public class MyDecoration extends ItemDecoration {
private static final int[] ATTRS = new int[]{
android.R.attr.listDivider
};
private Drawable mDivider;
public MyDecoration(Context ctx){
final TypedArray a = ctx.obtainStyledAttributes(ATTRS);
mDivider = a.getDrawable(0);
}
@Override
public void onDraw(Canvas c, RecyclerView parent, State state) {
int top = parent.getPaddingTop();
int bottom = parent.getHeight() - parent.getPaddingBottom();
int childCount = parent.getChildCount();
for(int i=0;i < childCount;i++){
View child = parent.getChildAt(i);
RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams)child.getLayoutParams();
int left = child.getRight() + layoutParams.rightMargin;
int right = left + mDivider.getIntrinsicWidth();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state) {
outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
}
}
Google提供了一个名为DefaultItemAnimator的默认ItemAnimator供开发者使用。如果开发者不为RecyclerView设置ItemAnimator，RecyclerView也会使用默认的DefaultItemAnimator。
显然，为了让动画效果起效，开发者必须通知Adapter数据有改变。之前我们使用Adapter时会调用notifyDataSetChanged()来通知Adapter数据改变并更新视图，现在RecyclerView,Adapter提供了许多notifyXyz()方法。
RecyclerView不再负责Item视图的布局及显示，所以RecyclerView也没有为Item开放OnItemClick等点击事件，这就需要开发者自己实现。
因为ViewHolder我们可以拿到每个Item的根布局，所以如果我们为根布局设置单独的OnClick监听并将其开放给Adapter，那不就可以在组装RecyclerView时就能够设置ItemClickListener，只不过这个Listener不是设置到RecyclerView上而是设置到Adapter。
public class MyViewHolder extends ViewHolder implements OnClickListener,OnLongClickListener{
public ImageView iv;
public TextView tv;
private MyItemClickListener mListener;
private MyItemLongClickListener mLongClickListener;
public MyViewHolder(View rootView,MyItemClickListener listener,MyItemLongClickListener longClickListener) {
super(rootView);
iv = (ImageView)rootView.findViewById(R.id.item_iv);
tv = (TextView)rootView.findViewById(R.id.item_tv);
this.mListener = listener;
this.mLongClickListener = longClickListener;
rootView.setOnClickListener(this);
rootView.setOnLongClickListener(this);
}
/**
* 点击监听
*/
@Override
public void onClick(View v) {
if(mListener != null){
mListener.onItemClick(v,getPosition());
}
}
/**
* 长按监听
*/
@Override
public boolean onLongClick(View arg0) {
if(mLongClickListener != null){
mLongClickListener.onItemLongClick(arg0, getPosition());
}
return true;
}
}
public class MyLayoutManager extends LinearLayoutManager {
public MyLayoutManager(Context context) {
super(context);
}
@Override
public void onMeasure(Recycler recycler, State state, int widthSpec,int heightSpec) {
View view = recycler.getViewForPosition(0);
if(view != null){
measureChild(view, widthSpec, heightSpec);
int measuredWidth = MeasureSpec.getSize(widthSpec);
int measuredHeight = view.getMeasuredHeight();
setMeasuredDimension(measuredWidth, measuredHeight);
}
}
}
