Android5.x RecyclerView 应用解析

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1.导入v7包

要想使用RecyclerView，我们首先要导入support-v7包，因为我用的是android studio所以我们需要在build.gradle加入如下代码用来自动导入support-v7包，记得配置完后重新Build一下工程。

dependencies {
    compile fileTree(include: '*.jar', dir: 'libs')
    compile 'com.android.support:appcompat-v7:22.2.0'
    compile 'com.android.support:design:22.2.0'
    compile 'com.android.support:recyclerview-v7:22.1.0'
}

2. 使用RecyclerView

和ListView的写法大概一样：

RecyclerView mRecyclerView= (RecyclerView) this.findViewById(R.id.id_recyclerview);
//设置布局管理器
       mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
       // 设置item增加和删除时的动画
       mRecyclerView.setItemAnimator(new DefaultItemAnimator());
       mHomeAdaper=new HomeAdapter(this, mList);
       mRecyclerView.setAdapter(mHomeAdaper);

要比listview的设置要复杂一些，主要是需要自己去自定义分割线，设置动画和布局管理器等等。
布局文件activity_recycler_view.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.support.v7.widget.RecyclerView
    android:id="@+id/id_recyclerview"
    android:divider="#FFB900"
    android:dividerHeight="1dp"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

</RelativeLayout>

让我们来看看变化最大的Adaper:

class HomeAdapter extends RecyclerView.Adapter<HomeAdapter.MyViewHolder>
{
    private List<String> mList;
    private Context mContext;;
    public HomeAdapter(Context mContext,List<String>mList){
        this.mContext=mContext;
        this.mList=mList;
    }
    public void removeData(int position) {
        mList.remove(position);
        notifyItemRemoved(position);
    }
    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
    {
        MyViewHolder holder = new MyViewHolder(LayoutInflater.from(
                mContext).inflate(R.layout.item_recycler, parent,
                false));
        return holder;
    }
    @Override
    public void onBindViewHolder(final MyViewHolder holder, final int position)
    {
        holder.tv.setText(mList.get(position));
    }
    @Override
    public int getItemCount()
    {
        return mList.size();
    }
    class MyViewHolder extends RecyclerView.ViewHolder
    {
        TextView tv;
        public MyViewHolder(View view)
        {
            super(view);
            tv = (TextView) view.findViewById(R.id.tv_item);
        }
    }
}

最大的改进就是对ViewHolder进行了封装定义，不用自己去自定义了，另外Adaper继承RecyclerView.Adapter，在onCreateViewHolder加载条目布局，在onBindViewHolder中将视图与数据进行绑定。

布局文件item_recycler.xml：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:background="@android:color/white"
    android:layout_height="wrap_content"
    >

    <TextView
        android:id="@+id/tv_item"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"
        android:text="moon" />
</FrameLayout>

来看看效果：

没有分割线，难看的很，下面我们来讲一讲分割线。

3.设置分割线 ItemDecoration

用mRecyclerView.addItemDecoration()来加入分割线，谷歌没有提供默认的分割线需要我们继承RecyclerView.ItemDecoration来自定义分割线：

public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    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) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();
        setOrientation(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);
            android.support.v7.widget.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);
        }
    }
}

实现了自定义的分割线，我们只要在setAdapter之前加入如下代码便可加入分割线：

mRecyclerView.addItemDecoration(new DividerItemDecoration(RecyclerViewActivity.this, DividerItemDecoration.VERTICAL_LIST));

4. 自定义点击事件

列表中条目的点击事件需要我们自己来定义，这是一个不尽如人意的地方，但是自定义点击事件的话也并不是很难，在adaper中定义接口并提供回调：

 public interface OnItemClickListener
    {
        void onItemClick(View view, int position);
        void onItemLongClick(View view,int position);

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

接下来对item中的控件进行点击事件监听并回调给我们自定义的监听：

@Override
   public void onBindViewHolder(final MyViewHolder holder, final int position)
   {
       holder.tv.setText(mList.get(position));
       if (mOnItemClickListener != null)
       {
           holder.tv.setOnClickListener(new View.OnClickListener()
           {
               @Override
               public void onClick(View v)
               {
                   int pos = holder.getLayoutPosition();
                   mOnItemClickListener.onItemClick(holder.tv,pos);
               }
           });
           holder.tv.setOnLongClickListener(new View.OnLongClickListener() {
               @Override
               public boolean onLongClick(View view) {
                   int pos = holder.getLayoutPosition();
                   mOnItemClickListener.onItemLongClick(holder.tv,pos);
                   return false;
               }
           });
       }
   }

在Activity进行监听：

mHomeAdaper.setOnItemClickListener(new HomeAdapter.OnItemClickListener() {
           @Override
           public void onItemClick(View view, int position) {
               Toast.makeText(RecyclerViewActivity.this,"点击第"+(position+1)+"条",Toast.LENGTH_SHORT).show();
           }
           @Override
           public void onItemLongClick(View view, final int position) {
               new AlertDialog.Builder(RecyclerViewActivity.this)
                       .setTitle("确认删除嘛")
                       .setNegativeButton("取消",null)
                       .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                           @Override
                           public void onClick(DialogInterface dialogInterface, int i) {
                               mHomeAdaper.removeData(position);
                           }
                       })
                       .show();
           }
       });

长按时会弹出对话框，删除时会有消失的动画：

5. 实现GridView

只需要自定义横向的分割线然后在代码中设置：

mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(4,
               StaggeredGridLayoutManager.VERTICAL));
                mRecyclerView.addItemDecoration(new DividerGridItemDecoration(this));
                           

具体的代码会在下面给的源码中可以看见，实现效果：

6. 实现瀑布流

虽然第三方实现的瀑布流已经很不错了，但是谷歌这次提供的RecyclerView支持瀑布流我们没有理由不去用，因为更稳定，效率更高，自定义能力更强。
我们可以不用写
mRecyclerView.addItemDecoration(new DividerGridItemDecoration(this));
来设置分割线，可以在item布局文件中定义分割距离 android:layout_margin=”2dp”：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:background="@android:color/white"
    android:layout_height="wrap_content"
    android:layout_margin="2dp"
    >

    <TextView
        android:id="@+id/tv_item"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"
        android:text="moon" />
</FrameLayout>

实现瀑布流很简单只要在adaper写一个随机的高度来控制每个item的高度就可以了，通常这个高度是由服务端返回的数据高度来控制的，在这里我们写一个随机的高度来控制每个item的高度：

mHeights = new ArrayList<Integer>();
		for (int i = 0; i < mDatas.size(); i++)
		{
			mHeights.add( (int) (100 + Math.random() * 300));
		}

接着我们在adaper的onBindViewHolder来设置每个item的高度：

LayoutParams lp = holder.tv.getLayoutParams();
		lp.height = mHeights.get(position);
		holder.tv.setLayoutParams(lp);

具体的代码请看下面给的demo,来看看效果：

7. 源码说明

在RecyclerViewActivity的initView来配置你想要的效果：

 private void initView() {
        mRecyclerView= (RecyclerView) this.findViewById(R.id.id_recyclerview);
        //设置GridView
//        setGridView();
        //设置ListView
//        setListView();
         //设置瀑布流
        setWaterfallView();

    }

源码下载