41_RecyclerView添加头部和底部

Android基础汇总

Demo地址：http://download.youkuaiyun.com/detail/baopengjian/9885502

#1 原理：

RecyclerView没有暴露添加head和foot的方法，需要自行封装

利用不同的type添加ViewHolder即可，注意插入的位置和当LayoutManger为GridLayoutManger时，head和foot要独立的占一行。

 

#2 效果图：

 

#3 代码：

1）定义适配器（其他地方和普通使用时一样，主要是在适配器上做修改）：

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyHolder> {
private RecyclerView mRecyclerView;

private List<String> data = new ArrayList<>();
private Context mContext;

private View VIEW_FOOTER;
private View VIEW_HEADER;

//Type
private int TYPE_NORMAL = 1000;
private int TYPE_HEADER = 1001;
private int TYPE_FOOTER = 1002;

public MyAdapter(List<String> data, Context mContext){
this.data = data;
this.mContext = mContext;
}

@Override
public MyHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_FOOTER) {
return new MyHolder(VIEW_FOOTER);
} else if (viewType == TYPE_HEADER) {
return new MyHolder(VIEW_HEADER);
} else {
return new MyHolder(getLayout(R.layout.item_list_layout));
}
}

@Override
public void onBindViewHolder(MyHolder holder, int position) {
if (!isHeaderView(position) && !isFooterView(position)) {
if (haveHeaderView()) position--;
TextView content = holder.itemView.findViewById(R.id.item_content);
TextView time = holder.itemView.findViewById(R.id.item_time);
content.setText(data.get(position));
time.setText("2016-1-1");
}
}


@Override
public int getItemCount() {
int count = (data == null ? 0 : data.size());
if (VIEW_FOOTER != null) {
count++;
}

if (VIEW_HEADER != null) {
count++;
}
return count;
}

@Override
public int getItemViewType(int position) {
if (isHeaderView(position)) {
return TYPE_HEADER;
} else if (isFooterView(position)) {
return TYPE_FOOTER;
} else {
return TYPE_NORMAL;
}
}

@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
try {
if (mRecyclerView == null && mRecyclerView != recyclerView) {
mRecyclerView = recyclerView;
}
ifGridLayoutManager();
} catch (Exception e) {
e.printStackTrace();
}
}

private View getLayout(int layoutId) {
return LayoutInflater.from(mContext).inflate(layoutId, null);
}

public void addHeaderView(View headerView) {
if (haveHeaderView()) {
throw new IllegalStateException("hearview has already exists!");
} else {
//避免出现宽度自适应
ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
headerView.setLayoutParams(params);
VIEW_HEADER = headerView;
ifGridLayoutManager();
notifyItemInserted(0);
}

}

public void addFooterView(View footerView) {
if (haveFooterView()) {
throw new IllegalStateException("footerView has already exists!");
} else {
ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
footerView.setLayoutParams(params);
VIEW_FOOTER = footerView;
ifGridLayoutManager();
notifyItemInserted(getItemCount() - 1);
}
}

private void ifGridLayoutManager() {
if (mRecyclerView == null) return;
final RecyclerView.LayoutManager layoutManager = mRecyclerView.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
((GridLayoutManager) layoutManager).setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {
return (isHeaderView(position) || isFooterView(position)) ?
((GridLayoutManager) layoutManager).getSpanCount() :
1;
}
});
}
}

private boolean haveHeaderView() {
return VIEW_HEADER != null;
}

public boolean haveFooterView() {
return VIEW_FOOTER != null;
}

private boolean isHeaderView(int position) {
return haveHeaderView() && position == 0;
}

private boolean isFooterView(int position) {
return haveFooterView() && position == getItemCount() - 1;
}
public static class MyHolder extends RecyclerView.ViewHolder {
public MyHolder(View itemView) {
super(itemView);
}
}

}

 

（2）使用Adapter

public void linearLayout(View view){

LinearLayoutManager manager = new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);
rv.setLayoutManager(manager);
MyAdapter adapter = new MyAdapter(mDatas,this);


TextView tv = new TextView(this);
tv.setText("This is head");
tv.setTextSize(TypedValue.COMPLEX_UNIT_DIP,32);

TextView foot = new TextView(this);
foot.setText("This is foot");
foot.setTextSize(TypedValue.COMPLEX_UNIT_DIP,32);
adapter.addHeaderView(tv);
adapter.addFooterView(foot);

rv.setAdapter(adapter);
}

public void gridLayout(View view){
GridLayoutManager manager = new GridLayoutManager(this,3);
rv.setLayoutManager(manager);
MyAdapter adapter = new MyAdapter(mDatas,this);


TextView tv = new TextView(this);
tv.setText("This is head");
tv.setTextSize(TypedValue.COMPLEX_UNIT_DIP,32);

TextView foot = new TextView(this);
foot.setText("This is foot");
foot.setTextSize(TypedValue.COMPLEX_UNIT_DIP,32);
adapter.addHeaderView(tv);
adapter.addFooterView(foot);

rv.setAdapter(adapter);
}

 

#4 Demo：

demo09 RecyclerViewHeadFoot