xlistview 下拉刷新，上拉加载

//MainActivity

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity---";
    //?keywords=笔记本&page=1
    private static String goods_url = "https://www.zhaoapi.cn/product/searchProducts";
    private XListView xListView;
    private int page = 1;
    List<GoodsBean.DataBean> list = new ArrayList<>();
    private MyAdapter myAdapter;
    private String keyword;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //初始化界面
        initViews();
        //通过网络获取数据
        getDataFromNet();

    }

    private void getDataFromNet() {
        HttpUtils httpUtils = HttpUtils.getInstance();
        try {
            keyword = URLEncoder.encode("笔记本", "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        String url = goods_url + "?source=android&keywords=" + keyword + "&page=" + page;
        Log.d(TAG, "getDataFromNet: " + url);
        httpUtils.get(url);
        httpUtils.setHttpUtilsListener(new HttpUtils.HttpUtilListener() {
            @Override
            public void getSuccess(String json) {
                Gson gson = new Gson();
                GoodsBean goodsBean = gson.fromJson(json, GoodsBean.class);
                List<GoodsBean.DataBean> list1 = goodsBean.getData();

                //设置适配器
                if (page == 1) {
                    list.clear();
                }
                list.addAll(list1);

                myAdapter.notifyDataSetChanged();
                //记得让头布局或者脚布局收回
                if (page == 1) {
                    xListView.stopRefresh();
                } else {
                    xListView.stopLoadMore();
                }
            }

            @Override
            public void getError(String error) {

            }
        });
    }

    private void initViews() {
        xListView = findViewById(R.id.xlistview);
        //xListView的使用
        xListView.setPullRefreshEnable(true);//设置可以刷新
        xListView.setPullLoadEnable(true);//设置可以上拉
        xListView.setXListViewListener(new XListView.IXListViewListener() {
            @Override
            public void onRefresh() {
                //当刷新的时候回调
                page = 1;
                getDataFromNet();
            }

            @Override
            public void onLoadMore() {
                //当上拉加载的时候回调
                page++;
                getDataFromNet();

            }
        });//设置监听
        //先创建适配器，方便以后刷新，注意，不要频繁的new Adapter
        myAdapter = new MyAdapter(MainActivity.this, list);
        xListView.setAdapter(myAdapter);
    }
}

//HttpUtils

public class HttpUtils {
    private static final String TAG = "HttpUtils---";
    private MyHandler myHandler = new MyHandler();
    private static final int SUCCESS = 0;
    private static final int ERROR = 1;

    //单利
    private static HttpUtils httpUtils = new HttpUtils();
    private HttpUtilListener httpUtilsListener;

    private HttpUtils() {
    }//构造方法私有化

    public static HttpUtils getInstance() {
        if (httpUtils == null) {
            httpUtils = new HttpUtils();
        }
        return httpUtils;
    }

    //封装get
    public void get(final String url) {
        new Thread() {
            @Override
            public void run() {
                try {
                    URL u = new URL(url);
                    HttpURLConnection connection = (HttpURLConnection) u.openConnection();
                    connection.setConnectTimeout(3000);
                    if (connection.getResponseCode() == 200) {
                        InputStream inputStream = connection.getInputStream();
                        String json = inputStream2String(inputStream);
                        //发送数据
                        Message message = myHandler.obtainMessage();
                        message.what = SUCCESS;
                        message.obj = json;
                        myHandler.sendMessage(message);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                    Message message = myHandler.obtainMessage();
                    message.what = ERROR;
                    message.obj = e.getMessage();
                    myHandler.sendMessage(message);
                }
            }
        }.start();
    }

    class MyHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case SUCCESS:
                    //成功
                    String json = (String) msg.obj;
                    Log.d(TAG, "handleMessage: " + json);
                    httpUtilsListener.getSuccess(json);
                    break;
                case ERROR:
                    //失败
                    String error = (String) msg.obj;
                    Log.d(TAG, "handleMessage: " + error);
                    httpUtilsListener.getError(error);
                    break;
            }
        }
    }

    //1.定义接口
    public interface HttpUtilListener {
        void getSuccess(String json);

        void getError(String error);
    }

    //2.外部访问的方法
    public void setHttpUtilsListener(HttpUtilListener httpUtilsListener) {
        this.httpUtilsListener = httpUtilsListener;
    }

    public String inputStream2String(InputStream inputStream) {
        int len = 0;
        byte[] butter = new byte[1024];
        StringBuffer stringBuffer = new StringBuffer();
        try {

            while ((len = inputStream.read(butter)) != -1) {
                String s = new String(butter, 0, len);
                stringBuffer.append(s);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }


        return stringBuffer.toString();
    }


}