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Android 自定义RecyclerView 实现真正的Gallery效果

2017-08-30 13:59 411 查看

转载请标明出处：http://blog.csdn.net/lmj623565791/article/details/38173061 ，本文出自：【张鸿洋的博客】

上一篇博客我使用自定义HorizontalScrollView写了一个具有HorizontalScrollView效果和ViewPager特性的横向图片轮播，详见：Android
自定义 HorizontalScrollView 打造再多图片（控件）也不怕 OOM 的横向滑动效果。其实制作横向滚动的不得不说另一个控件，就是Google官方最近新增加的RecyclerView，据说是ListView的升级版本，本篇博客，首先介绍RecyclerView的用法，然后经行一定的分析；最后自定义一下RecyclerView实现我们需要的相册效果。

1、RecyclerView的基本用法
首先主Activity的布局文件：

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<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/id_recyclerview_horizontal"
        android:layout_width="match_parent"
        android:layout_height="120dp"
        android:layout_centerVertical="true"
        android:background="#FF0000"
        android:scrollbars="none" />

</RelativeLayout>

<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/id_recyclerview_horizontal"
android:layout_width="match_parent"
android:layout_height="120dp"
android:layout_centerVertical="true"
android:background="#FF0000"
android:scrollbars="none" />

</RelativeLayout>

Item的布局文件：

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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="120dp"
    android:layout_height="120dp"
    android:background="@drawable/item_bg02" >

    <ImageView
        android:id="@+id/id_index_gallery_item_image"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_margin="5dp"
        android:scaleType="centerCrop" />

    <TextView
        android:id="@+id/id_index_gallery_item_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/id_index_gallery_item_image"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="5dp"
        android:layout_marginTop="5dp"
        android:textColor="#ff0000"
        android:text="some info"
        android:textSize="12dp" />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="120dp"
android:layout_height="120dp"
android:background="@drawable/item_bg02" >

<ImageView
android:id="@+id/id_index_gal
1a143
lery_item_image"
android:layout_width="80dp"
android:layout_height="80dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_margin="5dp"
android:scaleType="centerCrop" />

<TextView
android:id="@+id/id_index_gallery_item_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/id_index_gallery_item_image"
android:layout_centerHorizontal="true"
android:layout_marginBottom="5dp"
android:layout_marginTop="5dp"
android:textColor="#ff0000"
android:text="some info"
android:textSize="12dp" />

</RelativeLayout>

数据适配器：

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package com.example.zhy_horizontalscrollview03;

import java.util.List;

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.ImageView;
import android.widget.TextView;

public class GalleryAdapter extends
        RecyclerView.Adapter<GalleryAdapter.ViewHolder>
{

    private LayoutInflater mInflater;
    private List<Integer> mDatas;

    public GalleryAdapter(Context context, List<Integer> datats)
    {
        mInflater = LayoutInflater.from(context);
        mDatas = datats;
    }

    public static class ViewHolder extends RecyclerView.ViewHolder
    {
        public ViewHolder(View arg0)
        {
            super(arg0);
        }

        ImageView mImg;
        TextView mTxt;
    }

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

    /**
     * 创建ViewHolder
     */
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i)
    {
        View view = mInflater.inflate(R.layout.activity_index_gallery_item,
                viewGroup, false);
        ViewHolder viewHolder = new ViewHolder(view);

        viewHolder.mImg = (ImageView) view
                .findViewById(R.id.id_index_gallery_item_image);
        return viewHolder;
    }

    /**
     * 设置值
     */
    @Override
    public void onBindViewHolder(final ViewHolder viewHolder, final int i)
    {
        viewHolder.mImg.setImageResource(mDatas.get(i));
    }

}

package com.example.zhy_horizontalscrollview03;

import java.util.List;

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.ImageView;
import android.widget.TextView;

public class GalleryAdapter extends
RecyclerView.Adapter<GalleryAdapter.ViewHolder>
{

private LayoutInflater mInflater;
private List<Integer> mDatas;

public GalleryAdapter(Context context, List<Integer> datats)
{
mInflater = LayoutInflater.from(context);
mDatas = datats;
}

public static class ViewHolder extends RecyclerView.ViewHolder
{
public ViewHolder(View arg0)
{
super(arg0);
}

