RecyclerView实现多种效果

本文主要介绍RecyclerView实现多种效果，以聊天界面为例。

原理

• getItemViewType(): 获取每一个item的类型，这里面每一个item的类型是自己定制的，可以有一种，也可以有多种。
• onCreateViewHolder(): 针对不同类型的item来创建不同类型的viewholder从而inflate不同的layout
• onBindViewHolder(): 针对不同类型的viewholder来绑定不同的数据

这个例子处理办法是将数据封装为bean，bean中包含item的type，在创建viewholder绑定数据的时候再判断就可以了。

public class ChatAdapter extends RecyclerView.Adapter {
    private static final String TAG = "ChatAdapter";

    private Context context;
    private LayoutInflater inflater;
    private List items = new ArrayList<>();

    public ChatAdapter(Context context){
        this.context = context;
        inflater = LayoutInflater.from(context);
    }
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == ChatBean.TYPE_RIGHT) {
            View view = inflater.inflate(R.layout.item_chat_right, parent, false);
            RightHolder rightHolder = new RightHolder(view);
            return rightHolder;
        }else if (viewType == ChatBean.TYPE_LEFT){
            View v = inflater.inflate(R.layout.item_chat_left,parent,false);
            LeftHolder leftHolder = new LeftHolder(v);
            return leftHolder;
        }
        return null;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof RightHolder) {
            RightHolder rightHolder = (RightHolder) holder;
            if (items != null) {
                rightHolder.tvChatContent.setText(items.get(position).getText());
                rightHolder.imgChatHead.setImageURI(Uri.parse(items.get(position).getHeadUrl()));
            }
        }else if (holder instanceof LeftHolder){
            LeftHolder leftHolder = (LeftHolder) holder;
            if (items!=null){
                leftHolder.tvChatContent.setText(items.get(position).getText());
            }
        }
    }

    @Override
    public int getItemCount() {
        if (items!=null)
            return items.size();
        else
            return 0;
    }

    @Override
    public int getItemViewType(int position) {
        return items.get(position).getType();
    }

    public void addMsg(ChatBean msg){
        items.add(msg);
        notifyItemInserted(items.size());
    }

    public class RightHolder extends RecyclerView.ViewHolder {
        private TextView tvChatContent;
        private SimpleDraweeView imgChatHead;
        public RightHolder(View itemView) {
            super(itemView);
            tvChatContent = (TextView) itemView.findViewById(R.id.tv_chat_right);
            imgChatHead = (SimpleDraweeView) itemView.findViewById(R.id.img_chat_head_right);
        }
    }

    public class LeftHolder extends RecyclerView.ViewHolder {
        private TextView tvChatContent;
        private SimpleDraweeView imgChatHead;
        public LeftHolder(View itemView) {
            super(itemView);
            tvChatContent = (TextView) itemView.findViewById(R.id.tv_chat_left);
            imgChatHead = (SimpleDraweeView) itemView.findViewById(R.id.img_chat_head_left);
        }
    }
}

截图

Screenshot_2016-02-22-13-15-09.png

知晓了原理就很容易实现其他效果了，比如对RecyclerView添加头部（banner的展示效果），添加尾部（上拉加载更多），也可以实现新版知乎那样的列表中显示不同的item（有的是文字 有的是图片），只要在需要加载其他类型的item时对item的type进行判断，其他的逻辑判断自己处理好就没问题啦~