android.support.v7 包提供了一个新的组件：RecycleView，用以提供一个灵活的列表试图、显示大型数据集，它支持局部刷新、显示动画等功能，可以用来取代ListView与GridView.
然而在使用的过程中却遇到一些问题，基本现在手机页面都会有滑动到底部加载更多的功能，而RecycleView 并没有提供像ListView的addFooter等方法，所以实现起来还是有点麻烦。经过一段时间的摸索，终于找到实现RecycleView加载更多的方法。
本文主要通过RecycleView 的 ItemViewType 来实现RecycleView滑动到底部加载更多功能，支持 列表、网格、瀑布流等布局。
根据ItemViewType创建两种布局，一个用于显示正常内容的布局，一个用于加载布局，然后监听RecycleView的滚动事件，当滑动到底部时添加加载布局，对于列表布局来说很简单，不再熬述，然而对于网格布局与瀑布流布局来说，要解决"加载布局只占用一列"的问题,
1.对于网格布局，GridLayoutManager 提供了一个 setSpanSizeLookup() 的方法，用来设置每个条目可以占用的列数，默认为1.
2.对于瀑布流，StaggeredGridLayoutManager 提供了一个 StaggeredGridLayoutManager.LayoutParams 内部静态类，此类中有一个setFullSpan() 方法，用来设置条目跨越全列。
3.基类的实现方式如下：子类只需要重写以下方法：
onCreateNormalViewHolder(ViewGroup parent);
onBindNormalViewHolder(RecyclerView.ViewHolder holder, int position);
/**
* Created by sunwei on 2015/12/4.
* Email: lx_sunwei@163.com.
* Description: recycleView 滑动到底部加载更多
*/
public abstract class BaseLoadingAdapter<T> extends RecyclerView.Adapter<RecyclerView.ViewHolder> { private static final String TAG = "BaseLoadingAdapter"; //是否正在加载
public boolean mIsLoading = false;
//正常条目
private static final int TYPE_NORMAL_ITEM = 0;
//加载条目
private static final int TYPE_LOADING_ITEM = 1;
//加载viewHolder
private LoadingViewHolder mLoadingViewHolder;
//瀑布流
private StaggeredGridLayoutManager mStaggeredGridLayoutManager;
//数据集
private CircularArray<T> mTs;
//首次进入
private boolean mFirstEnter = true;
private RecyclerView mRecyclerView; public BaseLoadingAdapter(RecyclerView recyclerView, CircularArray<T> ts) { mTs = ts; mRecyclerView = recyclerView; setSpanCount(recyclerView); //notifyLoading();
} private OnLoadingListener mOnLoadingListener; /**
* 加载更多接口
*/
public interface OnLoadingListener {
void loading();
} /**
* 设置监听接口
*
* @param onLoadingListener onLoadingListener
*/
public void setOnLoadingListener(OnLoadingListener onLoadingListener) {
setScrollListener(mRecyclerView);
mOnLoadingListener = onLoadingListener;
} /**
* 加载完成
*/
public void setLoadingComplete() {
if (mTs.size() > 0 && mTs.getLast() == null) {
mIsLoading = false;
mTs.removeFromEnd(1);
notifyItemRemoved(mTs.size() - 1);
}
} /**
* 没有更多数据
*/
public void setLoadingNoMore() {
mIsLoading = false;
if (mLoadingViewHolder != null) {
mLoadingViewHolder.progressBar.setVisibility(View.GONE);
mLoadingViewHolder.tvLoading.setText("已加载完！");
}
} /**
* 加载失败
*/
public void setLoadingError() {
if (mLoadingViewHolder != null) {
mIsLoading = false;
mLoadingViewHolder.progressBar.setVisibility(View.GONE);
mLoadingViewHolder.tvLoading.setText("加载失败，点击重新加载！"); mLoadingViewHolder.tvLoading.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mOnLoadingListener != null) {
mIsLoading = true;
mLoadingViewHolder.progressBar.setVisibility(View.VISIBLE);
mLoadingViewHolder.tvLoading.setText("正在加载..."); mOnLoadingListener.loading();
}
}
});
}
} /**
* @return Whether it is possible for the child view of this layout to
* scroll up. Override this if the child view is a custom view.
