Android RecyclerView使用详解

简介

RecyclerView是Google在android-supportv7包中推出的一个新的控件，该控件的主要作用是用于替代ListView、GridView，相比较于这两种控件RecyclerView有以下有点：

• RecyclerView内部封装了ViewHolder,更加方便Item的复用
• 提供了一种插拔式的体验，高度解耦，异常灵活，增加控件的扩展性。

RecyclerView的灵活性可以体现在以下几点

• 通过RecyclerView.setLayoutManager()方法添加布局管理器
• 通过RecyclerView.addItemDecoration()方法添加item分割线
• 通过RecyclerView.setItemAnimator()方法添加item增删动画

LayoutManager布局管理器介绍

• LinearLayoutManager：线性布局
• GridLayoutManager：网格布局
• StaggeredGridLayoutManager：瀑布流布局

RecyclerView使用

导入类库

• 对于使用eclipse开发用户，需要导入sdk/extras/android/support/v7目录下recyclerview类库
• 对于Android studio开发用户,直接通过修改build.gradle添加类库即可

通过RecyclerView实现ListView：

效果如下：

实现代码如下：

package com.example.zhangke.recyclerviewdemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
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.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private ArrayList mDatas;
    private RecyclerViewAdapter mAdapter;
    private StaggeredGridLayoutAdapter mStagAdapter;
    private RecyclerView.ItemDecoration mItemDecoration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mRecyclerView = (RecyclerView) findViewById(R.id.recycleview);
        initData();

        //垂直listview
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        //设置分割线
        mItemDecoration = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL);
        mRecyclerView.addItemDecoration(mItemDecoration);
        // 设置增删动画
        mRecyclerView.setItemAnimator(new DefaultItemAnimator());

        mAdapter = new RecyclerViewAdapter(this, mDatas);

        //设置点击事件
        mAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(View view, int position) {
                Toast.makeText(MainActivity.this, "onItemClick " + position, Toast.LENGTH_SHORT).show();
            }
        });

        mAdapter.setOnLongItemClickListener(new RecyclerViewAdapter.OnLongItemClickListener() {
            @Override
            public void onLongItemClick(View view, int position) {
                Toast.makeText(MainActivity.this, "onLongItemClick " + position, Toast.LENGTH_SHORT).show();
            }
        });

        //设置Adapter
        mRecyclerView.setAdapter(mAdapter);

    }

    /**
     * 初始化数据
     */
    private void initData() {
        mDatas = new ArrayList();
        for (int i = 0; i < 100; i++) {
            mDatas.add("item " + i);
        }

    }


    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        switch (item.getItemId()) {
            case R.id.add:
                mAdapter.addItem(1, "item" + 1);
                break;
            case R.id.remove:
                mAdapter.removeItem(1);
                break;

        }
        return true;
    }
}

RecyclerView.Adapter说明

同ListView一样，RecyclerView现实数据需要通过Adapter实现，Google已给我们提供了RecyclerView.Adapter的内部抽象类，所以必须通过继承该类实现一个Adapter。继承该类需要复写三个方法：

1. public int getItemCount()：获得item数目
2. public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType)：创建一个ViewHolder
3. public void onBindViewHolder(final RecyclerViewHolder holder, int position)：绑定Viewholder即对Item进行具体操作

注意：由于Adapter会在内部封装一个ViewHolder，所以我们还要自定义一个ViewHolder。

RecyclerView item点击事件

对于RecyviewView，系统并没有提供item点击事件，所以在自定义Adapter时，通常会自己定义Item的点击事件的接口以实现item点击。

具体代码如下：

package com.example.zhangke.recyclerviewdemo;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.text.Layout;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * Created by zhangke on 16/6/15.
 */
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.RecyclerViewHolder> {


    private Context mContext;
    private ArrayList mDatas;
    private OnItemClickListener mOnItemClickListener;
    private OnLongItemClickListener mOnLongItemClickListener;

    public RecyclerViewAdapter(Context context, ArrayList datas) {
        this.mContext = context;
        this.mDatas = datas;
    }


    @Override
    public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        RecyclerViewHolder holder = new RecyclerViewHolder(View.inflate(mContext, R.layout.item, null));
        return holder;
    }

    @Override
    public void onBindViewHolder(final RecyclerViewHolder holder, int position) {
        holder.mTextView.setText(mDatas.get(position));
        if (mOnItemClickListener != null) {
            holder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    int layoutPosition = holder.getLayoutPosition();
                    mOnItemClickListener.onItemClick(v, layoutPosition);
                }
            });
        }
        if (mOnLongItemClickListener != null) {
            holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    int layoutPosition = holder.getLayoutPosition();
                    mOnLongItemClickListener.onLongItemClick(v, layoutPosition);
                    return true;
                }
            });
        }
    }

