4. LayoutManager
管理RecyclerView的布局结构.
private void initRecyclerLayoutManager(RecyclerView recyclerView) {
// 错列网格布局
recyclerView.setLayoutManager(new StaggeredGridLayoutManager(4,
StaggeredGridLayoutManager.VERTICAL));
}
提供了多种LayoutManager, 瀑布流使用错列网格布局.
5. Adapter
适配器, 处理RecyclerView的Item事务.
private void initRecyclerAdapter(RecyclerView recyclerView) {
mAdapter = new MyAdapter(getData());
recyclerView.setAdapter(mAdapter);
}
对于Adapter, 我们需要展开来说, 先看看类.
public class MyAdapter extends RecyclerView.Adapter<MyViewHolder> {
private List<DataModel> mDataModels;
private List<Integer> mHeights;
MyAdapter(List<DataModel> dataModels) {
if (dataModels == null) {
throw new IllegalArgumentException("DataModel must not be null");
}
mDataModels = dataModels;
mHeights = new ArrayList<>();
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_recycler_view, parent, false);
return new MyViewHolder(itemView);
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
DataModel dataModel = mDataModels.get(position);
// 随机高度, 模拟瀑布效果.
if (mHeights.size() <= position) {
mHeights.add((int) (100 + Math.random() * 300));
}
ViewGroup.LayoutParams lp = holder.getTvLabel().getLayoutParams();
lp.height = mHeights.get(position);
holder.getTvLabel().setLayoutParams(lp);
holder.getTvLabel().setText(dataModel.getLabel());
holder.getTvDateTime().setText(new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH)
.format(dataModel.getDateTime()));
}
@Override
public int getItemCount() {
return mDataModels.size();
}
public void addData(int position) {
DataModel model = new DataModel();
model.setDateTime(getBeforeDay(new Date(), position));
model.setLabel("No. " + (int) (new Random().nextDouble() * 20.0f));
mDataModels.add(position, model);
notifyItemInserted(position);
}
public void removeData(int position) {
mDataModels.remove(position);
notifyItemRemoved(position);
}
/**
* 获取日期的前一天
*
* @param date 日期
* @param i 偏离
* @return 新的日期
*/
private static Date getBeforeDay(Date date, int i) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.add(Calendar.DAY_OF_YEAR, i * (-1));
return calendar.getTime();
}
}
