RecyclerView的那点事儿

RecyclerView

控件简单介绍

• ListView的升级版
• LinearLayoutManager
• GridLayoutManager
• StaggeredGridLayoutManager
• 定制Item动画，指定Item之间的分隔线

RecyclerView相关的重要类

• Adapter
• ViewHolder
• LayoutManager
• ItemDecoration
• ItemAnimator

加入RecyclerView控件依赖包

Android Studio开发工具，在本项目的build.gradle文件里加入

  compile 'com.android.support:recyclerview-v7:23.1.1'

假设是eclipse的话，下载jar包。放到lib下。一般都会自己主动的build path,检查下就可以。

怎样下载jar ?
在SDK Manager中下载Support Library

sdkextrasandroidsupportv7 ecyclerviewlibs

为Recycler准备数据

package demo.turing.com.materialdesignwidget.recyclerView;

import java.util.ArrayList;

import demo.turing.com.materialdesignwidget.recyclerView.model.SampleModel;

/**
 * MyApp
 *
 * @author Mr.Yang on 2016-03-30  20:21.
 * @version 1.0
 * @desc
 */
public class SimulatorData {


    public static ArrayList<SampleModel> getSampleModelData(int size) {

        ArrayList<SampleModel> sampleData = new ArrayList<SampleModel>(size);

        for (int i = 0; i < size; i++) {
            sampleData.add(new SampleModel("新的列表项< " + i + " >"));
        }

        return sampleData;
    }

}

package demo.turing.com.materialdesignwidget.recyclerView.model;

/**
 * MyApp
 *
 * @author Mr.Yang on 2016-03-30  20:23.
 * @version 1.0
 * 相应Item中药显示的数据项
 */
public class SampleModel {



    private String text;


    public SampleModel(String text) {
        this.text = text;
    }


    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }
}

绘制列表项之间的分隔线

package demo.turing.com.materialdesignwidget.recyclerView;

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;

/**
 * MyApp
 *
 * @author Mr.Yang on 2016-03-30  20:37.
 * @version 1.0
 *          分隔条
 *
 *
 *   DividerItemDecoration  https://gist.github.com/alexfu/0f464fc3742f134ccd1e
 */
public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    // 默认分隔条Drawable资源的ID,使用系统自带的
    private static final int[] ATTRS = new int[]{android.R.attr.listDivider};

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;

    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;


    private Drawable mDivider;

    private int mOrientation;

    public DividerItemDecoration(Context context, int orientation) {
        // 使用TypedArray装载定义的ATTRS
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        // 获取系统提供的分隔条Drawable对象
        mDivider = a.getDrawable(0);
        // 回收TypedArray所占用的空间
        a.recycle();
        setOrientation(orientation);
    }


    /**
     * 设置item的显示 水平 or 垂直
     *
     * @param orientation
     */
    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) {
        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }
    }

    public void drawVertical(Canvas c, RecyclerView parent) {
        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();

        final int childCount = parent.getChildCount();

        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            RecyclerView v = new android.support.v7.widget.RecyclerView(
                    parent.getContext());
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getHeight() - parent.getPaddingBottom();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, int itemPosition,
                               RecyclerView parent) {
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }

}

实现Adapter

package demo.turing.com.materialdesignwidget.recyclerView.adapter;

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

import java.util.ArrayList;
import java.util.Random;

import demo.turing.com.materialdesignwidget.R;
import demo.turing.com.materialdesignwidget.recyclerView.SimulatorData;
import demo.turing.com.materialdesignwidget.recyclerView.model.SampleModel;

/**
 * MyApp
 *
 * @author Mr.Yang on 2016-03-30  21:03.
 * @version 1.0
 * @desc
 */
public class SampleRecyclerAdapter extends RecyclerView.Adapter<SampleRecyclerAdapter.ViewHolder> {

    // 模拟数据
    private  ArrayList<SampleModel> sampleData = SimulatorData.getSampleModelData(20);

    /**
     * 用于创建控件
     *
     * @param parent
     * @param viewType
     * @return
     */
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        // 获得列表项控件（LinearLayer对象）

        // list_basic_item.xml布局文件里仅仅包括一个<LinearLayer>标签，
        // 在该标签中包括了一个<TextView>标签, item是LinearLayout对象
        View item = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.list_basic_item, parent, false);

        ViewHolder viewHolder = new ViewHolder(item);

        return viewHolder;
    }

    /**
     * 为控件设置数据
     *
     * @param holder
     * @param position
     */
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {

        //  获取当前item中显示的数据
        final SampleModel rowData = sampleData.get(position);

        //  设置要显示的数据
        holder.textViewSample.setText(rowData.getText());
        // 设置tag
        holder.itemView.setTag(rowData);

    }


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


    /**
     * 删除指定的Item
     *
     * @param position
     */
    public void removeData(int position) {
        sampleData.remove(position);
        //  通知RecyclerView控件某个Item已经被删除
        notifyItemRemoved(position);

    }


    /**
     * 在指定位置加入一个新的Item
     *
     * @param positionToAdd
     */
    public void addItem(int positionToAdd) {
        sampleData.add(positionToAdd, new SampleModel("新的列表项" + new Random().nextInt(10000)));
        //  通知RecyclerView控件插入了某个Item
        notifyItemInserted(positionToAdd);
    }


    /**
     * 相应Item中的控件
     */
    public static class ViewHolder extends RecyclerView.ViewHolder {

        private final TextView textViewSample;

        public ViewHolder(View itemView) {
            super(itemView);
            textViewSample = (TextView) itemView
                    .findViewById(R.id.textViewSample);
        }
    }


}

完毕使用RecyclerView控件的最后工作

package demo.turing.com.materialdesignwidget.recyclerView;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

import demo.turing.com.materialdesignwidget.R;
import demo.turing.com.materialdesignwidget.recyclerView.adapter.SampleRecyclerAdapter;

public class RecyclerViewAct extends AppCompatActivity {


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

        // 获取RecyclerView对象
        RecyclerView recyclerView = (RecyclerView)findViewById(R.id.recycler_view);

        //  创建线性布局管理器（默认是垂直方向）
        LinearLayoutManager layoutManager = new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);


        //  为RecyclerView指定布局管理对象
        recyclerView.setLayoutManager(layoutManager);

        //  创建列表项分隔线对象
        RecyclerView.ItemDecoration itemDecoration = new DividerItemDecoration(this,DividerItemDecoration.VERTICAL_LIST);

        //  为RecyclerView控件指定分隔线对象
        recyclerView.addItemDecoration(itemDecoration);

        SampleRecyclerAdapter sampleRecyclerAdapter = new SampleRecyclerAdapter();
        recyclerView.setAdapter(sampleRecyclerAdapter);


    }


}

效果图

定制个性化分隔条

drawabledivider_custom.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <size android:height="4dp"></size>
    <!--渐变色-->
    <gradient
        android:centerColor="#ff0000ff"
        android:endColor="#ffff0000"
        android:startColor="#ffff0000"
        android:type="linear"></gradient>


</shape>

主题中设置

  <item name="android:listDivider">@drawable/divider_custom</item>

瀑布流

StaggeredGridLayuoutAct.java

package demo.turing.com.materialdesignwidget.recyclerView;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;

import java.util.List;

import demo.turing.com.materialdesignwidget.R;
import demo.turing.com.materialdesignwidget.recyclerView.adapter.StaggeredGridLayoutAdapter;
import demo.turing.com.materialdesignwidget.recyclerView.model.SampleModel;


/**
 * 不採用分隔线， 在Item的布局中 採用layout_margin的方式
 *
 * 主要是动态设置View的高度 adapter类中的 onBindViewHolder
 */

public class StaggeredGridLayuoutAct extends AppCompatActivity {

    private RecyclerView recyclerView ;

    // 模拟数据
    private List<SampleModel> sampleData = SimulatorData.getSampleModelData(20);



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

        // 查找组件
        recyclerView = (RecyclerView) findViewById(R.id.id_rv_staggered);

        // 创建布局管理器  -3列，垂直
        StaggeredGridLayoutManager manager = new StaggeredGridLayoutManager(3,StaggeredGridLayoutManager.VERTICAL);
        // 设置布局
        recyclerView.setLayoutManager(manager);

        // Adapter
        StaggeredGridLayoutAdapter adapter = new StaggeredGridLayoutAdapter(this,sampleData);
        recyclerView.setAdapter(adapter);




    }
}

activity_staggered_grid_layuout.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="demo.turing.com.materialdesignwidget.recyclerView.StaggeredGridLayuoutAct">


    <android.support.v7.widget.RecyclerView
        android:id="@+id/id_rv_staggered"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></android.support.v7.widget.RecyclerView>

</RelativeLayout>

StaggeredGridLayoutAdapter.java

package demo.turing.com.materialdesignwidget.recyclerView.adapter;

