为RecyclerView添加Header和Footer，支持三种LayoutManager

public abstract class RecyclerHeaderFooterAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {

private static final int ITEM_TYPE_HEADER = 1;
private static final int ITEM_TYPE_FOOTER = 2;

private boolean headerEnable;
private boolean footerEnable;
private boolean singleLineHeaderEnable;
private boolean singleLineFooterEnable;

private OnItemClickListener onItemClickListener;
private OnItemLongLickListener onItemLongLickListener;

@Override
public final VH onCreateViewHolder(ViewGroup parent, int viewType) {

if (viewType == ITEM_TYPE_HEADER) {

return onCreateHeaderViewHolder(parent, viewType);
} else if (viewType == ITEM_TYPE_FOOTER) {

return onCreateFooterViewHolder(parent, viewType);
} else {

return onCreateContentViewHolder(parent, viewType - ITEM_TYPE_HEADER - ITEM_TYPE_FOOTER);
}
}

@Override
public final void onBindViewHolder(final VH holder, final int position) {

int viewType = holder.getItemViewType();
if (viewType == ITEM_TYPE_HEADER) {

onBindHeaderViewHolder(holder, position);
} else if (viewType == ITEM_TYPE_FOOTER) {

final int headerCount = isHeaderEnable() ? getHeaderItemCount() : 0;
final int contentCount = getContentItemCount();
onBindFooterViewHolder(holder, position - headerCount - contentCount);
} else {

final int headerCount = isHeaderEnable() ? getHeaderItemCount() : 0;
onBindContentViewHolder(holder, position - headerCount);
if (onItemClickListener != null) {

holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {

onItemClickListener.onItemClick(holder, position - headerCount);
}
});
}

if (onItemLongLickListener != null) {

holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {

return onItemLongLickListener.onItemLongClick(holder, position - headerCount);
}
});
}
}
}

@Override
public final long getItemId(int position) {

final int validHeaderCount = isHeaderEnable() ? getHeaderItemCount() : 0;
final int contentItemCount = getContentItemCount();
if (position < validHeaderCount) {

return getHeaderItemId(position);
} else if (position < validHeaderCount + contentItemCount) {

return getContentItemId(position - validHeaderCount);
} else {

return getContentItemId(position - validHeaderCount - contentItemCount);
}
}

@Override
public final int getItemCount() {

int itemCount = 0;

if (isHeaderEnable()) {
itemCount += getHeaderItemCount();
}

if (isFooterEnable()) {
itemCount += getFooterItemCount();
}

itemCount += getContentItemCount();

return itemCount;
}

@Override
public final int getItemViewType(int position) {

final int validHeaderCount = isHeaderEnable() ? getHeaderItemCount() : 0;

if (position < validHeaderCount) {

return ITEM_TYPE_HEADER;
} else if (position < validHeaderCount + getContentItemCount()) {

int contentItemViewType = getContentItemViewType(position - validHeaderCount);
if (contentItemViewType <= 0) {

throw new IllegalArgumentException("getContentItemViewType must return a value > 0");
}
return contentItemViewType + ITEM_TYPE_HEADER + ITEM_TYPE_FOOTER;
} else {

return ITEM_TYPE_FOOTER;
}
}

public VH onCreateHeaderViewHolder(ViewGroup parent, int viewType) {
return null;
}

public VH onCreateFooterViewHolder(ViewGroup parent, int viewType) {
return null;
}

public abstract VH onCreateContentViewHolder(ViewGroup parent, int viewType);

public abstract void onBindContentViewHolder(VH holder, int position);

public void onBindFooterViewHolder(VH holder, int position) {
}

public void onBindHeaderViewHolder(VH holder, int position) {
}

public int getHeaderItemCount() {
return 0;
}

public int getFooterItemCount() {
return 0;
}

public abstract int getContentItemCount();

public int getContentItemViewType(int position) {
return 1;
}

protected long getContentItemId(int position) {
return RecyclerView.NO_ID;
}

protected long getFooterItemId(int position) {
return RecyclerView.NO_ID;
}

protected long getHeaderItemId(int position) {
return RecyclerView.NO_ID;
}

public final boolean isHeaderEnable() {
return headerEnable;
}

public void setHeaderEnable(boolean headerEnable) {

if (!(isHeaderEnable() && headerEnable)) {

notifyDataSetChanged();
this.headerEnable = headerEnable;
}
}

public final boolean isFooterEnable() {
return footerEnable;
}

public void setFooterEnable(boolean footerEnable) {

if (!(isFooterEnable() && footerEnable)) {

final int validHeaderCount = isHeaderEnable() ? getHeaderItemCount() : 0;
notifyItemRangeRemoved(validHeaderCount + getContentItemCount(), getFooterItemCount());
this.footerEnable = footerEnable;
}
}

public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
this.onItemClickListener = onItemClickListener;
}

public void setOnItemLongLickListener(OnItemLongLickListener onItemLongLickListener) {
this.onItemLongLickListener = onItemLongLickListener;
}

public boolean isHeaderItem(int position){

return isHeaderEnable() && position < getHeaderItemCount();
}

public boolean isContentItem(int position){

final int validHeaderCount = isHeaderEnable() ? getHeaderItemCount() : 0;
final int validFooterCount = isFooterEnable() ? getFooterItemCount() : 0;
return position >= validHeaderCount && position < getItemCount() - validFooterCount;
}

public boolean isFooterItem(int position){

final int validHeaderCount = isHeaderEnable() ? getHeaderItemCount() : 0;
return position >= getItemCount() - getContentItemCount()- validHeaderCount;
}

@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);

RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
if(layoutManager instanceof GridLayoutManager){

final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
final GridLayoutManager.SpanSizeLookup oldSizeLookup = gridLayoutManager.getSpanSizeLookup();

gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {

if(isHeaderItem(position) && singleLineHeaderEnable){
return gridLayoutManager.getSpanCount();
}
if(isFooterItem(position) && singleLineFooterEnable){
return gridLayoutManager.getSpanCount();
}
if(oldSizeLookup != null){
return oldSizeLookup.getSpanSize(position);
}
return 0;
}
});
}
}

@Override
public void onViewAttachedToWindow(VH holder) {
super.onViewAttachedToWindow(holder);

int position = holder.getLayoutPosition();
if (isHeaderItem(position) && singleLineHeaderEnable || isFooterItem(position) && singleLineFooterEnable) {

ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();

if (lp != null && lp instanceof StaggeredGridLayoutManager.LayoutParams) {

StaggeredGridLayoutManager.LayoutParams p = (StaggeredGridLayoutManager.LayoutParams) lp;

p.setFullSpan(true);
}
}
}

public boolean isSingleLineHeaderEnable() {
return singleLineHeaderEnable;
}

public void setSingleLineHeaderEnable(boolean singleLineHeaderEnable) {
this.singleLineHeaderEnable = singleLineHeaderEnable;
}

public boolean isSingleLineFooterEnable() {
return singleLineFooterEnable;
}

public void setSingleLineFooterEnable(boolean singleLineFooterEnable) {
this.singleLineFooterEnable = singleLineFooterEnable;
}