ImageView mImg;
TextView mTxt;
}

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

/**
* 创建ViewHolder
*/
@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i)
{
View view = mInflater.inflate(R.layout.activity_index_gallery_item,
viewGroup, false);
ViewHolder viewHolder = new ViewHolder(view);

viewHolder.mImg = (ImageView) view
.findViewById(R.id.id_index_gallery_item_image);
return viewHolder;
}

/**
* 设置值
*/
@Override
public void onBindViewHolder(final ViewHolder viewHolder, final int i)
{
viewHolder.mImg.setImageResource(mDatas.get(i));
}

}

可以看到数据适配器与BaseAdapter比较发生了相当大的变化，主要有3个方法：

getItemCount 这个不用说，获取总的条目数

onCreateViewHolder 创建ViewHolder

onBindViewHolder 将数据绑定至ViewHolder

可见，RecyclerView对ViewHolder也进行了一定的封装，但是如果你仔细观察，你会发出一个疑问，ListView里面有个getView返回View为Item的布局，那么这个Item的样子在哪控制？

其实是这样的，我们创建的ViewHolder必须继承RecyclerView.ViewHolder，这个RecyclerView.ViewHolder的构造时必须传入一个View，这个View相当于我们ListView getView中的convertView （即：我们需要inflate的item布局需要传入）。

还有一点，ListView中convertView是复用的，在RecyclerView中，是把ViewHolder作为缓存的单位了，然后convertView作为ViewHolder的成员变量保持在ViewHolder中，也就是说，假设没有屏幕显示10个条目，则会创建10个ViewHolder缓存起来，每次复用的是ViewHolder，所以他把getView这个方法变为了onCreateViewHolder。有兴趣的自己打印下Log，测试下。

最后在Activity中使用：

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package com.example.zhy_horizontalscrollview03;

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

import android.app.Activity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.Window;

public class MainActivity extends Activity
{

    private RecyclerView mRecyclerView;
    private GalleryAdapter mAdapter;
    private List<Integer> mDatas;


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

        initDatas();
        //得到控件
        mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview_horizontal);
        //设置布局管理器
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        mRecyclerView.setLayoutManager(linearLayoutManager);
        //设置适配器
        mAdapter = new GalleryAdapter(this, mDatas);
        mRecyclerView.setAdapter(mAdapter);


    }


    private void initDatas()
    {
        mDatas = new ArrayList<Integer>(Arrays.asList(R.drawable.a,
                R.drawable.b, R.drawable.c, R.drawable.d, R.drawable.e,
                R.drawable.f, R.drawable.g, R.drawable.h, R.drawable.l));
    }

}

package com.example.zhy_horizontalscrollview03;

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

import android.app.Activity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.Window;

public class MainActivity extends Activity
{

private RecyclerView mRecyclerView;
private GalleryAdapter mAdapter;
private List<Integer> mDatas;

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

initDatas();
//得到控件
mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview_horizontal);
//设置布局管理器
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
mRecyclerView.setLayoutManager(linearLayoutManager);
//设置适配器
mAdapter = new GalleryAdapter(this, mDatas);
mRecyclerView.setAdapter(mAdapter);

}

private void initDatas()
{
mDatas = new ArrayList<Integer>(Arrays.asList(R.drawable.a,
R.drawable.b, R.drawable.c, R.drawable.d, R.drawable.e,
R.drawable.f, R.drawable.g, R.drawable.h, R.drawable.l));
}

}

使用起来也很方便，唯一的区别就是要设置LayoutManager，目前只有一个实现类，就是LinearLayoutManager，可以设置为水平或者垂直。

最后效果图：

效果很不错，这就是RecyclerView的基本用法了，但是你会发现一个坑爹的地方，竟然没有提供setOnItemClickListener这个回调，要不要这么坑爹。。。

2、为RecyclerView添加OnItemClickListener回调
虽然它没有提供，但是添加个OnItemClickListener对我们来说还不是小菜一碟~

我决定在Adapter中添加这个回调接口：

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package com.example.zhy_horizontalscrollview03;

import java.util.List;

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

public class GalleryAdapter extends
        RecyclerView.Adapter<GalleryAdapter.ViewHolder>
{