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

    /**
     * viewholder
     */
    class RecyclerViewHolder extends RecyclerView.ViewHolder {

        private TextView mTextView;

        public RecyclerViewHolder(View itemView) {
            super(itemView);

            mTextView = (TextView) itemView.findViewById(R.id.textview);
        }
    }

    /**
     * 添加
     * @param position
     * @param item
     */
    public void addItem(int position, String item){
        mDatas.add(position, item+position);
        notifyItemInserted(position);
    }

    /**
     * 删除
     * @param position
     */
    public void removeItem(int position){
        mDatas.remove(position);
        notifyItemRemoved(position);
    }

    /**
     * item点击事件
     */
    public interface OnItemClickListener {
        /**
         * item点击事件
         *
         * @param view
         * @param position
         */
        void onItemClick(View view, int position);
    }

    public interface OnLongItemClickListener {
        /**
         * item长按点击事件
         *
         * @param view
         * @param position
         */
        void onLongItemClick(View view, int position);
    }


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

    public void setOnLongItemClickListener(OnLongItemClickListener listener) {
        this.mOnLongItemClickListener = listener;
    }
}

ItemDecoration分割线

在之前已经提到，RecyclerView有addItemDecoration()的方法，该方法的作用是为RecyclerView添加item分割线，为此我们不难想象RecyclerView默认是没有分割线的。但是google官方并没有提供具体ItemDecoration的方法，仅仅是定义了一个ItemDecoration的抽象类，所以要想实现分割线效果，必须要自己实现一个ItemDecoration。

ItemDecoration抽象方法介绍：

1. public void onDraw(Canvas c, RecyclerView parent, State state)：绘制分割线
2. public void onDrawOver(Canvas c, RecyclerView parent, State state)：绘制分割线，该方法后于onDraw，一般实现一个即可
3. public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state)：用于计算item分割线的偏移量

以下是通过ItemDecoration实现ListView和GridView的分割线：

ListView分割线：

package com.example.zhangke.recyclerviewdemo;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;

/**
 * item分割线
 * 

 * Created by zhangke on 16/6/15.
 */
public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    /**
     * 分割线
     */
    private static int[] ATTRS = new int[]{android.R.attr.listDivider};

    /**
     * 水平分割线
     */
    public static final int HORIZONTAL = LinearLayoutManager.HORIZONTAL;
    /**
     * 垂直分割线
     */
    public static final int VERTICAL = LinearLayoutManager.VERTICAL;
    /**
     * 上下文
     */
    private Context mContext;
    /**
     * 分割线
     */
    private Drawable mDivider;

    private int mOrientation;

    /**
     * @param context     上下文
     * @param orientation 分割线方向
     */
    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public DividerItemDecoration(Context context, int orientation) {
        this.mContext = context;
//        TypedArray typedArray = mContext.obtainStyledAttributes(ATTRS);
//        mDivider = typedArray.getDrawable(0);
//        typedArray.recycle();

        mDivider = context.getDrawable(R.drawable.divider_view);
        setOrientation(orientation);
    }

    /**
     * 设置分割线方向
     *
     * @param orientation
     */
    private void setOrientation(int orientation) {
        if (orientation != HORIZONTAL && orientation != VERTICAL) {
            throw new IllegalArgumentException("参数异常");
        }
        this.mOrientation = orientation;
    }


    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == HORIZONTAL) {
            drawHorizontal(c, parent, state);
        } else {
            drawVertical(c, parent, state);
        }

        super.onDraw(c, parent, state);
    }

    /**
     * 绘制垂直方向分割线
     *
     * @param c
     * @param parent
     * @param state
     */
    private void drawVertical(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();

        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View childView = parent.getChildAt(i);

            RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) childView.getLayoutParams();
            int top = childView.getBottom() + layoutParams.bottomMargin + Math.round(ViewCompat.getTranslationY(childView));
            int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    /**
     * 绘制水平方向分割线
     *
     * @param c
     * @param parent
     * @param state
     */
    private void drawHorizontal(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int top = parent.getPaddingTop();
        int bottom = parent.getHeight() - parent.getPaddingBottom();

