RecyclerView Adapter封装2——多类型Item 的Adapter封装
在上一篇RecyclerView Adapter封装1—单类型Item 的Adapter封装中分析了RecyclerView 的Adapter,并对单类型Item的Adapter进行了封装
这一篇继续对多类型Item 的Adapter进行封装。
多类型Adapter代码分析
下面是一个很简单的多类型Adapter，分析代码找出共同点进行抽取封装
public class MultiItemTypeAdapter extends RecyclerView.Adapter {
private Context mContext;
private LayoutInflater mLayoutInflater;//布局渲染器
public static final int TYPE_1 = 0; //类型1
public static final int TYPE_2 = 1; //类型2
private List<MultiItem> mDatas;
public MultiItemTypeAdapter(Context context, List<MultiItem> datas) {
this.mContext = context;
mLayoutInflater = LayoutInflater.from(context);
this.mDatas = datas;
}
@Override
public int getItemViewType(int position) {
int itemType = 0;
int type = mDatas.get(position).getType(); //判断类型
switch (type) {
case TYPE_1:
itemType = TYPE_1;
break;
case TYPE_2:
itemType = TYPE_2;
break;
}
return itemType;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//根据不同的类型来创建 ViewHolder
if (viewType == TYPE_1) {
return new Type1Holder(mLayoutInflater.inflate(R.layout.item_type1, parent, false));
} else if (viewType == TYPE_2) {
return new Type2Holder(mLayoutInflater.inflate(R.layout.item_type2, parent, false));
}
return null;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
//根据类型来区分绑定数据
if (getItemViewType(position) == TYPE_1) {
Type1Holder type1Holder = (Type1Holder) holder;
type1Holder.tv_type1.setText(mDatas.get(position).getContent());
} else if (getItemViewType(position) == TYPE_2) {
Type2Holder type2Holder = (Type2Holder) holder;
type2Holder.tv_type2.setText(mDatas.get(position).getContent());
}
}
//类型1 对应的ViewHolder
public class Type1Holder extends RecyclerView.ViewHolder {
public TextView tv_type1;
public Type1Holder(View itemView) {
super(itemView);
tv_type1 = (TextView) itemView.findViewById(R.id.tv_type1);
}
}
//类型1 对应的ViewHolder
public class Type2Holder extends RecyclerView.ViewHolder {
public TextView tv_type2;
public Type2Holder(View itemView) {
super(itemView);
tv_type2 = (TextView) itemView.findViewById(R.id.tv_type2);
}
}
@Override
public int getItemCount() {
return mDatas == null ? 0 : mDatas.size();
}
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
final GridLayoutManager gridManager = ((GridLayoutManager) layoutManager);
gridManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {
//类型1需要在网格布局时 占据全行
int type = getItemViewType(position);
return type == TYPE_1 ? 1 : gridManager.getSpanCount();
}
});
}
}
}
以上代码中
**getItemType() **方法很重要，这是分类型的前提，RecyclerView进行展示的时候回来调用这个方法确定Item 的类型
onCreateViewHolder方法，参方法的参数viewType即为getItemType()方法返回的类型，在此方法中我们可以根据类型创建不同的ViewHolder保存View
onBindViewHolder方法，需要在此方法中判断类型，并给不同类型的ItemView 绑定数据
onAttachedToRecyclerView方法,这个方法不是必要的
但是当某个类型占据一整行，另一个类型只需要一列的情况，这个方法就可以起作用了。
分析MultiItemTypeAdapter的代码发现，我们重点关心的是
1、每一个类型的Type,什么时候绑定当前的Type
4、每个类型对应layoutId
3、每个类型都有不同的ViewHolder，对于这个问题，我们已经在RecyclerView Adapter封装1—单类型Item 的Adapter封装封装了通用的ViewHolder
4、每个类型如何绑定数据
MultiItemTypeAdapter代码封装
经过以上的分析，明确了四个要素点
① 类型的Type ②类型何时需要被绑定 ③类型的layoutId ④如何绑定数据
1、关于Type和类型何时需要被绑定
在最初的时候采用了拓展Bean类来实现
public interface MultiType {
int getItemType();
}
由Bean 实现此接口来提供ItemType,使用泛型限定类型为MultiItemTypeAdapter<? extends MultiType>代码就可以写为：
@Override
public int getItemViewType(int position) {
return mDats.getItemType();
}
之后觉得这样对Bean类的侵入性较强，需要处理数据，就放弃了这种写法。
2、通过分析，发现每一种类型相对独立，那么可以按照封装性的原则将每一种类型封装成一个Delegate，然后统一进行管理
public interface ItemViewDelegate<T>
{
//获取Item类型
int getItemType();
//是否绑定数据
boolean isForViewType(T item, int position);
//类型的Item
int getItemViewLayoutId();
//绑定数据
void convert(ViewHolder holder, T t, int position);
}
针对四个要素抽象出四个接口由子类去提供，接下来重点就在于Delegate 的管理类 ItemViewDelegateManager
对于MultiItemTypeAdapter，可见的只有ItemViewDelegateManager类，通过ItemViewDelegateManager来管理多种类型，具体的类型提供和绑定由ItemViewDelegateManager内部来完成
ItemViewDelegateManager的职责：
1、通过分析getItemViewType(int position) 方法 该类需要提供 根据 position 来获取ItemType 的方法