    /**
     * ItemClick的回调接口
     * @author zhy
     *
     */
    public interface OnItemClickLitener
    {
        void onItemClick(View view, int position);
    }

    private OnItemClickLitener mOnItemClickLitener;

    public void setOnItemClickLitener(OnItemClickLitener mOnItemClickLitener)
    {
        this.mOnItemClickLitener = mOnItemClickLitener;
    }

    private LayoutInflater mInflater;
    private List<Integer> mDatas;

    public GalleryAdapter(Context context, List<Integer> datats)
    {
        mInflater = LayoutInflater.from(context);
        mDatas = datats;
    }

    public static class ViewHolder extends RecyclerView.ViewHolder
    {
        public ViewHolder(View arg0)
        {
            super(arg0);
        }

        ImageView mImg;
        TextView mTxt;
    }

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

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i)
    {
        View view = mInflater.inflate(R.layout.activity_index_gallery_item,
                viewGroup, false);
        ViewHolder viewHolder = new ViewHolder(view);

        viewHolder.mImg = (ImageView) view
                .findViewById(R.id.id_index_gallery_item_image);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(final ViewHolder viewHolder, final int i)
    {
        viewHolder.mImg.setImageResource(mDatas.get(i));

        //如果设置了回调，则设置点击事件
        if (mOnItemClickLitener != null)
        {
            viewHolder.itemView.setOnClickListener(new OnClickListener()
            {
                @Override
                public void onClick(View v)
                {
                    mOnItemClickLitener.onItemClick(viewHolder.itemView, i);
                }
            });

        }

    }

}

package com.example.zhy_horizontalscrollview03;

import java.util.List;

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

public class GalleryAdapter extends
RecyclerView.Adapter<GalleryAdapter.ViewHolder>
{

/**
* ItemClick的回调接口
* @author zhy
*
*/
public interface OnItemClickLitener
{
void onItemClick(View view, int position);
}

private OnItemClickLitener mOnItemClickLitener;

public void setOnItemClickLitener(OnItemClickLitener mOnItemClickLitener)
{
this.mOnItemClickLitener = mOnItemClickLitener;
}

private LayoutInflater mInflater;
private List<Integer> mDatas;

public GalleryAdapter(Context context, List<Integer> datats)
{
mInflater = LayoutInflater.from(context);
mDatas = datats;
}

public static class ViewHolder extends RecyclerView.ViewHolder
{
public ViewHolder(View arg0)
{
super(arg0);
}

ImageView mImg;
TextView mTxt;
}

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

@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i)
{
View view = mInflater.inflate(R.layout.activity_index_gallery_item,
viewGroup, false);
ViewHolder viewHolder = new ViewHolder(view);

viewHolder.mImg = (ImageView) view
.findViewById(R.id.id_index_gallery_item_image);
return viewHolder;
}

@Override
public void onBindViewHolder(final ViewHolder viewHolder, final int i)
{
viewHolder.mImg.setImageResource(mDatas.get(i));

//如果设置了回调，则设置点击事件
if (mOnItemClickLitener != null)
{
viewHolder.itemView.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
mOnItemClickLitener.onItemClick(viewHolder.itemView, i);
}
});

}

}

}

很简单，创建一个接口，提供一个设置入口，然后在onBindViewHolder中判断即可。

最后在主Activity中设置监听：

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mAdapter = new GalleryAdapter(this, mDatas);
mAdapter.setOnItemClickLitener(new OnItemClickLitener()
{
    @Override
    public void onItemClick(View view, int position)
    {
        Toast.makeText(MainActivity.this, position+"", Toast.LENGTH_SHORT)
                .show();
    }
});
mRecyclerView.setAdapter(mAdapter);

mAdapter = new GalleryAdapter(this, mDatas);
mAdapter.setOnItemClickLitener(new OnItemClickLitener()
{
@Override
public void onItemClick(View view, int position)
{
Toast.makeText(MainActivity.this, position+"", Toast.LENGTH_SHORT)
.show();
}
});
mRecyclerView.setAdapter(mAdapter);

好了，这样就行了，看效果图：

效果还是不错的，接下来我想改成相册效果，即上面显示一张大图，下面的RecyclerView做为图片切换的指示器。

3、自定义RecyclerView实现滚动时内容联动
首先修改下布局：

布局文件：

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<LinearLayout 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:orientation="vertical" >

