标签：不同的 footview 而且 cli 网格 super string 决定 lstat
1.前言
Andriod中上拉加载更多的效果随处可见,因为一次性要展现的数据太多信息量太大的话,给用户的体验就很差(加载慢,界面卡顿、流量消耗大等),而加载更多可以控制每次加载条目的数量以达到快速加载,底部加载更多的方式就显得更人性化,今天就把用过的几种方式总结一下.
2.上拉加载更多的实现方式
它并没有现成的下拉刷新和上拉加载的实现.下拉刷新可以配合SwipeRefreshView实现,这个较简单,来看下RecyclerView的加载更多实现方式.
思路:recyclerView.addOnScrollListener(...),通过监听recyclerview的滚动状态,判断是滚动状态且最后可见条目是最后一条时,加载更多.
final LinearLayoutManager layoutManager = new LinearLayoutManager(this);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(adapter);
recyclerView.setHasFixedSize(true);
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) {
Log.d("==MainActivity==", "onScrolledStart");
super.onScrolled(recyclerView, dx, dy);
int lastVisibleItemPosition = layoutManager.findLastVisibleItemPosition();
int count = adapter.getItemCount();
if (lastVisibleItemPosition + 1 == count )
{
Log.d("==MainActivity==", "loading excute");
if (!isLoading) {
isLoading = true;
handler.postDelayed(new Runnable() {
@Override
public void run() {
isLoading = false;
//加载更多数据
addData();
}
}, 2000);
}
}
}
});public void addData() {
adapter.addData(originalData);
}
public class RecyclerViewAdapter extends RecyclerView.Adapter<ViewHolder> {
private static final int TYPE_ITEM = 0;
private static final int TYPE_FOOTER = 1;
private Context context;
private List<Map<String,Object>> datas;
public RecyclerViewAdapter(Context context) {
this.context = context;
datas = new ArrayList();
}
public void addData(List data) {
datas.addAll(data);
this.notifyItemRangeChanged(0, datas.size());
}
public interface OnItemClickListener {
void onItemClicked(View view, int position);
void onItemLongClicked(View view, int position);
}
private OnItemClickListener onItemClickListener;
public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
this.onItemClickListener = onItemClickListener;
}
@Override
public int getItemCount() {
int aa = datas.size() == 0 ? 0 : datas.size() + 1;
return aa;
}
@Override
public int getItemViewType(int position) {
if (position + 1 == getItemCount()) {
return TYPE_FOOTER;
} else {
return TYPE_ITEM;
}
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//加载每个列表项
if (viewType == TYPE_ITEM) {
View view = LayoutInflater.from(context).inflate(R.layout.item_base, parent, false);
return new ItemViewHolder(view);
}
if (viewType == TYPE_FOOTER) {
View view = LayoutInflater.from(context).inflate(R.layout.item_foot, parent, false);
return new FootViewHolder(view);
}
return null;
}
@Override
public void onBindViewHolder(final ViewHolder holder, int position) {
//加载每个列表项的数据
if (holder instanceof ItemViewHolder) {
Map<String, Object> listItem = datas.get(position);
((ItemViewHolder) holder).name.setText((String)listItem.get("personName") + " ------------" + String.valueOf(position));
((ItemViewHolder) holder).decs.setText((String)listItem.get("desc"));
((ItemViewHolder) holder).header.setImageResource((int)listItem.get("header"));
if (onItemClickListener != null) {
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int position = holder.getLayoutPosition();
onItemClickListener.onItemClicked(holder.itemView, position);
}
});
holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
int position = holder.getLayoutPosition();
onItemClickListener.onItemLongClicked(holder.itemView, position);
return false;
}
});
}
}
}
static class ItemViewHolder extends ViewHolder {
TextView name;
TextView decs;
ImageView header;
public ItemViewHolder(View view) {
super(view);
decs = (TextView)view.findViewById(R.id.desc);
name = (TextView)view.findViewById(R.id.name);
header = (ImageView)view.findViewById(R.id.header);
}
}
static class FootViewHolder extends ViewHolder {
public FootViewHolder(View view) {
super(view);
}
}
}
值得注意的就是getItemCount()方法返回的是数据总条目数+1,getItemViewType(int position) 方法返回当前position对应的条目类型,既然要底部加载更多,那就是2种不同的类型;
而onCreateViewHolder(ViewGroup parent, int viewType) 肯定是返回对应的这两种ViewHolder;onBindViewHolder方法就是依据holder决定绑定对应怎样的视图.
3.对RecyclerView二次封装的开源框架;常用的有UltimateRecyclerView(解决RecyclerView下拉刷新，加载更多，增加头部，显示或隐藏工具栏等许多问题的知名开源框架)、
PullLoadMoreRecyclerView(属性最全,实现了RecyclerView下拉刷新和上拉加载更多以及RecyclerView线性、网格、瀑布流效果)、SwipeToLoadLayout支持多种基于RecyclerView的上拉加载和下拉刷新样式;
以PullLoadMoreRecyclerView为例子简单介绍其使用方式:
build.gradle添加依赖:
dependencies { compile ‘com.wuxiaolong.pullloadmorerecyclerview:library:1.0.4‘ } mPullLoadMoreRecyclerView = (PullLoadMoreRecyclerView) view.findViewById(R.id.pullLoadMoreRecyclerView); mPullLoadMoreRecyclerView.setLinearLayout(); mPullLoadMoreRecyclerView.setOnPullLoadMoreListener(new PullLoadMoreRecyclerView.PullLoadMoreListener() { @Override public void onRefresh() {//下拉刷新时调用 } @Override public void onLoadMore() {//上拉加载更多时调用 } })mPullLoadMoreRecyclerView.setPullLoadMoreCompleted();//加载结束时调用
此外还有很多个性化的接口方法暴露,很方便开发时使用.这里就不一一介绍了.具体可以去Github上搜索.
3.总结
按时间来说,我用得最多的是ListView,但是头布局越来越多后,position的转换显得很麻烦,而且recyclerview的缓存和回收机制更高效,recyclerview早就挡不住了,
listview和Gridview正在被recycleview替代,了解一些优秀的开源框架对开发事半功倍,但是我要强调的是这些框架的具体实现原理如果搞懂的话,可以形成自己的东西,有时间自己也能写出高效的框架来.后面也会深入理解.
标签：不同的 footview 而且 cli 网格 super string 决定 lstat
原文地址：http://www.cnblogs.com/fuyaozhishang/p/6624833.html