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

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

import demo.turing.com.materialdesignwidget.R;
import demo.turing.com.materialdesignwidget.recyclerView.model.SampleModel;

/**
 * MyApp
 *
 * @author Mr.Yang on 2016-03-31  20:19.
 * @version 1.0
 * @desc
 */
public class StaggeredGridLayoutAdapter extends RecyclerView.Adapter<StaggeredGridLayoutAdapter.ViewHolder> {


    private Context context;
    private List<SampleModel> datas;
    private LayoutInflater inflater;
    // 随机高度的结合
    private List<Integer> mHeights;

    /**
     * 构造函数
     *
     * @param context
     * @param datas
     */
    public StaggeredGridLayoutAdapter(Context context, List<SampleModel> datas) {
        this.context = context;
        this.datas = datas;
        this.inflater = LayoutInflater.from(context);


        // 初始化随机高度的集合
        mHeights = new ArrayList<>();
        for (int i = 0; i < datas.size(); i++) {
            mHeights.add((int)(100 + Math.random() * 300));
        }
    }

    @Override
    public StaggeredGridLayoutAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // 动态载入Item的布局文件
        View view = inflater.inflate(R.layout.list_basic_item, parent, false);
        // 实例化ViewHolder
        ViewHolder viewHolder = new ViewHolder(view);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(StaggeredGridLayoutAdapter.ViewHolder holder, int position) {


        // 获取当前Item中的显示的数据
        SampleModel sampleModel = datas.get(position);

        //设置控件的随机高度
        ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
        lp.height = mHeights.get(position);
        holder.itemView.setLayoutParams(lp);


        // 设置组件的值
        holder.textView.setText(sampleModel.getText());
        // 设置tag
        holder.itemView.setTag(sampleModel);

    }


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

    /**
     * ViewHoder
     */
    class ViewHolder extends RecyclerView.ViewHolder {

        TextView textView;

        public ViewHolder(View itemView) {
            super(itemView);
            textView = (TextView) itemView
                    .findViewById(R.id.textViewSample);
        }
    }
}

list_basic_item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="3dp"
    android:background="#6495ED"
    android:gravity="center"
    android:orientation="horizontal">

    <TextView
        android:id="@+id/textViewSample"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="20sp"
        android:text="演示"/>

</RelativeLayout>

效果图

动画效果

 // 默认动画效果
 recyclerView.setItemAnimator(new DefaultItemAnimator());

notifyItemRemoved(position)

 /**
     * 删除指定的Item
     *
     * @param position
     */
    public void removeData(int position) {
        sampleData.remove(position);
        //  通知RecyclerView控件某个Item已经被删除
        notifyItemRemoved(position);

    }

notifyItemInserted(positionToAdd)

    /**
     * 在指定位置加入一个新的Item
     *
     * @param positionToAdd
     */
    public void addItem(int positionToAdd) {
        sampleData.add(positionToAdd, new SampleModel("新的列表项" + new Random().nextInt(10000)));
        //  通知RecyclerView控件插入了某个Item
        notifyItemInserted(positionToAdd);
    }

为RecyclerView加入item的点击事件

方法一：利用回调的方式实现(不太完好，仍可实现)

实现过程例如以下：
在adapter类中，定义接口，接口中定义两个方法分别相应click和longClick，定义完接口。加入接口和设置Adapter接口的方法：

  /**
     * 接口 ，提供两个方法
     */
    public interface OnRecyclerViewItemClickListener{
        // 单击事件
        void onItemClick(View view ,int position);
        // 长按触发的事件
        void onItemLongClick(View view ,int position);
    }
    // 定义OnRecyclerViewItemClickListener对象
    public OnRecyclerViewItemClickListener  mOnRecyclerViewItemClickListener ;

    // 暴漏给外部的set方法。持有OnRecyclerViewItemClickListener对象
    public void setOnRecyclerViewItemClickListener(OnRecyclerViewItemClickListener listener){
        this.mOnRecyclerViewItemClickListener = listener ;
    }

在onBindViewHolder方法中

 // 点击事件
        if(mOnRecyclerViewItemClickListener != null){
            // click
            holder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    mOnRecyclerViewItemClickListener.onItemClick(holder.itemView,position);
                }
            });
            // longClick
            holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    mOnRecyclerViewItemClickListener.onItemLongClick(holder.itemView,position);
                    return false;
                }
            });