    <FrameLayout
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1" >

        <ImageView
            android:id="@+id/id_content"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_gravity="center"
            android:layout_margin="10dp"
            android:scaleType="centerCrop"
            android:src="@drawable/ic_launcher" />
    </FrameLayout>

    <com.example.zhy_horizontalscrollview03.MyRecyclerView
        android:id="@+id/id_recyclerview_horizontal"
        android:layout_width="match_parent"
        android:layout_height="120dp"
        android:layout_gravity="bottom"
        android:background="#FF0000"
        android:scrollbars="none" />

</LinearLayout>

<LinearLayout 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:orientation="vertical" >

<FrameLayout
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1" >

<ImageView
android:id="@+id/id_content"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="center"
android:layout_margin="10dp"
android:scaleType="centerCrop"
android:src="@drawable/ic_launcher" />
</FrameLayout>

<com.example.zhy_horizontalscrollview03.MyRecyclerView
android:id="@+id/id_recyclerview_horizontal"
android:layout_width="match_parent"
android:layout_height="120dp"
android:layout_gravity="bottom"
android:background="#FF0000"
android:scrollbars="none" />

</LinearLayout>

添加一个显示大图的区域，把RecyclerView改为自己定义的。

然后看我们自定义RecyclerView的代码：

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package com.example.zhy_horizontalscrollview03;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class CopyOfMyRecyclerView extends RecyclerView
{

    public CopyOfMyRecyclerView(Context context, AttributeSet attrs)
    {
        super(context, attrs);
    }

    private View mCurrentView;

    /**
     * 滚动时回调的接口
     */
    private OnItemScrollChangeListener mItemScrollChangeListener;

    public void setOnItemScrollChangeListener(
            OnItemScrollChangeListener mItemScrollChangeListener)
    {
        this.mItemScrollChangeListener = mItemScrollChangeListener;
    }

    public interface OnItemScrollChangeListener
    {
        void onChange(View view, int position);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b)
    {
        super.onLayout(changed, l, t, r, b);

        mCurrentView = getChildAt(0);

        if (mItemScrollChangeListener != null)
        {
            mItemScrollChangeListener.onChange(mCurrentView,
                    getChildPosition(mCurrentView));
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent e)
    {

        if (e.getAction() == MotionEvent.ACTION_MOVE)
        {
            mCurrentView = getChildAt(0);
            // Log.e("TAG", getChildPosition(getChildAt(0)) + "");
            if (mItemScrollChangeListener != null)
            {
                mItemScrollChangeListener.onChange(mCurrentView,
                        getChildPosition(mCurrentView));

            }

        }

        return super.onTouchEvent(e);
    }

}

package com.example.zhy_horizontalscrollview03;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class CopyOfMyRecyclerView extends RecyclerView
{

public CopyOfMyRecyclerView(Context context, AttributeSet attrs)
{
super(context, attrs);
}

private View mCurrentView;

/**
* 滚动时回调的接口
*/
private OnItemScrollChangeListener mItemScrollChangeListener;

public void setOnItemScrollChangeListener(
OnItemScrollChangeListener mItemScrollChangeListener)
{
this.mItemScrollChangeListener = mItemScrollChangeListener;
}

public interface OnItemScrollChangeListener
{
void onChange(View view, int position);
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b)
{
super.onLayout(changed, l, t, r, b);

mCurrentView = getChildAt(0);

if (mItemScrollChangeListener != null)
{
mItemScrollChangeListener.onChange(mCurrentView,
getChildPosition(mCurrentView));
}
}

@Override
public boolean onTouchEvent(MotionEvent e)
{

if (e.getAction() == MotionEvent.ACTION_MOVE)
{
mCurrentView = getChildAt(0);
// Log.e("TAG", getChildPosition(getChildAt(0)) + "");
if (mItemScrollChangeListener != null)
{
mItemScrollChangeListener.onChange(mCurrentView,
getChildPosition(mCurrentView));