2、通过分析onCreateViewHolder() 方法，该类需要提供**根据itemType来获取layoutId **的方法，用来创建通用的ViewHolder
3、通过分析onBindViewHolder()方法，该类需要提供 根据position 来绑定数据 的方法
3、ItemViewDelegateManager代码
public class ItemViewDelegateManager<T> {
//存储类型的容器
SparseArray<ItemViewDelegate<T>> delegates = new SparseArray();
public int getItemViewDelegateCount() {
return delegates.size();
}
public ItemViewDelegateManager<T> addDelegate(ItemViewDelegate<T> delegate) {
int viewType = delegate.getItemType();
//判断之前是否已经添加过
if (delegates.get(viewType) != null) {
throw new IllegalArgumentException(
"An ItemViewDelegate is already registered for the viewType = "
+ viewType
+ ". Already registered ItemViewDelegate is "
+ delegates.get(viewType));
}
delegates.put(viewType, delegate);
return this;
}
public ItemViewDelegateManager<T> removeDelegate(ItemViewDelegate<T> delegate) {
int indexToRemove = delegates.indexOfValue(delegate);
if (indexToRemove >= 0) {
delegates.removeAt(indexToRemove);
}
return this;
}
public ItemViewDelegateManager<T> removeDelegate(int itemType) {
int indexToRemove = delegates.indexOfKey(itemType);
if (indexToRemove >= 0) {
delegates.removeAt(indexToRemove);
}
return this;
}
//根据position 来获取类型
public int getItemViewType(T item, int position) {
int delegatesCount = delegates.size();
for (int i = 0; i <delegatesCount; i++) {
ItemViewDelegate<T> delegate = delegates.valueAt(i);
if (delegate.isForViewType(item, position)) {
return delegates.keyAt(i);
}
}
//没有添加过抛出异常
throw new IllegalArgumentException(
"No ItemViewDelegate added that matches position=" + position);
}
//根据类型来绑定数据
public void convert(ViewHolder holder, T item, int position) {
int delegatesCount = delegates.size();
for (int i = 0; i < delegatesCount; i++) {
ItemViewDelegate<T> delegate = delegates.valueAt(i);
if (delegate.isForViewType(item, position)) {
delegate.convert(holder, item, position);
return;
}
}
throw new IllegalArgumentException(
"No ItemViewDelegateManager added that matches position=" + position + " in data source");
}
//根据type获取getItemViewDelegate对象
public ItemViewDelegate getItemViewDelegate(int viewType) {
return delegates.get(viewType);
}
//根据viewType获取对应的layoutId
public int getItemViewLayoutId(int viewType) {
return getItemViewDelegate(viewType).getItemViewLayoutId();
}
//获取指定ItemViewDelegate对应的类型
public int getItemViewType(ItemViewDelegate itemViewDelegate) {
return delegates.indexOfValue(itemViewDelegate);
}
}
存储的容器还是采用SparseArray，SparseArray在这样保存的key为 int型itemType的场景下非常好用。
- addDelegate(ItemViewDelegate<T> delegate)方法 ，将ItemViewDelegate添加到容器中，key 为 ItemViewDelegate对应的itemType
- 着重分析一下getItemViewType()方法
public int getItemViewType(T item, int position) {
int delegatesCount = delegates.size();
for (int i = 0; i <delegatesCount; i++) {
ItemViewDelegate<T> delegate = delegates.valueAt(i);
if (delegate.isForViewType(item, position)) {
return delegates.keyAt(i);
}
}
//没有添加过抛出异常
throw new IllegalArgumentException(
"No ItemViewDelegate added that matches position=" + position);
}
对于一种类型，你不能确定什么时候来绑定这种类型，可能是1、3、5，也可能是2、4、6，所以才有了isForViewType(T item, int position)来判断某个位置是否需要绑定，而类型现在存储在SparseArray中，所以需要通过循环来判定 某个position 需要哪一个ItemViewDelegate来进行绑定
- convert(ViewHolder holder, T item, int position)方法与getItemType同理，判断哪一个类型需要绑定，直接进行绑定
- getItemViewLayoutId() 直接根据type 在SparseArray匹配ItemViewDelegate获取layoutId
4、MultiItemTypeAdapter实现
public class MultiItemTypeAdapter<T> extends RecyclerView.Adapter<ViewHolder> {
protected Context mContext;
//数据集合
protected List<T> mDatas;
//类型管理器
protected ItemViewDelegateManager mItemViewDelegateManager;
protected OnItemClickListener mOnItemClickListener;
private SparseArray<Integer> fullTypes = new SparseArray<>();
public MultiItemTypeAdapter(Context context, List<T> datas) {
mContext = context;
mDatas = datas;
mItemViewDelegateManager = new ItemViewDelegateManager();
}
@Override
public int getItemViewType(int position) {
return mItemViewDelegateManager.getItemViewType(mDatas.get(position), position);