        }

做完这些事情，我们就能够在Activity或其它地方为RecyclerView加入项目点击事件了，

// 设置监事件
        sampleRecyclerAdapter.setOnRecyclerViewItemClickListener(new SampleRecyclerAdapter.OnRecyclerViewItemClickListener() {
            @Override
            public void onItemClick(View view, int position) {
                Toast.makeText(RecyclerViewAct.this,"Click" + position ,Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onItemLongClick(View view, int position) {
                Toast.makeText(RecyclerViewAct.this,"LongClick" + position ,Toast.LENGTH_SHORT).show();

            }
        });

完整代码例如以下：

RecyclerViewAct

package demo.turing.com.materialdesignwidget.recyclerView;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Toast;

import demo.turing.com.materialdesignwidget.R;
import demo.turing.com.materialdesignwidget.recyclerView.adapter.SampleRecyclerAdapter;

public class RecyclerViewAct extends AppCompatActivity {


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

        // 获取RecyclerView对象
        RecyclerView recyclerView = (RecyclerView)findViewById(R.id.recycler_view);

        //  创建线性布局管理器（默认是垂直方向）
        LinearLayoutManager layoutManager = new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);


        //  为RecyclerView指定布局管理对象
        recyclerView.setLayoutManager(layoutManager);

        //  创建列表项分隔线对象
        RecyclerView.ItemDecoration itemDecoration = new DividerItemDecoration(this,DividerItemDecoration.VERTICAL_LIST);

        //  为RecyclerView控件指定分隔线对象
        recyclerView.addItemDecoration(itemDecoration);



        // 默认动画效果
        recyclerView.setItemAnimator(new DefaultItemAnimator());


        SampleRecyclerAdapter sampleRecyclerAdapter = new SampleRecyclerAdapter();
        recyclerView.setAdapter(sampleRecyclerAdapter);



        // 设置监事件
        sampleRecyclerAdapter.setOnRecyclerViewItemClickListener(new SampleRecyclerAdapter.OnRecyclerViewItemClickListener() {
            @Override
            public void onItemClick(View view, int position) {
                Toast.makeText(RecyclerViewAct.this,"Click" + position ,Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onItemLongClick(View view, int position) {
                Toast.makeText(RecyclerViewAct.this,"LongClick" + position ,Toast.LENGTH_SHORT).show();

            }
        });
    }


}

SampleRecyclerAdapter

package demo.turing.com.materialdesignwidget.recyclerView.adapter;

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

import java.util.ArrayList;
import java.util.Random;

import demo.turing.com.materialdesignwidget.R;
import demo.turing.com.materialdesignwidget.recyclerView.SimulatorData;
import demo.turing.com.materialdesignwidget.recyclerView.model.SampleModel;

/**
 * MyApp
 *
 * @author Mr.Yang on 2016-03-30  21:03.
 * @version 1.0
 * @desc
 *
 *
 * RecyclerView  点击事件 请看http://jcodecraeer.com/a/anzhuokaifa/androidkaifa/2014/1118/2004.html
*/
public class SampleRecyclerAdapter extends RecyclerView.Adapter<SampleRecyclerAdapter.ViewHolder> {

    // 模拟数据
    private  ArrayList<SampleModel> sampleData = SimulatorData.getSampleModelData(20);


    /**
     * 接口 ，提供两个方法
     */
    public interface OnRecyclerViewItemClickListener{
        // 单击事件
        void onItemClick(View view ,int position);
        // 长按触发的事件
        void onItemLongClick(View view ,int position);
    }
    // 定义OnRecyclerViewItemClickListener对象
    public OnRecyclerViewItemClickListener  mOnRecyclerViewItemClickListener ;

    // 暴漏给外部的set方法。持有OnRecyclerViewItemClickListener对象
    public void setOnRecyclerViewItemClickListener(OnRecyclerViewItemClickListener listener){
        this.mOnRecyclerViewItemClickListener = listener ;
    }


    /**
     * 用于创建控件
     *
     * @param parent
     * @param viewType
     * @return
     */
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        // 获得列表项控件（LinearLayer对象）

        // list_basic_item.xml布局文件里仅仅包括一个<LinearLayer>标签，
        // 在该标签中包括了一个<TextView>标签, item是LinearLayout对象
        View item = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.list_basic_item, parent, false);

        ViewHolder viewHolder = new ViewHolder(item);

        return viewHolder;
    }

    /**
     * 为控件设置数据
     *
     * @param holder
     * @param position
     */
    @Override
    public void onBindViewHolder(final ViewHolder holder, final int position) {

