Android RecyclerView添加头部和底部的方法

<FrameLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content">

 <android.support.v7.widget.RecyclerView
  android:id="@+id/recycler"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:layout_gravity="center_horizontal|top" />

 <com.bartoszlipinski.recyclerviewheader.RecyclerViewHeader
  android:id="@+id/header"
  android:layout_width="match_parent"
  android:layout_height="100dp"
  android:layout_gravity="center_horizontal|top">

  <TextView
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_centerInParent="true"
   android:text="header"/>

 </com.bartoszlipinski.recyclerviewheader.RecyclerViewHeader>

</FrameLayout>

RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
// set LayoutManager for your RecyclerView
header.attachTo(recyclerView, true);

public class WrapRecyclerView extends RecyclerView {
 public ArrayList<View> mHeaderViews = new ArrayList<>();
 public ArrayList<View> mFooterViews = new ArrayList<>();
 //添加Adapter
 public Adapter mAdapter;
 public WrapRecyclerView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
 }

 public WrapRecyclerView(Context context, AttributeSet attrs) {
  super(context, attrs);
 }

 public WrapRecyclerView(Context context) {
  super(context);
 }
 public void addHeaderView(View view){
  mHeaderViews.clear();
  mHeaderViews.add(view);
  if(mAdapter!=null){
   if(!(mAdapter instanceof RecyclerWrapAdapter)){
    mAdapter = new RecyclerWrapAdapter(mHeaderViews,mFooterViews,mAdapter);
   }
  }
 }
 public void addFooterView(View view){
  mFooterViews.clear();
  mFooterViews.add(view);
  if(mAdapter!=null){
   if(!(mAdapter instanceof RecyclerWrapAdapter)){
    mAdapter = new RecyclerWrapAdapter(mHeaderViews,mFooterViews,mAdapter);
   }
  }
 }
 public void setAdapter(Adapter adapter){
  if (mHeaderViews.isEmpty()&&mFooterViews.isEmpty()){

   super.setAdapter(adapter);
  }else {
   adapter = new RecyclerWrapAdapter(mHeaderViews,mFooterViews,adapter) ;
   super.setAdapter(adapter);
  }
  mAdapter = adapter ;
 }
}

public class RecyclerWrapAdapter extends RecyclerView.Adapter implements WrapperAdapter{
 private RecyclerView.Adapter mAdapter;

 private ArrayList<View> mHeaderViews;

 private ArrayList<View> mFootViews;
 static final ArrayList<View> EMPTY_INFO_LIST =
   new ArrayList<View>();
 private int mCurrentPosition;
 public RecyclerWrapAdapter(ArrayList<View> mHeaderViews, ArrayList<View> mFootViews, RecyclerView.Adapter mAdapter){
  this.mAdapter = mAdapter;
  if (mHeaderViews == null) {
   this.mHeaderViews = EMPTY_INFO_LIST;
  } else {
   this.mHeaderViews = mHeaderViews;
  }
  if (mFootViews == null) {
   this.mFootViews = EMPTY_INFO_LIST;
  } else {
   this.mFootViews = mFootViews;
  }
 }

 public int getHeadersCount() {
  return mHeaderViews.size();
 }

 public int getFootersCount() {
  return mFootViews.size();
 }
 @Override
 public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
  if (viewType == RecyclerView.INVALID_TYPE) {
   return new HeaderViewHolder(mHeaderViews.get(0));
  } else if (viewType == RecyclerView.INVALID_TYPE - 1) {
   return new HeaderViewHolder(mFootViews.get(0));
  }
  return mAdapter.onCreateViewHolder(parent, viewType);
 }

 @Override
 public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
  //如果头部不为空，那么我们就要先添加头部，所以我们只要
  //把前面几个position给头部，当position小于头部总数的时候，
  //我们返回头部view。再判断原Adapter 的 count 与当前 position 
  // 的差值来比较，是调用原 Adapter 的 getView 方法，还是获取 footView
  // 的 view。
  int numHeaders = getHeadersCount();
  if (position < numHeaders) {
   return;
  }
  int adjPosition = position - numHeaders;
  int adapterCount = 0;
  if (mAdapter != null) {
   adapterCount = mAdapter.getItemCount();
   if (adjPosition < adapterCount) {
    mAdapter.onBindViewHolder(holder, adjPosition);
    return;
   }
  }
 }

 @Override
 public int getItemCount() {
  if (mAdapter != null) {
   return getHeadersCount() + getFootersCount() + mAdapter.getItemCount();
  } else {
   return getHeadersCount() + getFootersCount();
  }
 }

 @Override
 public RecyclerView.Adapter getWrappedAdapter() {
  return mAdapter;
 }
 @Override
 public int getItemViewType(int position) {
  //增加两个类型
  //RecyclerView.INVALID_TYPE 添加头部
  //RecyclerView.INVALID_TYPE-1 添加尾部
  //如果头部不为空，那么我们就要先添加头部，所以我们只要
  //把前面几个position给头部，当position小于头部总数的时候，
  //我们返回头部类型。再判断原Adapter 的 count 与当前 position 
  // 的差值来比较，是调用原 Adapter 的 类型，还是获取 footView
  // 的类型。
  mCurrentPosition = position ;
  int numHeaders = getHeadersCount();
  if(position<numHeaders){
   return RecyclerView.INVALID_TYPE ;
  }
  int adjPosition = position - numHeaders ;
  int adapterCount = 0 ;
  if(mAdapter!=null){
   adapterCount = mAdapter.getItemCount() ;
   if(adjPosition < adapterCount){
    return mAdapter.getItemViewType(adjPosition);
   }
  }
  return RecyclerView.INVALID_TYPE - 1;
 }
 private static class HeaderViewHolder extends RecyclerView.ViewHolder {
  public HeaderViewHolder(View itemView) {
   super(itemView);
  }
 }
}

public interface WrapperAdapter {

 public RecyclerView.Adapter getWrappedAdapter() ;
}