xListView（联网判断）

最新推荐文章于 2017-11-10 14:20:12 发布

原创最新推荐文章于 2017-11-10 14:20:12 发布 · 297 阅读

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CC 4.0 BY-SA版权

本文介绍了一个具体的Android应用案例，展示了如何实现网络数据的获取、解析及显示过程。包括使用异步任务进行网络请求、JSON数据解析、自定义适配器实现数据与UI绑定等关键技术点。

1.MainActiv类

public class MainActivity extends AppCompatActivity implements XListView.IXListViewListener {

private XListView xLv;

private MyBaseAdapter adapter;

//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;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

xLv = (XListView) findViewById(R.id.xLv);

//设置是否可以上下拉加载

xLv.setPullLoadEnable(true);

xLv.setXListViewListener(this);

if(isOnline()) {

//有网，联网请求数据

getData();

}else{

//弹出提示对话框

showDialog();

}

private void showDialog(){

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

builder.setMessage("怎么可没网呢");

builder.setNegativeButton("不联网，",null);

builder.setPositiveButton("联网", 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();

}

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 getData(){

try {

getNetWorkData("http://apis.juhe.cn/cook/query.php?menu="+ URLEncoder.encode("西红柿","utf-8")+"&key=12345&pn="+pageIndex+"&rn=10");

} catch (Exception e) {

e.printStackTrace();

}

private void getNetWorkData(String url){

new AsyncTask(){

@Override

protected void onPostExecute(String s) {

super.onPostExecute(s);

if(s == null){

return;

}

Gson gson = new Gson();

MenuInfo menuInfo = gson.fromJson(s,MenuInfo.class);

List dataBeanList = menuInfo.getResult().getData();

if(adapter == null) {

//将数据绑定到适配上

adapter = new MyBaseAdapter(MainActivity.this, dataBeanList);

//将适配器上的数据映射到ListView

xLv.setAdapter(adapter);

}else{

adapter.loadMore(dataBeanList,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);

int code = connection.getResponseCode();

if(code == 200){

InputStream is = connection.getInputStream();

return StreamTools.readFromNetWork(is);

}

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

}.execute(url);

}

@Override

public void onRefresh() {

flag = true;

++pageIndex;

getData();

//停止下拉刷新

xLv.stopRefresh(true);

}

@Override

public void onLoadMore() {

Log.d("MainActivity", "上拉加载更多数据");

flag = false;

++pageIndex;

getData();

//停止加载更多

xLv.stopLoadMore();

}

2.Application类

public class MyApplication extends Application {

@Override

public void onCreate() {

super.onCreate();

String path = Environment.getExternalStorageDirect ory()+"1507DAccess";

File cacheDir = new File(path);

ImageLoaderConfiguration config = new ImageLoaderConfiguration .Builder(this)

.threadPriority(100)

.threadPoolSize(3)

.memoryCacheExtraOptions(200,200)

.memoryCacheSize(2 * 1024 * 1024)

.diskCache(new UnlimitedDiskCache(cacheDir))

.diskCacheFileNameGenerat or(new Md5FileNameGenerator())

.diskCacheSize(50 * 1024 * 1024)

.build();

ImageLoader.getInstance().init(config);

}

public static DisplayImageOptions getOptons(){

DisplayImageOptions options = new DisplayImageOptions.Builder()

.cacheInMemory(true)

.cacheOnDisk(true)

.showImageForEmptyUri(R.mipmap.ic_empty)

.showImageOnFail(R.mipmap.ic_error)

.showImageOnLoading(R.mipmap.loading)

.build();

return options;

}

3.适配器类

public class MyBaseAdapter extends BaseAdapter {

private Context context;

private List dataBeanList;

public MyBaseAdapter(Context context,List dataBeanList){

this.context=context;

this.dataBeanList = dataBeanList;

}

public void loadMore(List datas,boolean flag){

for (MenuInfo.ResultBean.DataBean dataBean : datas) {

//flag = true 代表下拉 false 上拉

if(flag){

dataBeanList.add(0,dataBean);

}else {

//将更多的数据添加到原来与适配器绑定的集合中去

dataBeanList.add(dataBean);

}

//刷新界面

notifyDataSetChanged();

}

@Override

public int getCount() {

return dataBeanList != null?dataBeanList.size() : 0;

}

@Override

public Object getItem(int position) {

return dataBeanList.get(position);

}

@Override

public long getItemId(int position) {

return position;

}

@Override

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

//填充布局

if(convertView == null){

convertView = convertView.inflate(context,R.layout.item,null);

}

ImageView ivIcon = (ImageView) convertView.findViewById(R.id.ivIcon);

TextView tvContent = (TextView) convertView.findViewById(R.id.tvContent);

//设置文本信息

tvContent.setText(dataBeanList.get(position).getTitle());

//加载图片

ImageLoader.getInstance().displayImage(dataBeanList.get(position).getAlbums().get(0),ivIcon,MyApplication.getOptons());

return convertView;

}

4.工具类

5.Json串类

6.访问网络、读取内存权限