RecyclerView中item点击事件

自从Google推出RecyclerView后，它就成为"宠儿"，自定义插件式的组件用起来很爽。但是很遗憾的是，Google并没有给我们提供item的点击事件函数，但是我们可以类似ListView的item点击事件来构造出我们自己的RecyclerView item的点击事件。首先我们看ListView如何用setOnItemClickListener()方法实现item的点击事件的呢，搞明白这个问题，我们还得去看ListView源码,打开源码发现，查找该方法，竟然查不到，是不是它父类AbsListView中的函数呢，其实也不是的。原来setOnItemClickListener()是AdapterView类中的方法，终于理清楚了关系：

ListView extends AbsListView     abstract class AbsListView extends AdapterView<ListAdapter> implements XXXXX              abstract class AdapterView<T extends Adapter> extends ViewGroup                   abstract class ViewGroup extends View implements ViewParent, ViewManager

上面简单给出了ListView类"祖宗"几代的关系图，原来ListView就是个View,哈哈，废话不多说了，感兴趣的朋友可以自己看源码。

那么我们瞧瞧setOnItemClickListener()是如何实现的呢？

public interface OnItemClickListener {    /**     * Callback method to be invoked when an item in this AdapterView has     * been clicked.     * <p>     * Implementers can call getItemAtPosition(position) if they need     * to access the data associated with the selected item.     *     * @param parent The AdapterView where the click happened.     * @param view The view within the AdapterView that was clicked (this     *            will be a view provided by the adapter)     * @param position The position of the view in the adapter.     * @param id The row id of the item that was clicked.     */    void onItemClick(AdapterView<?> parent, View view, int position, long id);}/** * Register a callback to be invoked when an item in this AdapterView has * been clicked. * * @param listener The callback that will be invoked. */public void setOnItemClickListener(@Nullable OnItemClickListener listener) {    mOnItemClickListener = listener;}

从上的源码中，可以找到，用到的是接口回调来完成的。上面的注释说明的太清楚了，不忍心删除因为我没有注释说的好。

下面给出ListView对象变量如何实现item点击事件的：

 listView.setOnItemClickListener(new OnItemClickListener() {        public void onItemClick(AdapterView<?> arg0,View view,final int index,long arg3){
                    /*
                     *调用者具体的实现逻辑
                     */
     }

  });

 原来就是这样实现的啊！现在是不是很明白了呢？

 说了那么多，接下来我们实战吧！

 在开始之前，看下最终demo实现的效果：

上面每一个item都是一个卡片状，而且点击的时候还有水波纹效果，实现上面的效果用到CardView,下面也会简单的介绍CardView使用。

我们item布局文件list_text.xml：(主要就是显示文本,布局比较简单)

<android.support.v7.widget.CardView       xmlns:card_view="http://schemas.android.com/apk/res-auto"          android:id="@+id/card_view"          android:layout_width="match_parent"          android:layout_height="match_parent"          card_view:cardBackgroundColor="@color/pink"          android:layout_marginLeft="@dimen/activity_horizontal_margin"          android:layout_marginRight="@dimen/activity_horizontal_margin"          android:layout_marginTop="5dp"          android:layout_marginBottom="15dp"          card_view:cardCornerRadius="10dp"          card_view:cardElevation="10dp"         android:foreground="@drawable/rippler"        xmlns:android="http://schemas.android.com/apk/res/android">    <TextView             android:id="@+id/text"      android:layout_width="match_parent"      android:gravity="center"      android:textSize="50sp"      android:layout_height="wrap_content"         />   </android.support.v7.widget.CardView>
主布局文件activity_main.xml:

<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.support.v7.widget.RecyclerView        android:id="@+id/recycler_view"        android:layout_width="match_parent"        android:layout_height="match_parent"/></RelativeLayout>
下面就是编写代码了，为了方便，全部放在一个类中了：

