Android为RecyclerView添加item的点击事件

最终目的

模拟ListView的setOnItemClickListener()方法，调用者只须调用类似于setOnItemClickListener的东西就能获得被点击item的相关数据。

原理

为RecyclerView的每个子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的每个子item设置setOnClickListener”在Adapter中设置。其实直接在onClick中也能完全处理item的点击事件，但是这样会破坏代码的逻辑。

步骤

adapter中

自定义一个继承自RecyclerView.Adapter的MyAdapter。

1.在MyAdapter中定义如下接口,模拟ListView的OnItemClickListener：

    //define interface
       public static interface OnItemClickListener { 
           void onItemClick(View view , int position);
       }

声明一个这个接口的变量

    private OnItemClickListener mOnItemClickListener = null;

在onCreateViewHolder()中为每个item添加点击事件

    @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注册点击事件
           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position
               mOnItemClickListener.onItemClick(v,(int)v.getTag());
           }
       }

注意上面调用接口的onItemClick()中的v.getTag()方法，这需要在onBindViewHolder()方法中设置和item的position

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

以上所有步骤都发生在自定义的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);
           //如果可以确定每个item的高度是固定的，设置这个选项可以提高性能
           mRecyclerView.setHasFixedSize(true);
           //创建并设置Adapter
           mAdapter = new MyAdapter(data);
           mRecyclerView.setAdapter(mAdapter);
           mAdapter.setOnItemClickListener(new OnItemClickListener(){ 
               @Override    
               public void onItemClick(View view , int position){ 
                   Toast.makeText(MainActivity.this, data[position], 600).show();
               }
           });

完整代码

MyAdapter.java

package com.example.recyclerviewdemo;
   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;
   public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> implements View.OnClickListener{ 
       private  String[]  datas;
       public MyAdapter(String[] datas) { 
           this.datas = datas;
       }
       private OnItemClickListener mOnItemClickListener = null;
       //define interface
       public static interface OnItemClickListener { 
           void onItemClick(View view , int position);
       }
       @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注册点击事件
           view.setOnClickListener(this);
           return vh;
       }
       @Override
       public void onBindViewHolder(ViewHolder viewHolder,  int position) { 
           viewHolder.mTextView.setText(datas[position]);
           //将position保存在itemView的Tag中，以便点击时进行获取
           viewHolder.itemView.setTag(position);
       }
       @Override
       public void onClick(View v) { 
           if (mOnItemClickListener != null) { 
               //注意这里使用getTag方法获取position
               mOnItemClickListener.onItemClick(v,(int)v.getTag());
           }
       }
       public void setOnItemClickListener(OnItemClickListener listener) { 
           this.mOnItemClickListener = listener;
       }
       //获取数据的数量
       @Override
       public int getItemCount() { 
           return datas.length;
       }
       //自定义的ViewHolder，持有每个Item的的所有界面元素
       public static class ViewHolder extends RecyclerView.ViewHolder { 
           public TextView mTextView;
           public ViewHolder(View view){ 
           super(view);
               mTextView = (TextView) view.findViewById(R.id.text);
           }
       }
   }

item.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="50dip"
      >
       <TextView
           android:id="@+id/text"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           />
   </RelativeLayout>

MainActivity.java

package com.example.recyclerviewdemo;
   import com.example.recyclerviewdemo.MyAdapter.OnItemClickListener;
   import android.support.v7.app.ActionBarActivity;
   import android.support.v7.widget.LinearLayoutManager;
   import android.support.v7.widget.RecyclerView;
   import android.os.Bundle;
   import android.view.Menu;
   import android.view.MenuItem;
   import android.view.View;
   import android.widget.Toast;
   public class MainActivity extends ActionBarActivity { 
       private RecyclerView mRecyclerView;
       private LinearLayoutManager mLayoutManager;
       private MyAdapter mAdapter;
       private String[] data= new String[] { "aa","bb", "aa","bb", "aa","bb", "aa","bb", "aa","bb","aa","bb", "aa","bb", "aa","bb", "aa","bb", "aa","bb"  };
       @Override
       protected void onCreate(Bundle savedInstanceState) { 
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           mRecyclerView = (RecyclerView)findViewById(R.id.my_recycler_view);
           //创建默认的线性LayoutManager
           mLayoutManager = new LinearLayoutManager(this);
           mRecyclerView.setLayoutManager(mLayoutManager);
           //如果可以确定每个item的高度是固定的，设置这个选项可以提高性能
           mRecyclerView.setHasFixedSize(true);
           //创建并设置Adapter
           mAdapter = new MyAdapter(data);
           mRecyclerView.setAdapter(mAdapter);
           mAdapter.setOnItemClickListener(new OnItemClickListener(){ 
               @Override    
               public void onItemClick(View view , int position){ 
                   Toast.makeText(MainActivity.this, data[position], 600).show();
               }
           });
       }
       @Override
       public boolean onCreateOptionsMenu(Menu menu) { 
           // Inflate the menu; this adds items to the action bar if it is present.
           getMenuInflater().inflate(R.menu.main, menu);
           return true;
       }
       @Override
       public boolean onOptionsItemSelected(MenuItem item) { 
           // Handle action bar item clicks here. The action bar will
           // automatically handle clicks on the Home/Up button, so long
           // as you specify a parent activity in AndroidManifest.xml.
           int id = item.getItemId();
           if (id == R.id.action_settings) { 
               return true;
           }
           return super.onOptionsItemSelected(item);
       }
   }

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"
       tools:context=".MainActivity">
       <android.support.v7.widget.RecyclerView
           android:id="@+id/my_recycler_view"
           android:layout_width="match_parent"
           android:layout_height="match_parent"
           android:scrollbars="vertical"/>
   </RelativeLayout>

总结

在ListView中我们是调用ListView的setOnItemClickListener：

        mListView.setOnItemClickListener(new OnItemClickListener() { 
               public void onItemClick(AdapterView<?> parent, View v, int position, long id) { 
                       ...           
               }
           });

而在我们这里是调用mAdapter的setOnItemClickListener。