}

}

return super.onTouchEvent(e);
}

}

定义了一个滚动时回调的接口，然后在onTouchEvent中，监听ACTION_MOVE，用户手指滑动时，不断把当前第一个View回调回去~

关于我咋知道getChildAt(0)和getChildPosition()可用，起初我以为有getFirstVisibleItem这个方法，后来发现么有；但是发现了getRecycledViewPool()看名字我觉得是Viewholder那个缓存队列，我想那么直接取这个队列的第一个不就是我要的View么，后来没有成功。我就观察它内部的View，最后发现，第一个显示的始终是它第一个child，至于getChildPosition这个看方法就看出来了。

现在的效果：

和我之前那个例子的效果是一模一样的，不过，我还想做一些改变，我觉得Gallery或者说相册的指示器，下面可能1000来张图片，我不仅喜欢手指在屏幕上滑动时，图片会自动切换。我还希望，如果我给指示器一个加速度，即使手指离开，下面还在滑动，上面也会联动。而且我还想做些优化，直接在ACTION_MOVE中回调，触发的频率太高了，理论上一张图片只会触发一次~~

4、优化与打造真正的Gallery效果
既然希望手指离开还能联动，那么不仅需要ACTION_MOVE需要监听，还得监听一个加速度，速度到达一定值，然后继续移动~~再理一理，需要这么麻烦么，不是能滚动么，那么应该有OnScrollListener啊，小看一把，果然有，哈哈哈~天助我也，下面看修改后的代码：

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package com.example.zhy_horizontalscrollview03;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.RecyclerView.OnScrollListener;
import android.util.AttributeSet;
import android.view.View;

public class MyRecyclerView extends RecyclerView implements OnScrollListener
{

    /**
     * 记录当前第一个View
     */
    private View mCurrentView;

    private OnItemScrollChangeListener mItemScrollChangeListener;

    public void setOnItemScrollChangeListener(
            OnItemScrollChangeListener mItemScrollChangeListener)
    {
        this.mItemScrollChangeListener = mItemScrollChangeListener;
    }

    public interface OnItemScrollChangeListener
    {
        void onChange(View view, int position);
    }

    public MyRecyclerView(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        this.setOnScrollListener(this);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b)
    {
        super.onLayout(changed, l, t, r, b);

        mCurrentView = getChildAt(0);

        if (mItemScrollChangeListener != null)
        {
            mItemScrollChangeListener.onChange(mCurrentView,
                    getChildPosition(mCurrentView));
        }
    }


    @Override
    public void onScrollStateChanged(int arg0)
    {
    }

    /**
     *
     * 滚动时，判断当前第一个View是否发生变化，发生才回调
     */
    @Override
    public void onScrolled(int arg0, int arg1)
    {
        View newView = getChildAt(0);

        if (mItemScrollChangeListener != null)
        {
            if (newView != null && newView != mCurrentView)
            {
                mCurrentView = newView ;
                mItemScrollChangeListener.onChange(mCurrentView,
                        getChildPosition(mCurrentView));

            }
        }

    }

}

package com.example.zhy_horizontalscrollview03;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.RecyclerView.OnScrollListener;
import android.util.AttributeSet;
import android.view.View;

public class MyRecyclerView extends RecyclerView implements OnScrollListener
{

/**
* 记录当前第一个View
*/
private View mCurrentView;

private OnItemScrollChangeListener mItemScrollChangeListener;

public void setOnItemScrollChangeListener(
OnItemScrollChangeListener mItemScrollChangeListener)
{
this.mItemScrollChangeListener = mItemScrollChangeListener;
}

public interface OnItemScrollChangeListener
{
void onChange(View view, int position);
}

public MyRecyclerView(Context context, AttributeSet attrs)
{
super(context, attrs);
// TODO Auto-generated constructor stub
this.setOnScrollListener(this);
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b)
{
super.onLayout(changed, l, t, r, b);

mCurrentView = getChildAt(0);

if (mItemScrollChangeListener != null)
{
mItemScrollChangeListener.onChange(mCurrentView,
getChildPosition(mCurrentView));
}
}

@Override
public void onScrollStateChanged(int arg0)
{
}

/**
*
* 滚动时，判断当前第一个View是否发生变化，发生才回调
*/
@Override
public void onScrolled(int arg0, int arg1)
{
View newView = getChildAt(0);

if (mItemScrollChangeListener != null)
{
if (newView != null && newView != mCurrentView)
{
mCurrentView = newView ;
mItemScrollChangeListener.onChange(mCurrentView,
getChildPosition(mCurrentView));

