如何为RecyclerView添加Header和Footer

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package com.study.wnw.recyclerviewheaderfooter; 
import android.app.Activity;import android.os.Bundle; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.view.LayoutInflater; 
import android.view.View; 
import java.util.ArrayList;import java.util.List; 

public class MainActivity extends Activity { 
 private RecyclerView mRecyclerView; 
 private MyAdapter mMyAdapter; 
 private List mList; 

 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 

  //RecyclerView三部曲+LayoutManager  
  mRecyclerView = (RecyclerView)findViewById(R.id.recyclerview); 
  LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this); 
  mRecyclerView.setLayoutManager(linearLayoutManager); 
  initData(); 
  mMyAdapter = new MyAdapter(mList); 
  mRecyclerView.setAdapter(mMyAdapter); 

 //为RecyclerView添加HeaderView和FooterView 
  setHeaderView(mRecyclerView); 
  setFooterView(mRecyclerView); 
 } 

 //初始化RecyclerView中每个item的数据 
 private void initData(){ 
 mList = new ArrayList(); 
 for (int i = 0; i <20; i++){ 
  mList.add("item" + i); 
 } 
 } 

 private void setHeaderView(RecyclerView view){ 
 View header = LayoutInflater.from(this).inflate(R.layout.header, view, false); 
  mMyAdapter.setHeaderView(header); 
 } 

 private void setFooterView(RecyclerView view){ 
 View footer = LayoutInflater.from(this).inflate(R.layout.footer, view, false);  
 mMyAdapter.setFooterView(footer); 
 } 
}

package com.study.wnw.recyclerviewheaderfooter;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.List;
/** * Created by wnw on 16-5-20. */
public class MyAdapter extendsRecyclerView.Adapter { 
 public static final int TYPE_HEADER = 0; //说明是带有Header的 
 public static final int TYPE_FOOTER = 1; //说明是带有Footer的 
 public static final int TYPE_NORMAL = 2; //说明是不带有header和footer的

 //获取从Activity中传递过来每个item的数据集合 
 private List mDatas;
 //HeaderView, FooterView 
 private View mHeaderView; 
 private View mFooterView; 

 //构造函数 
 public MyAdapter(List list){ 
 this.mDatas = list; 
 } 

 //HeaderView和FooterView的get和set函数 
 public View getHeaderView() { 
 return mHeaderView; 
 } 
 public void setHeaderView(View headerView) { 
 mHeaderView = headerView; 
 notifyItemInserted(0); 
 } 
 public View getFooterView() { 
 return mFooterView; 
 } 
 public void setFooterView(View footerView) { 
 mFooterView = footerView; 
 notifyItemInserted(getItemCount()-1); 
 } 

 /** 重写这个方法，很重要，是加入Header和Footer的关键，我们通过判断item的类型，从而绑定不同的view * */ 
 @Override
 public int getItemViewType(int position) {  
 if (mHeaderView == null && mFooterView == null){  
  return TYPE_NORMAL; 
 } 
 if (position == 0){  
  //第一个item应该加载Header  
  return TYPE_HEADER; 
 } 
 if (position == getItemCount()-1){  
  //最后一个,应该加载Footer  
  return TYPE_FOOTER; 
 } 
 return TYPE_NORMAL; 
 } 

 //创建View，如果是HeaderView或者是FooterView，直接在Holder中返回  
 @Override 
 public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
 if(mHeaderView != null && viewType == TYPE_HEADER) {  
  return new ListHolder(mHeaderView); 
 } 
 if(mFooterView != null && viewType == TYPE_FOOTER){  
  return new ListHolder(mFooterView); 
 } 
 View layout = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item, parent, false); 
 return new ListHolder(layout); 
 } 

 //绑定View，这里是根据返回的这个position的类型，从而进行绑定的， HeaderView和FooterView, 就不同绑定了 
 @Override 
 public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) { 
 if(getItemViewType(position) == TYPE_NORMAL){  
  if(holder instanceof ListHolder) {  
  //这里加载数据的时候要注意，是从position-1开始，因为position==0已经被header占用了  
  ((ListHolder) holder).tv.setText(mDatas.get(position-1));  
  return;  
  }  
  return; 
 }else if(getItemViewType(position) == TYPE_HEADER){  
  return;  
 }else{  
  return; 
  } 
 } 

 //在这里面加载ListView中的每个item的布局 
 class ListHolder extends RecyclerView.ViewHolder{ 
 TextView tv; 
 public ListHolder(View itemView) {  
  super(itemView);  
  //如果是headerview或者是footerview,直接返回  
  if (itemView == mHeaderView){  
  return;  
  }  
  if (itemView == mFooterView){  
  return;  
  }  
  tv = (TextView)itemView.findViewById(R.id.item); 
  } 
 } 

 //返回View中Item的个数，这个时候，总的个数应该是ListView中Item的个数加上HeaderView和FooterView 
 @Override 
 public int getItemCount() { 
 if(mHeaderView == null && mFooterView == null){  
  return mDatas.size(); 
 }else if(mHeaderView == null && mFooterView != null){  
  return mDatas.size() + 1; 
 }else if (mHeaderView != null && mFooterView == null){  
  return mDatas.size() + 1; 
 }else {  
  return mDatas.size() + 2; 
 } 
 }
}