        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View childView = parent.getChildAt(i);
            RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) childView.getLayoutParams();
            int left = childView.getRight() + layoutParams.rightMargin + Math.round(ViewCompat.getTranslationX(childView));
            int right = left + mDivider.getIntrinsicWidth();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    /**
     * 设置分割线宽偏移量:
     * 通过RecyclerView源码可知：getItemOffset方法会在measureChild方法中调用，我们通过给方法的参数outRect
     * 设置left、top、right、bottom，设置的值会被增加到childView的padding值中。
     *
     * @param outRect
     * @param view
     * @param parent
     * @param state
     */
    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {

        if (mOrientation == HORIZONTAL) {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        } else {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        }
    }


}

GridView分割线：

package com.example.zhangke.recyclerviewdemo;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;

/**
 * item分割线
 * 

 * Created by zhangke on 16/6/15.
 */
public class DividerGridItemDecoration extends RecyclerView.ItemDecoration {

    /**
     * 分割线
     */
    private static int[] ATTRS = new int[]{android.R.attr.listDivider};

    /**
     * 水平分割线
     */
    public static final int HORIZONTAL = LinearLayoutManager.HORIZONTAL;
    /**
     * 垂直分割线
     */
    public static final int VERTICAL = LinearLayoutManager.VERTICAL;
    /**
     * 上下文
     */
    private Context mContext;
    /**
     * 分割线
     */
    private Drawable mDivider;

    private int mOrientation;
    private int spanCount;

    /**
     * @param context     上下文
     * @param orientation 分割线方向
     */
    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public DividerGridItemDecoration(Context context, int orientation) {
        this.mContext = context;
//        TypedArray typedArray = mContext.obtainStyledAttributes(ATTRS);
//        mDivider = typedArray.getDrawable(0);
//        typedArray.recycle();

        mDivider = context.getDrawable(R.drawable.divider_view);
        setOrientation(orientation);
    }

    /**
     * 设置分割线方向
     *
     * @param orientation
     */
    private void setOrientation(int orientation) {
        if (orientation != HORIZONTAL && orientation != VERTICAL) {
            throw new IllegalArgumentException("参数异常");
        }
        this.mOrientation = orientation;
    }


    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        drawHorizontal(c, parent, state);
        drawVertical(c, parent, state);
    }

    /**
     * 绘制垂直方向分割线
     *
     * @param c
     * @param parent
     * @param state
     */
    private void drawVertical(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
            RecyclerView.LayoutParams params = (GridLayoutManager.LayoutParams) child.getLayoutParams();
            int left = child.getLeft() - params.leftMargin;
            int right = child.getRight()+ params.rightMargin;
            int top = child.getBottom() + params.bottomMargin;
            int bottom = top + mDivider.getIntrinsicHeight();

            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }

    }

    /**
     * 绘制水平方向分割线
     *
     * @param c
     * @param parent
     * @param state
     */
    private void drawHorizontal(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
            RecyclerView.LayoutParams params = (GridLayoutManager.LayoutParams) child.getLayoutParams();
            int left = child.getRight() + params.rightMargin;
            int right = left + mDivider.getIntrinsicWidth();
            int top = child.getTop() - params.topMargin;
            int bottom = child.getBottom() + params.bottomMargin;

            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    /**
     * 设置分割线宽偏移量:
     * 通过RecyclerView源码可知：getItemOffset方法会在measureChild方法中调用，我们通过给方法的参数outRect
     * 设置left、top、right、bottom，设置的值会被增加到childView的padding值中。
     */
    @Override
    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
        if (isLastColum(itemPosition, parent)) {
            //最后一列
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else if (isLastRow(itemPosition, parent)) {
            //最后一行
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), mDivider.getIntrinsicHeight());
        }

    }

    /**
     * 是否是最后一行
     *
     * @param itemPosition
     * @param parent
     * @return
     */
    private boolean isLastRow(int itemPosition, RecyclerView parent) {
        int spanCount = getSpanCount(parent);
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            int childCount = parent.getAdapter().getItemCount();

            int lastRowCount = childCount %  spanCount;
            if (lastRowCount == 0) {
                return false;
            } else if(itemPosition >= (childCount - lastRowCount)){
                return true;
            }
        }
        return false;
    }

    /*
    * 是否是最后一列
     */
    private boolean isLastColum(int itemPosition, RecyclerView parent) {
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            int spanCount = getSpanCount(parent);
            if ((itemPosition + 1) % spanCount == 0) {
                return true;
            }
        }
        return false;
    }

    private int getSpanCount(RecyclerView parent) {
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            GridLayoutManager lm = (GridLayoutManager) layoutManager;
            int spanCount = lm.getSpanCount();
            return spanCount;
        }
        return 0;
    }

