RecyclerView的使用(三)多布局
在项目中，我们经常用到多布局的情况，跟ListView一样，我们需要通过ViewType来进行区分。
界面效果如图：
这里写图片描述
（一）单布局的Adapter
首先我们看下以前单布局的Adapter是如何去写的：
我们继承了RecyclerView.Adapter，泛型是MyAdapter 中继承的ViewHolder类，这样写后我们的onCreateViewHolder和onBindViewHolder的方法参数都是我们的ViewHolder了，是无法做到区分多布局的。
class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder>{
@Override
public MyAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return null;
}
@Override
public void onBindViewHolder(MyAdapter.MyViewHolder holder, int position) {
}
@Override
public int getItemCount() {
return 0;
}
//继承RecyclerView.ViewHolder
class MyViewHolder extends RecyclerView.ViewHolder{
public MyViewHolder(View itemView) {
super(itemView);
}
}
}
（二）多布局的Adapter
多布局的Adapter我们泛型为RecyclerView.ViewHolder，通过ViewType，我们区分使用不同的ViewHolder。
RecyclerView提供了方法去区分ViewType
@Override
public int getItemViewType(int position) {
return super.getItemViewType(position);
}
onCreateViewHolder的第二个参数int viewType就是getItemViewType的返回值
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return null;
}
在onBindViewHolder中，我们的来绑定布局
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
}
我们看看如何去实现，我们首先定义两个标志,
public static final int ONE_ITEM = 1;
public static final int TWO_ITEM = 2;
代码奉上
import android.support.v7.app.AppCompatActivity;
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 android.view.ViewGroup;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
public class ViewTypeActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private List<String> mDatas;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initData();
setContentView(R.layout.activity_water_full);
mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
mRecyclerView.addItemDecoration(new SpacesItemDecoration(12));
mRecyclerView.setAdapter(new ViewTypeAdapter());
}
private void initData() {
mDatas = new ArrayList<String>();
for (int i = 0; i < 24; i++) {
mDatas.add("位置是" + i);
}
}
class ViewTypeAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{
public static final int ONE_ITEM = 1;
public static final int TWO_ITEM = 2;
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater mInflater = LayoutInflater.from(ViewTypeActivity.this);
RecyclerView.ViewHolder holder = null;
if(ONE_ITEM == viewType){
View v = mInflater.inflate(R.layout.item_linear,parent,false);
holder = new OneViewHolder(v);
}else{
View v = mInflater.inflate(R.layout.item_two,parent,false);
holder = new TwoViewHolder(v);
}
return holder;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if(holder instanceof OneViewHolder){
((OneViewHolder) holder).tv.setText(mDatas.get(position));
}else {
((TwoViewHolder) holder).tv1.setText(mDatas.get(position));
((TwoViewHolder) holder).tv2.setText(mDatas.get(position));
}
}
@Override
public int getItemViewType(int position) {
if(position % 3 == 0){
return TWO_ITEM;
}else{
return ONE_ITEM;
}
}
@Override
public int getItemCount() {
return mDatas.size();
}
class OneViewHolder extends RecyclerView.ViewHolder{
TextView tv;
public OneViewHolder(View itemView) {
super(itemView);
tv = (TextView) itemView.findViewById(R.id.adapter_linear_text);
}
}
class TwoViewHolder extends RecyclerView.ViewHolder{
TextView tv1,tv2;
public TwoViewHolder(View itemView) {
super(itemView);
tv1 = (TextView) itemView.findViewById(R.id.adapter_two_1);
tv2 = (TextView) itemView.findViewById(R.id.adapter_two_2);
}
}
}
}
两个XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="50dp"
android:orientation="horizontal">
<TextView
android:id="@+id/adapter_two_1"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:layout_marginRight="5dp"
android:background="#3FFF99"
android:gravity="center" />
<TextView
android:id="@+id/adapter_two_2"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_marginLeft="5dp"
android:layout_height="match_parent"
android:background="#3FFF99"
android:gravity="center" />
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/adapter_linear_text"
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#a9a8ff"
android:gravity="center"/>
间距的设定请看第一篇,效果图如下：
这里写图片描述
通过RecyclerView.Adapter设置多布局是非常方便的，而且大家可以发现当RecyclerView为LinearLayoutManager，我们可以通过viewType给RecyclerView来设置Header和Footer，如
public static final int HEADER = 1;
public static final int FOOTER = 2;
public static final int ITEM = 3;
@Override
public int getItemViewType(int position) {
if(position == 0){
return HEADER;
}else if(position == getItemCount() -1){
return FOOTER;
}else{
return ITEM;
}
}
@Override
public int getItemCount() {
return mDatas.size() + 2;//Header和Footer
}
但是当布局管理器为GridLayoutManager和StaggeredGridLayoutManager时就要不能这样去做了。
如何去加我会放在后面去写。