public class MainActivity extends Activity {     private ArrayList<String> array = new ArrayList<String>();private RecyclerView recycler;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initdata();recycler = (RecyclerView)findViewById(R.id.recycler_view);LinearLayoutManager layout = new LinearLayoutManager(this);recycler.setLayoutManager(layout);MyAdapter adapter = new MyAdapter();recycler.setAdapter(adapter);
<span style="font-size: 11.3pt;">                 </span><span style="font-family: Consolas; font-size: 11.3pt;">adapter.setOnItemClickListener(new onRecyclerViewItemClickListener(){</span>
            @Override                public void onItemClick(View view,String data){                Toast.makeText(MainActivity.this,"你好,我是"+data, Toast.LENGTH_SHORT).show();            }});}   public void initdata(){for(char i='a';i<='z';i++){array.add(String.valueOf(i));System.out.print(i);}}public class  MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder>{         private onRecyclerViewItemClickListener itemClickListener = null;@Overridepublic int getItemCount() {// TODO 自动生成的方法存根return array.size();}public void onBindViewHolder(ViewHolder viewholder, int position) {  //为item布局中的控件设置数值// TODO 自动生成的方法存根viewholder.textview.setText(array.get(position));viewholder.itemView.setTag(viewholder.textview.getText());}@Overridepublic ViewHolder onCreateViewHolder(ViewGroup viewgroup, int position) {// TODO 自动生成的方法存根View view = LayoutInflater.from(viewgroup.getContext()).inflate(R.layout.list_text,viewgroup,false); //获取item的布局view.setOnClickListener(new OnClickListener() {   //为每一个item绑定监听@Overridepublic void onClick(View v) {// TODO 自动生成的方法存根if (itemClickListener != null)<span style="font-family: Consolas; font-size: 11.3pt;">              </span>
                              itemClickListener.onItemClick(v,(String)v.getTag());                   }}});return new ViewHolder(view);    }   public  class ViewHolder extends RecyclerView.ViewHolder{  //获取item中的控件            private   TextView textview;public ViewHolder(View itemView) {super(itemView);// TODO 自动生成的构造函数存根textview = (TextView)itemView.findViewById(R.id.text);}}public void setOnItemClickListener(onRecyclerViewItemClickListener listener) {         this.itemClickListener = listener;    //  Log.d("ddd", itemClickListener.toString());    } }public  interface onRecyclerViewItemClickListener {void onItemClick(View v, String tag);}}
看下上面的效果吧：

 
有朋友会问，怎么少了item之间的分隔条啊，对，下面我们就把分隔条画出来。说到这里感觉本篇介绍的有点多，不过后面也会陆续介绍。
public class Dividerlios extends RecyclerView.ItemDecoration{    private final static int ARRAS[] = {android.R.attr.listDivider};//使用系统提供的分隔条   当然也可以自己绘制    private Drawable drawDivider;    public Dividerlios(Context context){TypedArray a = context.obtainStyledAttributes(ARRAS);drawDivider = a.getDrawable(0);a.recycle();}public void onDrawOver(Canvas canvas,RecyclerView recyclerView){ //在canvas上画分隔条，要获得分隔条的坐标int left = recyclerView.getPaddingLeft();  int right = recyclerView.getWidth() - recyclerView.getPaddingRight();int childCount = recyclerView.getChildCount();for(int i=0;i<childCount;i++){  //绘制全部的分隔条   View child = recyclerView.getChildAt(i);    RecyclerView.LayoutParams parame = (RecyclerView.LayoutParams)child.getLayoutParams();        int top = child.getBottom() + parame.bottomMargin;    int bottom = top + drawDivider.getIntrinsicHeight();    drawDivider.setBounds(left, top, right, bottom);    drawDivider.draw(canvas);}}} 
在MainActivity.java中添加：
Dividerlios divider= new Dividerlios(MainActivity.this);    recycler.addItemDecoration(divider);
然后上面的分割线效果就出来了。感兴趣朋友可以自己绘制分割线。

下面简单说明下，item里实现波纹和前景色变化，可以我们自定义drawable资源文件。
selecter.xml:
<selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_pressed="true">        <shape android:shape="rectangle">            <solid android:color="#18ffc400"/>        </shape>    </item>    <item android:state_focused="true"          android:state_enabled="true">        <shape android:shape="rectangle">        <solid android:color="#0f000000"/>        </shape>    </item>
rippler.xml:
<?xml version="1.0" encoding="utf-8"?><ripple xmlns:android="http://schemas.android.com/apk/res/android"         android:color="#20000000"        android:drawable="@drawable/<span style="font-family: Consolas; font-size: 15.0667px; white-space: pre;">selecter.xml</span>" />
关于上面drawable资源如何使用，后面的文章会说明。这里不再说明。

很久没更新博客，写博客主要为了巩固知识，如果能帮助到需要的朋友，我会非常开心。