}
public void clearData() {
mDatas.clear();
notifyItemRangeRemoved(0, mDatas.size());
}
public void removeData(int position) {
mDatas.remove(position);
notifyItemRemoved(position);
if (position != mDatas.size())
notifyItemRangeChanged(position, mDatas.size() - position);
}
public void remove(int position) {
mDatas.remove(position);
notifyDataSetChanged();
}
public void addData(List<T> list) {
addData(0, list);
}
public void addData(int position, List<T> data) {
if (data != null && data.size() > 0) {
mDatas.addAll(position, data);
notifyItemRangeInserted(position, data.size());
}
}
public void setData(List<T> list) {
if (list != null) {
mDatas = list;
notifyDataSetChanged();
}
}
public void refresh(List<T> data) {
clearData();
addData(data);
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
ItemViewDelegate itemViewDelegate = mItemViewDelegateManager.getItemViewDelegate(viewType);
int layoutId = itemViewDelegate.getItemViewLayoutId();
ViewHolder holder = ViewHolder.createViewHolder(mContext, parent, layoutId);
setListener(parent, holder, viewType);
return holder;
}
protected boolean isEnabled(int viewType) {
return true;
}
protected void setListener(final ViewGroup parent, final ViewHolder viewHolder, int viewType) {
if (!isEnabled(viewType)) return;
viewHolder.getConvertView().setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mOnItemClickListener != null) {
int position = viewHolder.position;
mOnItemClickListener.onItemClick(v, viewHolder, position);
}
}
});
viewHolder.getConvertView().setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
if (mOnItemClickListener != null) {
int position = viewHolder.position;
return mOnItemClickListener.onItemLongClick(v, viewHolder, position);
}
return false;
}
});
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.position = position;
mItemViewDelegateManager.convert(holder, mDatas.get(position), position);
}
@Override
public int getItemCount() {
return mDatas==null? 0: mDatas.size();
}
public List<T> getDatas() {
return mDatas;
}
public MultiItemTypeAdapter addItemViewDelegate(ItemViewDelegate<T> itemViewDelegate) {
mItemViewDelegateManager.addDelegate(itemViewDelegate);
return this;
}
public interface OnItemClickListener {
void onItemClick(View view, RecyclerView.ViewHolder holder, int position);
boolean onItemLongClick(View view, RecyclerView.ViewHolder holder, int position);
}
public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
this.mOnItemClickListener = onItemClickListener;
}
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
final GridLayoutManager gridManager = ((GridLayoutManager) layoutManager);
gridManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {
if (position >= mDatas.size()) {
return gridManager.getSpanCount();
}
int type = getItemViewType(position);
return isFullSpan(type) ? gridManager.getSpanCount() : 1;
}
});
}
}
private boolean isFullSpan(int type) {
return fullTypes.indexOfKey(type) >= 0;
}
public void setFullSpan(int... types) {
for (int type : types) {
fullTypes.put(type, type);
}
}
}
经过了以上的分析MultiItemTypeAdapter的代码就简单易懂了
这里特地说明以下代码：
private SparseArray<Integer> fullTypes = new SparseArray<>();
private boolean isFullSpan(int type) {
return fullTypes.indexOfKey(type) >= 0;
}
public void setFullSpan(int... types) {
for (int type : types) {
fullTypes.put(type, type);
}
}
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
final GridLayoutManager gridManager = ((GridLayoutManager) layoutManager);
gridManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {
if (position >= mDatas.size()) {
return gridManager.getSpanCount();
}
int type = getItemViewType(position);
return isFullSpan(type) ? gridManager.getSpanCount() : 1;
}
});
}
}
这里保存了一个占据全行type 的集合，在需要设置全行的时候调用 setFullSpan(int ...types)方法，将类型传入
并且在onAttachedToRecyclerView方法的代码中进行了判断调整为全行显示。
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