RecyclerView的簡單應用3：瀑布流

實現瀑布流，步驟和listview差不多，詳情看：
http://blog.csdn.net/qq_18148011/article/details/52602096

主要不同的地方在於：
1、adapter，代碼如下

package com.yztc.adapter;

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

import com.yztc.android0801.R;
import com.yztc.tools.OnItemClickListener;

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

/**
 * Created by ThinkPad-PC on 2016/9/20.
 */
public class MyStaggeredAdapter extends RecyclerView.Adapter<MyStaggeredAdapter.MyViewHolder> {

    private List<String> list;
    //模擬數據
    private List<Integer> heights;
    private Context context;
    private OnItemClickListener listener;

    public void setListener(OnItemClickListener listener) {
        this.listener = listener;
    }

    public MyStaggeredAdapter(Context context, List<String> list) {
        this.context = context;
        this.list = list;
        getRandomHeight(list);
    }

    //定義函數 採用隨機數定義item的高度
    public void getRandomHeight(List<String> list) {
        heights = new ArrayList<>();
        for (int i = 0; i < list.size(); i++) {
            heights.add((int) (Math.random() * 300 + 100));
        }
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.staggered_item,parent,false);
        MyViewHolder holder = new MyViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(final MyViewHolder holder, int position) {
        ViewGroup.LayoutParams params = holder.itemView.getLayoutParams();

        if (params != null)
            params.height = heights.get(position);
        else{
            Log.e("asd","sadsad");
        }

        holder.itemView.setLayoutParams(params);

        holder.tv.setText(list.get(position));
        if (listener != null) {
            holder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    int pos = holder.getLayoutPosition();
                    listener.OnItemClickListener(holder.itemView, pos);
                }
            });

            holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    int pos = holder.getLayoutPosition();
                    listener.OnItemLongClickListener(holder.itemView, pos);
                    return true;
                }
            });
        }
    }

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

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView tv;

        public MyViewHolder(View itemView) {
            super(itemView);
            tv = (TextView) itemView.findViewById(R.id.tv);
        }
    }
}

2、在初始化的時候多一句：
recyclerView.addItemDecoration(new SpacesItemDecoration(15));

以下是SpacesItemDecoration的代碼

package com.yztc.tools;

import android.graphics.Rect;
import android.support.v7.widget.RecyclerView;
import android.view.View;

/**
 * 設置item之間的分割空間
 */
public class SpacesItemDecoration extends RecyclerView.ItemDecoration {

    private int space;

    public SpacesItemDecoration(int space) {
        this.space=space;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        outRect.left = space;
        outRect.right = space;
        outRect.bottom = space;
        if(parent.getChildPosition(view) == 0 || parent.getChildPosition(view) == 1 || parent.getChildPosition(view) == 2 || parent.getChildPosition(view) == 3){
            outRect.top = space;
        }
    }
}

完成：