        //  获取当前item中显示的数据
        final SampleModel rowData = sampleData.get(position);

        //  设置要显示的数据
        holder.textViewSample.setText(rowData.getText());
        // 设置tag
        holder.itemView.setTag(rowData);

         // 点击事件
 if(mOnRecyclerViewItemClickListener != null){
            // click
        holder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    // 通过getLayoutPosition，防止position错位
                    int layoutPosition = holder.getLayoutPosition();
                    mOnRecyclerViewItemClickListener.onItemClick(holder.itemView,layoutPosition);
                }
            });
            // longClick
            holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    int layoutPosition = holder.getLayoutPosition();
                    mOnRecyclerViewItemClickListener.onItemLongClick(holder.itemView,layoutPosition);
                    return false;
                }
            });
        }
    }


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


    /**
     * 删除指定的Item
     *
     * @param position
     */
    public void removeData(int position) {
        sampleData.remove(position);
        //  通知RecyclerView控件某个Item已经被删除
        notifyItemRemoved(position);

    }


    /**
     * 在指定位置加入一个新的Item
     *
     * @param positionToAdd
     */
    public void addItem(int positionToAdd) {
        sampleData.add(positionToAdd, new SampleModel("新的列表项" + new Random().nextInt(10000)));
        //  通知RecyclerView控件插入了某个Item
        notifyItemInserted(positionToAdd);
    }


    /**
     * 相应Item中的控件
     */
    public static class ViewHolder extends RecyclerView.ViewHolder {

        private final TextView textViewSample;

        public ViewHolder(View itemView) {
            super(itemView);
            textViewSample = (TextView) itemView
                    .findViewById(R.id.textViewSample);
        }
    }


}

方法二：使用观察者模式实现

原理：
为RecyclerView的每一个子item设置setOnClickListener。然后在onClick中再调用一次对外封装的接口。将这个事件传递给外面的调用者。而“为RecyclerView的每一个子item设置setOnClickListener”在Adapter中设置。事实上直接在onClick中也能全然处理item的点击事件，可是这样会破坏代码的逻辑。

步骤
在自己定义的adapter（记得implements View.OnClickListener，以下有个onClick方法）中定义例如以下接口,模拟ListView的OnItemClickListener：

 //define interface
 public static interface OnRecyclerViewItemClickListener {
        void onItemClick(View view , String data);
    }

声明一个这个接口的变量：

  private OnRecyclerViewItemClickListener mOnItemClickListener = null;

在onCreateViewHolder()中为每一个item加入点击事件：

 @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup,  int viewType) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.item, viewGroup, false);
        ViewHolder vh = new ViewHolder(view);
        //将创建的View注冊点击事件
        view.setOnClickListener(this);
        return vh;
    }

将点击事件转移给外面的调用者：

 @Override
    public void onClick(View v) {
        if (mOnItemClickListener != null) {
            //注意这里使用getTag方法获取数据
            mOnItemClickListener.onItemClick(v,(String)v.getTag());
        }
    }

意上面调用接口的onItemClick()中的v.getTag()方法，这须要在onBindViewHolder()方法中设置和item相关的数据

@Override
    public void onBindViewHolder(ViewHolder viewHolder,  int position) {
        viewHolder.mTextView.setText(datas[position]);
        //将数据保存在itemView的Tag中，以便点击时进行获取
        viewHolder.itemView.setTag(datas[position]);
    }

最后暴露给外面的调用者，定义一个设置Listener的方法（）：

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

以上全部步骤都发生在自己定义的adapter中，典型的观察者模式，有点绕的地方在于，这里涉及到两个观察者模式的使用，view的setOnClickListener本来就是观察者模式，我们将这个观察者模式的事件监听传递给了我们自己的观察者模式。

在Activity中使用

mRecyclerView = (RecyclerView)findViewById(R.id.my_recycler_view);
        //创建默认的线性LayoutManager
        mLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(mLayoutManager);
        //假设能够确定每一个item的高度是固定的，设置这个选项能够提高性能
        mRecyclerView.setHasFixedSize(true);
        //创建并设置Adapter
        mAdapter = new MyAdapter(data);
        mRecyclerView.setAdapter(mAdapter);
        mAdapter.setOnItemClickListener(new OnRecyclerViewItemClickListener(){
            @Override    
            public void onItemClick(View view , String data){
                Toast.makeText(MainActivity.this, data, 600).show();
            }
        });

~

RecyclerView加入Header

。。。。。。