Xlistview请求数据上拉刷新 下拉加载

在MainActivity 中的代码如下
public class MainActivity extends AppCompatActivity {

private XListView xListView;
private List<JsonBean.ResultBean.DataBean> daat;
private MyAdapter adapter;
private String str = "http://apis.juhe.cn/cook/query?key=433edc0880b0a093db31bb80a7b87a72&menu=%E7%82%92%E9%9D%A2";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //2找控件
    xListView = findViewById(R.id.xListView);
    //3启用或禁用上拉加载
    xListView.setPullLoadEnable(true);
    //4注册XListViewListener接口
    xListView.setXListViewListener(new XListView.IXListViewListener() {
        @Override
        public void onRefresh() {
            //刷新回调
            HttpUtils.httpAsynTask(str, new HttpUtils.CallBackString() {
                @Override
                public void getData(String s) {
                    Gson gson = new Gson();
                    JsonBean bean = gson.fromJson(s, JsonBean.class);
                    daat = bean.getResult().getData();
                    adapter = new MyAdapter(MainActivity.this, daat);
                    xListView.setAdapter(adapter);
                    onLoad();
                }
            });
        }

        @Override
        public void onLoadMore() {
            //9上拉
            //加载调用的方法
            HttpUtils.httpAsynTask(str, new HttpUtils.CallBackString() {
                @Override
                public void getData(String s) {
                    Gson gson = new Gson();
                    JsonBean bean = gson.fromJson(s, JsonBean.class);
                    // List<JsonBean.ResultBean.DataBean> list= bean.getResult().getData();
                    List<JsonBean.ResultBean.DataBean> list = bean.getResult().getData();
                    //把数据放进集合中
                    daat.addAll(list);
                    //刷新数据
                    adapter.notifyDataSetChanged();
                    onLoad();
                }
            });
        }
    });
    //5数据
    HttpUtils.httpAsynTask(str, new HttpUtils.CallBackString() {
        @Override
        public void getData(String s) {
            //6解析
            Gson gson = new Gson();
            JsonBean bean = gson.fromJson(s, JsonBean.class);
            daat = bean.getResult().getData();
            //7适配器
            adapter = new MyAdapter(MainActivity.this, daat);
            //8设置适配器
            xListView.setAdapter(adapter);
            //有效果
        }
    });
}

private void onLoad() {
    //停止加载更多，重置头视图
    xListView.stopRefresh();
    //停止加载更多，重置脚视图
    xListView.stopLoadMore();
    //设置刷新时间
    xListView.setRefreshTime("刚刚刷新了");
}

}
//HTTP中接口回调以及get请求
public class HttpUtils {
public static void httpAsynTask(String strUrl, final CallBackString backString){
new AsyncTask<String,Integer,String>(){
@Override
protected String doInBackground(String… strings) {
return httpGet(strings[0]);
}

@Override
protected void onPostExecute(String s) {
    super.onPostExecute(s);
    backString.getData(s);
}

}.execute(strUrl);

}
public interface CallBackString{
void getData(String s);
}
public static String httpGet(String strUrl){
try {
URL url=new URL(strUrl);
HttpURLConnection connection= (HttpURLConnection) url.openConnection();
connection.setRequestMethod(“GET”);
connection.setConnectTimeout(5000);
connection.setReadTimeout(5000);
InputStream stream=connection.getInputStream();
BufferedReader reader=new BufferedReader(new InputStreamReader(stream));
//拼接数据
StringBuilder builder=new StringBuilder();
String str="";
while ((str=reader.readLine())!=null){
builder.append(str);
}
connection.disconnect();
return builder.toString();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}