}
}

}

}

我放弃了重写onTouchEvent方法，而是让这个类实现RecyclerView.OnScrollListener接口，然后设置监听，在onScrolled里面进行判断。

至于优化：我使用了一个成员变化存储当前第一个View，只有第一个View发生变化时才回调~~太完美了~

看MainActivity:

[java]
view plain
copy

print ?

package com.example.zhy_horizontalscrollview03;

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

import android.app.Activity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.Window;
import android.widget.ImageView;
import android.widget.Toast;

import com.example.zhy_horizontalscrollview03.GalleryAdapter.OnItemClickLitener;
import com.example.zhy_horizontalscrollview03.MyRecyclerView.OnItemScrollChangeListener;

public class MainActivity extends Activity
{

    private MyRecyclerView mRecyclerView;
    private GalleryAdapter mAdapter;
    private List<Integer> mDatas;
    private ImageView mImg ;


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

        mImg = (ImageView) findViewById(R.id.id_content);

        mDatas = new ArrayList<Integer>(Arrays.asList(R.drawable.a,
                R.drawable.b, R.drawable.c, R.drawable.d, R.drawable.e,
                R.drawable.f, R.drawable.g, R.drawable.h, R.drawable.l));

        mRecyclerView = (MyRecyclerView) findViewById(R.id.id_recyclerview_horizontal);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);

        mRecyclerView.setLayoutManager(linearLayoutManager);
        mAdapter = new GalleryAdapter(this, mDatas);
        mRecyclerView.setAdapter(mAdapter);

        mRecyclerView.setOnItemScrollChangeListener(new OnItemScrollChangeListener()
        {
            @Override
            public void onChange(View view, int position)
            {
                mImg.setImageResource(mDatas.get(position));
            };
        });

        mAdapter.setOnItemClickLitener(new OnItemClickLitener()
        {
            @Override
            public void onItemClick(View view, int position)
            {
//              Toast.makeText(getApplicationContext(), position + "", Toast.LENGTH_SHORT)
//                      .show();
                mImg.setImageResource(mDatas.get(position));
            }
        });

    }

}

package com.example.zhy_horizontalscrollview03;

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

import android.app.Activity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.Window;
import android.widget.ImageView;
import android.widget.Toast;

import com.example.zhy_horizontalscrollview03.GalleryAdapter.OnItemClickLitener;
import com.example.zhy_horizontalscrollview03.MyRecyclerView.OnItemScrollChangeListener;

public class MainActivity extends Activity
{

private MyRecyclerView mRecyclerView;
private GalleryAdapter mAdapter;
private List<Integer> mDatas;
private ImageView mImg ;

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

mImg = (ImageView) findViewById(R.id.id_content);

mDatas = new ArrayList<Integer>(Arrays.asList(R.drawable.a,
R.drawable.b, R.drawable.c, R.drawable.d, R.drawable.e,
R.drawable.f, R.drawable.g, R.drawable.h, R.drawable.l));

mRecyclerView = (MyRecyclerView) findViewById(R.id.id_recyclerview_horizontal);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);

mRecyclerView.setLayoutManager(linearLayoutManager);
mAdapter = new GalleryAdapter(this, mDatas);
mRecyclerView.setAdapter(mAdapter);

mRecyclerView.setOnItemScrollChangeListener(new OnItemScrollChangeListener()
{
@Override
public void onChange(View view, int position)
{
mImg.setImageResource(mDatas.get(position));
};
});

mAdapter.setOnItemClickLitener(new OnItemClickLitener()
{
@Override
public void onItemClick(View view, int position)
{
//				Toast.makeText(getApplicationContext(), position + "", Toast.LENGTH_SHORT)
//						.show();
mImg.setImageResource(mDatas.get(position));
}
});

}

}

代码没什么变化~多了个设置回调~

效果图：

可以看到不仅支持手机在上面移动时的变化，如果我给了一个加速度，下面持续滚动，上面也会持续变化~~大赞~每张图片回调一次，效率也相当不错。

好了，看完这边博客，相信大家对于RecyclerView有了一定的认识，甚至对于如何改造一个控件也多了一份了解~~

如果觉得不错，就留个言或者点个赞，表示对我的支持

源码点击下载

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