RecyclerView详解

不说废话:直接代码

package com.example.recyclerveiwdemo;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.View;

import com.example.recyclerveiwdemo.adapter.MyAdapter;


public class MainActivity extends AppCompatActivity {

    private RecyclerView recyclerView;
    private MyAdapter myAdapter;
    private LinearLayoutManager linearLayoutManager;
    private GridLayoutManager gridLayoutManager;
    private StaggeredGridLayoutManager staggeredGridLayoutManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        recyclerView = (RecyclerView) findViewById(R.id.recyclerView);

        //listView的形式展示
        linearLayoutManager = new LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);

        //gridview的形式展示,可以通过setSpanSizeLookup 来自定义每个item占的列数
        gridLayoutManager = new GridLayoutManager(this, 3);
        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                return 3 - position % 3;
            }
        });

        //瀑布流的形式
        staggeredGridLayoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);

        recyclerView.setLayoutManager(linearLayoutManager);
        myAdapter = new MyAdapter();
        recyclerView.setAdapter(myAdapter);

        myAdapter.setOnItemClickListener(new MyAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(View v, int position) {

                //增加和删除的话 不直接对postion做处理,因为此处的position是没有刷新以前的position
                myAdapter.add(position);
            }
        });

        myAdapter.setOnItemLongClickListener(new MyAdapter.OnItemLongClickListener() {
            @Override
            public void onItemLongClick(View v, int position) {

                //remove的操作
//                myAdapter.remove(position);

                //更新的操作
                myAdapter.updata(position,"这是我更新的内容");
            }
        });
        recyclerView.addItemDecoration(new MyDecoration(this,LinearLayoutManager.VERTICAL));
    }


    public void onClick(View v) {

        //切换布局
        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
        if (layoutManager == null) {
            return;
        }

        //if和elseif是有先后顺序的,先判断范围小的,然后再判断范围大的,
        //因为GridLayoutManager 是继承 LinearLayoutManager ,所以他本质上也是LinearLayoutManager,
        //所以不能先判断是否是LinearLayoutManager (LinearLayoutManager范围大)
        if (layoutManager instanceof GridLayoutManager) {
            recyclerView.setLayoutManager(linearLayoutManager);
        } else if (layoutManager instanceof LinearLayoutManager) {
            recyclerView.setLayoutManager(gridLayoutManager);
        }
    }
}

package com.example.recyclerveiwdemo;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;

/**
 * Created by hasee on 2017/8/31.
 */

public class MyDecoration extends RecyclerView.ItemDecoration {

    private Context mContext;
    private Drawable mDivider;
    private int mOrientation;
    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

    //我们通过获取系统属性中的listDivider来添加，在系统中的AppTheme中设置
    public static final int[] ATRRS = new int[]{
            android.R.attr.listDivider
    };

    public MyDecoration(Context context, int orientation) {
        this.mContext = context;
        final TypedArray ta = context.obtainStyledAttributes(ATRRS);
        this.mDivider = ta.getDrawable(0);
        ta.recycle();
        setOrientation(orientation);
    }

    //设置屏幕的方向
    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
            throw new IllegalArgumentException("invalid orientation");
        }
        mOrientation = orientation;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == HORIZONTAL_LIST) {
            drawVerticalLine(c, parent, state);
        } else {
            drawHorizontalLine(c, parent, state);
        }
    }

    //画横线, 这里的parent其实是显示在屏幕显示的这部分
    public void drawHorizontalLine(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);

            //获得child的布局信息
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left+params.leftMargin, top, right-params.leftMargin, bottom);

            mDivider.draw(c);
            //Log.d("wnw", left + " " + top + " "+right+"   "+bottom+" "+i);
        }
    }

    //画竖线
    public void drawVerticalLine(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int top = parent.getPaddingTop();
        int bottom = parent.getHeight() - parent.getPaddingBottom();
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);

            //获得child的布局信息
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicWidth();
            mDivider.setBounds(left, top+params.topMargin, right, bottom-params.topMargin);
            mDivider.draw(c);
        }
    }

    //由于Divider也有长宽高，每一个Item需要向下或者向右偏移
    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == HORIZONTAL_LIST) {
            //画横线，就是往下偏移一个分割线的高度
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            //画竖线，就是往右偏移一个分割线的宽度
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }
}

package com.example.recyclerveiwdemo.adapter;

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.recyclerveiwdemo.R;

import java.util.ArrayList;

/**
 * Created by hasee on 2017/8/30.
 */

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {

    ArrayList<String> list;

    public MyAdapter() {
        list = new ArrayList<>();
        for (int i = 0; i < 30; i++) {
            list.add("条目 " + i);
        }
    }

    //创建布局和viewHolder
    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        //inflate的时候,需要传入parent和attachToRoot==false; 使用传入三个参数的方法
        View recyclerViewItem = LayoutInflater.from(parent.getContext()).inflate(R.layout.recycler_view_item, parent, false);
        return new MyViewHolder(recyclerViewItem);
    }

    //增加的方法
    public void add(int position) {

        //改变数据
        list.add(position + 1, "这是新加的");

        //调用它带的方法去刷新
        notifyItemRangeChanged(position + 1, getItemCount());
    }

    public void remove(int position) {
        list.remove(position);
        notifyItemRangeRemoved(position, getItemCount());
    }


    public void updata(int position, String content) {
        list.remove(position);
        list.add(position, content);
        notifyItemChanged(position);
    }


    //单击事件的接口
    public interface OnItemClickListener {
        void onItemClick(View v, int position);
    }

    //长按事件的接口
    public interface OnItemLongClickListener {
        void onItemLongClick(View v, int position);
    }

    private OnItemClickListener mItemClickListener;
    private OnItemLongClickListener mItemLongClickListener;

    //设置单击事件的接口
    public void setOnItemClickListener(OnItemClickListener itemClickListener) {
        mItemClickListener = itemClickListener;
    }

    //设置长按事件的接口
    public void setOnItemLongClickListener(OnItemLongClickListener itemLongClickListener) {
        mItemLongClickListener = itemLongClickListener;
    }

    //绑定数据
    @Override
    public void onBindViewHolder(MyViewHolder holder, final int position) {
        holder.title.setText(list.get(position));

        //整个item条目的点击
//        holder.itemView.setOnClickListener(new View.OnClickListener() {
//            @Override
//            public void onClick(View v) {
//                //// TODO: 2017/8/31 暴露一个单击回调接口
//                if (mItemClickListener != null) {
//                    mItemClickListener.onItemClick(v, position);
//                }
//            }
//        });

        holder.icon.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //// TODO: 2017/8/31 暴露一个单击回调接口
                if (mItemClickListener != null) {
                    mItemClickListener.onItemClick(v, position);
                }
            }
        });

        holder.icon.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View v) {

                if (mItemLongClickListener != null) {
                    mItemLongClickListener.onItemLongClick(v, position);
                }
                // true 消费这个长按事件
                return true;
            }
        });


    }

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


    public class MyViewHolder extends RecyclerView.ViewHolder {


        //把整个view放到viewHolder中
        View itemView;
        TextView title;
        ImageView icon;

        //findviewById 给控件绑定id
        public MyViewHolder(View itemView) {
            super(itemView);
            this.itemView = itemView;
            title = (TextView) itemView.findViewById(R.id.title);
            icon = (ImageView) itemView.findViewById(R.id.icon);
        }
    }
}