上拉与下拉加载判断是否联网

最新推荐文章于 2024-09-14 16:54:29 发布

原创最新推荐文章于 2024-09-14 16:54:29 发布 · 412 阅读

0 ·

CC 4.0 BY-SA版权

本文介绍了一个使用XListView实现的分页加载案例，详细展示了如何配置图片加载选项、设置XListView监听器、处理网络请求及数据解析过程，并实现了数据的上拉下拉刷新功能。

//初始化DisplayImageOptions

static {

options = new DisplayImageOptions.Builder()

.showImageOnFail(R.mipmap.ic_error)

.showImageForEmptyUri(R.mipmap.ic_empty)

.showImageOnLoading(R.mipmap.loading)

.build();

}

private static DisplayImageOptions options;

private XListView xListView;

private List list;

//定义一个页码变量记录用户刷新到第几页了

private int pageIndex = 1;

//定义一个变量去记录用户操作行为(例如：上拉、下拉)

private boolean flag;

private MyAdapter myAdapter;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

//找到控件

xListView = (XListView) findViewById(R.id.xlist);

//设置是否可以上下拉加载

xListView.setPullLoadEnable(true);

//让主类去implements实现XListView.IXListViewListener

xListView.setXListViewListener(this);

//调用加载网络资源的方法

if(isOnline()){

//有网，联网请求数据

init();

}else {

//弹出提示对话框

showDialog();

}

//加载网络资源

public void init(){

try {

readNetContent("http://apis.juhe.cn/cook/query.php?key=e3c3dd5597dd875ff29c665a25b740251&pn="+pageIndex+"&rn=8&menu="+ URLEncoder.encode("西红柿","utf-8")+"");

} catch (Exception e) {

e.printStackTrace();

}

//加载网络资源

public void readNetContent(String path){

new AsyncTask(){

@Override

protected void onPostExecute(String s) {

if(s == null){

return;

}

Gson gson = new Gson();

BigMenu bigMenu = gson.fromJson(s, BigMenu.class);

list = bigMenu.getResult().getData();

//将数据绑定到适配上

if(myAdapter ==null){

myAdapter = new MyAdapter(list);

xListView.setAdapter(myAdapter);

}else {

myAdapter.loadMore(list,flag);

}

@Override

protected String doInBackground(String... params) {

try {

URL url = new URL(params[0]);

HttpURLConnection connection = (HttpURLConnection) url.openConnection();

connection.setRequestMethod("GET");

connection.setConnectTimeout(5000);

connection.setReadTimeout(5000);

if(connection.getResponseCode() == 200){

InputStream is = connection.getInputStream();

String result = readStream(is);

return result;

}

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

}.execute(path);

}

//xlistview的适配器

class MyAdapter extends BaseAdapter {

private final List bigList;

public MyAdapter(List list) {

this.bigList = list;

}

//定义一个方法不断获取新的资源并把新的资源添加到原有的数据集合

//并判断是上拉还是下拉保证最新的资源在用户眼前

public void loadMore(List dataBeen, boolean flag){

for (BigMenu.ResultBean.DataBean da:dataBeen) {

if(flag == true){

bigList.add(0,da);

}else {

bigList.add(da);

}

//刷新适配器

notifyDataSetChanged();

}

@Override

public int getCount() {

return bigList.size();

}

@Override

public Object getItem(int position) {

return bigList.get(position);

}

@Override

public long getItemId(int position) {

return position;

}

@Override

public View getView(int position, View convertView, ViewGroup parent) {

ViewHolder viewHolder;

//判断从converview不为空

if(convertView == null){

//装换布局

convertView = View.inflate(MainActivity.this,R.layout.item_main,null);

viewHolder = new ViewHolder();

//找到控件

viewHolder.title = (TextView) convertView.findViewById(R.id.titleName);

viewHolder.pic = (ImageView) convertView.findViewById(R.id.pic);

convertView.setTag(viewHolder);

}else {

viewHolder = (ViewHolder) convertView.getTag();

}

//为控件赋值

viewHolder.title.setText(bigList.get(position).getTitle());

ImageLoader.getInstance().displayImage(bigList.get(position).getSteps().get(0).getImg(),viewHolder.pic,options);

return convertView;

}

//viewholder类

class ViewHolder{

private TextView title;

private ImageView pic;

}

//装换字符流的方法

public String readStream(InputStream is){

try {

ByteArrayOutputStream baos = new ByteArrayOutputStream();

int len;

byte[] bytes = new byte[1024];

while((len = is.read(bytes))>0){

baos.write(bytes,0,len);

}

return baos.toString();

} catch (IOException e) {

e.printStackTrace();

}

return null;

}

//下拉时会被执行的方法

@Override

public void onRefresh() {

pageIndex++;

flag=true;

//改变加载的页数再次获取资源

init();

//停止下拉刷新

xListView.stopRefresh(true);

}

//上拉时会被执行的方法

@Override

public void onLoadMore() {

pageIndex++;

flag=false;

//改变加载的页数再次获取资源

init();

//停止加载更多

xListView.stopLoadMore();

}

public boolean isOnline() {

//得到一个连接管理者

ConnectivityManager connMgr = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);

//得到联网信息

NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

//判断设备是否联网

return (networkInfo != null && networkInfo.isConnected());

}

private void showDialog(){

AlertDialog.Builder builder = new AlertDialog.Builder(this);

builder.setMessage("网络请求失败");

builder.setNegativeButton("取消",null);

builder.setPositiveButton("查看网络设置", new DialogInterface.OnClickListener() {

@Override

public void onClick(DialogInterface dialog, int which) {

//跳转网络设置界面

startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));

}

});

builder.create().show();

}

重要权限：<</span>uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>