*/
private boolean canScrollDown(RecyclerView recyclerView) {
return ViewCompat.canScrollVertically(recyclerView, 1);
} /**
* 设置加载item占据一行
*
* @param recyclerView recycleView
*/
private void setSpanCount(RecyclerView recyclerView) {
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager(); if (layoutManager == null) {
Log.e(TAG, "LayoutManager 为空,请先设置 recycleView.setLayoutManager(...)");
} //网格布局
if (layoutManager instanceof GridLayoutManager) {
final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {
int type = getItemViewType(position);
if (type == TYPE_NORMAL_ITEM) {
return 1;
} else {
return gridLayoutManager.getSpanCount();
}
}
});
} //瀑布流布局
if (layoutManager instanceof StaggeredGridLayoutManager) {
mStaggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
}
} /**
* 显示加载
*/
private void notifyLoading() {
if (mTs.size() != 0 && mTs.getLast() != null) {
mTs.addLast(null);
notifyItemInserted(mTs.size() - 1);
}
} /**
* 监听滚动事件
*
* @param recyclerView recycleView
*/
private void setScrollListener(RecyclerView recyclerView) {
if(recyclerView == null) {
Log.e(TAG, "recycleView 为空");
return;
} recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
} @Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy); if (!canScrollDown(recyclerView)) { //首次进入不加载
if (!mIsLoading && !mFirstEnter) { notifyLoading(); mIsLoading = true; if (mLoadingViewHolder != null) {
mLoadingViewHolder.progressBar.setVisibility(View.VISIBLE);
mLoadingViewHolder.tvLoading.setText("正在加载...");
} if (mOnLoadingListener != null) {
mOnLoadingListener.loading();
}
}
} if (mFirstEnter) {
mFirstEnter = false;
}
}
});
} /**
* 创建viewHolder
*
* @param parent viewGroup
* @return viewHolder
*/
public abstract RecyclerView.ViewHolder onCreateNormalViewHolder(ViewGroup parent); /**
* 绑定viewHolder
*
* @param holder viewHolder
* @param position position
*/
public abstract void onBindNormalViewHolder(RecyclerView.ViewHolder holder, int position); /**
* 加载布局
*/
private class LoadingViewHolder extends RecyclerView.ViewHolder {
public ProgressBar progressBar;
public TextView tvLoading;
public LinearLayout llyLoading; public LoadingViewHolder(View view) {
super(view); progressBar = (ProgressBar) view.findViewById(R.id.progress_loading);
tvLoading = (TextView) view.findViewById(R.id.tv_loading);
llyLoading = (LinearLayout) view.findViewById(R.id.lly_loading);
}
} @Override
public int getItemViewType(int position) {
T t = mTs.get(position);
if (t == null) {
return TYPE_LOADING_ITEM;
} else {
return TYPE_NORMAL_ITEM;
}
} @Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_NORMAL_ITEM) {
return onCreateNormalViewHolder(parent);
} else {
View view = LayoutInflater.from(parent.getContext()).inflate(
R.layout.loading_layout, parent, false);
mLoadingViewHolder = new LoadingViewHolder(view);
return mLoadingViewHolder;
}
} @Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
int type = getItemViewType(position);
if (type == TYPE_NORMAL_ITEM) {
onBindNormalViewHolder(holder, position);
} else { if (mStaggeredGridLayoutManager != null) {
StaggeredGridLayoutManager.LayoutParams layoutParams =
new StaggeredGridLayoutManager.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
layoutParams.setFullSpan(true); mLoadingViewHolder.llyLoading.setLayoutParams(layoutParams);
}
}
} @Override
public int getItemCount() {
return mTs.size();
}
}
Base Loading Adapter
4.一个简单的列子
/**
* Created by sunwei on 2015/12/4.
* Email: lx_sunwei@163.com.
* Description: 滑动到底部加载更多
*/
public class DesignLoaderMoreAdapter extends BaseLoadingAdapter<DesignItem> { private CircularArray<DesignItem> mDesignItems; public DesignLoaderMoreAdapter(RecyclerView recyclerView, CircularArray<DesignItem> datas) {
super(recyclerView, datas); mDesignItems = datas;
} //正常条目
public class DesignViewHolder extends RecyclerView.ViewHolder {
public TextView textView;
public CardView cardView;
public DesignViewHolder(View view) {
super(view);
textView = (TextView) view.findViewById(R.id.tv_design);
cardView = (CardView) view.findViewById(R.id.cardView_designer); }
} @Override
public RecyclerView.ViewHolder onCreateNormalViewHolder(ViewGroup parent) {
View view = LayoutInflater.from(parent.getContext()).inflate(
R.layout.list_item_design, parent, false);
return new DesignViewHolder(view);
} @Override
public void onBindNormalViewHolder(RecyclerView.ViewHolder holder, int position) {
DesignViewHolder viewHolder = (DesignViewHolder)holder;
DesignItem designItem = mDesignItems.get(position);
if (position == 10) {
//设置瀑布流的条目大小
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(260, 360);
lp.setMargins(10, 40, 10, 80);
viewHolder.cardView.setLayoutParams(lp);
} viewHolder.textView.setText(designItem.name);
}
}
Sample