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (mClickListener != null) {
                        mClickListener.onItemClick(position - count, v, holder);
                    }
                }
            });
        }else if(holder instanceof EmptyAttentionVideoVH ){
            View itemView  = holder.itemView;
            RecyclerView.LayoutParams param= (RecyclerView.LayoutParams) itemView.getLayoutParams();
            if (isHideAttentionView){
                param.height = LinearLayout.LayoutParams.WRAP_CONTENT;
                param.width = LinearLayout.LayoutParams.MATCH_PARENT;
                itemView.setVisibility(View.VISIBLE);
            }else{
                itemView.setVisibility(View.GONE);
                param.height = 0;
                param.width = 0;
            }
            itemView.setLayoutParams(param);
        }
    }
    
     @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());     //Inflater为全局单例模式
        View itemView = inflater.inflate(viewType, parent, false);
        StaggeredGridLayoutManager.LayoutParams layoutParams = (StaggeredGridLayoutManager.LayoutParams) itemView.getLayoutParams();
        layoutParams.setFullSpan(true);//将 StaggeredGrid的某个item直接占满宽
        if (viewType == VIEW_TYPE_LIVE_NOTICE) {       //直播预览
            LiveNoticeVH liveNoticeVH = new LiveNoticeVH(itemView);
            return liveNoticeVH;
        } else if (viewType == VIEW_TYPE_BASE_HEADER) {    //标题头
            return new BaseHeaderVH(itemView);
        } else if (viewType == VIEW_TYPE_ATTENTION_VIDEO) {
            AttentionVideoVH attentionVideoVH = new AttentionVideoVH(itemView);
            layoutParams.setFullSpan(false);
            return attentionVideoVH;
        } else return new EmptyAttentionVideoVH(itemView);
    }


    @Override
    public int getItemViewType(int position) {
        if (position == 0) {
            return VIEW_TYPE_LIVE_NOTICE;
        } else if (position == 1) {
            return VIEW_TYPE_BASE_HEADER;
        }else if(position==2){
            return VIEW_TYPE_EMPTY_ATTENTION_VIDEO ;
        }
        else {
            return VIEW_TYPE_ATTENTION_VIDEO;
        }
    }
}