RecycleView仿Grifview 左右滑动并实现右滑至最右边加载更多

package com.zaa.recycleview;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
ArrayList<String> datas=new ArrayList<>();
private RecyclerView recyclerView;

private GridAdapter adapter;
int start = 0 ;
int limit =20; //每次加载数据量
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = (RecyclerView) findViewById(R.id.recycleview);
GridLayoutManager manager = new GridLayoutManager(this,2);
manager.setOrientation(LinearLayoutManager.HORIZONTAL);
recyclerView.setLayoutManager(manager);
recyclerView.addItemDecoration(new SpacesItemDecoration(20));
adapter = new GridAdapter();
recyclerView.setAdapter(adapter);
loadData();
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
Log.e("infoo","newState:"+newState+"---"+recyclerView.computeHorizontalScrollExtent()+"----"+recyclerView.computeHorizontalScrollOffset()+"--"+recyclerView.computeHorizontalScrollRange());
int se=recyclerView.computeHorizontalScrollExtent();
int so=recyclerView.computeHorizontalScrollOffset();
int sr=recyclerView.computeHorizontalScrollRange();
if (newState == 0 && se + so == sr) {
if (datas.size() == 100) {    //设置加载上限
Toast.makeText(getApplicationContext(),"数据已经加载完毕",Toast.LENGTH_SHORT).show();
return;
}
start+=limit;
loadData();
}
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
}
});
}
private void loadData(){
for (int i = start; i < limit+start; i++) {
datas.add("测试数据"+i);
}
adapter.notifyDataSetChanged();
}
class GridAdapter extends RecyclerView.Adapter<ViewHolder> {
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = View.inflate(parent.getContext(), R.layout.item_grid, null);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(final ViewHolder holder, final int position) {

holder.textView.setText(datas.get(position));
}
@Override
public int getItemCount() {
return datas.size();
}
}
class ViewHolder extends RecyclerView.ViewHolder {
TextView textView;
public ViewHolder(View itemView) {
super(itemView);
textView= (TextView) itemView.findViewById(R.id.tvContent);
}
}
}