}

通过LayoutManager实现不同效果

效果图如下：

代码如下：

package com.example.zhangke.recyclerviewdemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
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.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private ArrayList mDatas;
    private RecyclerViewAdapter mAdapter;
    private StaggeredGridLayoutAdapter mStagAdapter;
    private RecyclerView.ItemDecoration mItemDecoration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mRecyclerView = (RecyclerView) findViewById(R.id.recycleview);
        initData();

        //垂直listview
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        //设置分割线
        mItemDecoration = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL);
        mRecyclerView.addItemDecoration(mItemDecoration);
        // 设置增删动画
        mRecyclerView.setItemAnimator(new DefaultItemAnimator());

        mAdapter = new RecyclerViewAdapter(this, mDatas);

        //设置点击事件
        mAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(View view, int position) {
                Toast.makeText(MainActivity.this, "onItemClick " + position, Toast.LENGTH_SHORT).show();
            }
        });

        mAdapter.setOnLongItemClickListener(new RecyclerViewAdapter.OnLongItemClickListener() {
            @Override
            public void onLongItemClick(View view, int position) {
                Toast.makeText(MainActivity.this, "onLongItemClick " + position, Toast.LENGTH_SHORT).show();
            }
        });

        //设置Adapter
        mRecyclerView.setAdapter(mAdapter);

    }

    /**
     * 初始化数据
     */
    private void initData() {
        mDatas = new ArrayList();
        for (int i = 0; i < 100; i++) {
            mDatas.add("item " + i);
        }

    }


    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (mItemDecoration != null) {
            mRecyclerView.removeItemDecoration(mItemDecoration);
        }
        switch (item.getItemId()) {
            case R.id.add:

                mAdapter.addItem(1, "item" + 1);
                break;

            case R.id.remove:
                mAdapter.removeItem(1);
                break;

            case R.id.showVertical:
                //垂直listview
                mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
                mItemDecoration = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL);
                mRecyclerView.addItemDecoration(mItemDecoration);
                mAdapter = new RecyclerViewAdapter(this, mDatas);
                mAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {
                    @Override
                    public void onItemClick(View view, int position) {
                        Toast.makeText(MainActivity.this, "onItemClick " + position, Toast.LENGTH_SHORT).show();
                    }
                });

                mAdapter.setOnLongItemClickListener(new RecyclerViewAdapter.OnLongItemClickListener() {
                    @Override
                    public void onLongItemClick(View view, int position) {
                        Toast.makeText(MainActivity.this, "onLongItemClick " + position, Toast.LENGTH_SHORT).show();
                    }
                });

                mRecyclerView.setAdapter(mAdapter);
                break;

            case R.id.showHorizontal:
                //水平listview
                mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
                mItemDecoration = new DividerItemDecoration(this, DividerItemDecoration.HORIZONTAL);
                mRecyclerView.addItemDecoration(mItemDecoration);
                mAdapter = new RecyclerViewAdapter(this, mDatas);
                mRecyclerView.setAdapter(mAdapter);
                break;

            case R.id.showGridHorizontal:
                // 水平gridview
                mRecyclerView.setLayoutManager(new GridLayoutManager(this, 4, LinearLayoutManager.HORIZONTAL, false));
                mItemDecoration = new DividerGridItemDecoration(this, DividerGridItemDecoration.HORIZONTAL);
                mRecyclerView.addItemDecoration(mItemDecoration);
                mAdapter = new RecyclerViewAdapter(this, mDatas);
                mRecyclerView.setAdapter(mAdapter);
                break;

            case R.id.showGridVertical:
                // 垂直gridview
                mRecyclerView.setLayoutManager(new GridLayoutManager(this, 4));
                mItemDecoration = new DividerGridItemDecoration(this, DividerGridItemDecoration.VERTICAL);
                mRecyclerView.addItemDecoration(mItemDecoration);
                mAdapter = new RecyclerViewAdapter(this, mDatas);
                mRecyclerView.setAdapter(mAdapter);
                break;

            case R.id.showStaggle:
                // 瀑布流
                mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(3, LinearLayoutManager.VERTICAL));
                mStagAdapter = new StaggeredGridLayoutAdapter(this, mDatas);
                mRecyclerView.setAdapter(mStagAdapter);
                break;
        }
        return true;
    }
}

源代码：
https://github.com/kerwin1321/Study/tree/master/MaterialDesign/RecyclerView