判断有网没网

新建一个类

package com.example.rk1214;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public class NeUtil {

public static boolean hasNetwork(Context context){
    //创建连接管理器
    ConnectivityManager cm= (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    //获得最新流动状态
    NetworkInfo activeNetworkInfo = cm.getActiveNetworkInfo();
    return activeNetworkInfo!=null&&activeNetworkInfo.isAvailable();
}

}

判断有网没网
private void indata(int num) {
if (NeUtil.hasNetwork(getActivity())==false){
Toast.makeText(getActivity(),“联网失败”,Toast.LENGTH_SHORT).show();
list=dao.select();
//适配器里面的添加集合方法
madapter.setdata(list);
return;
}else if (NeUtil.hasNetwork(getActivity())true){
new AsyncTask<String, View, List<Bean.DataBean>>() {
@Override
protected List<Bean.DataBean> doInBackground(String… strings) {
try {
URL url = new URL(strings[0]);
HttpURLConnection httpURLConnection=(HttpURLConnection)url.openConnection();
httpURLConnection.setRequestMethod(“GET”);
httpURLConnection.setConnectTimeout(5000);
httpURLConnection.setReadTimeout(5000);
int responseCode = httpURLConnection.getResponseCode();
if (responseCode200){
String s = s2(httpURLConnection.getInputStream());
Gson gson = new Gson();
bean = gson.fromJson(s, Bean.class);
return bean.getData();
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}

            @Override
            protected void onPostExecute(List<Bean.DataBean> dataBeans) {
                dao.addall(dataBeans);
                list.addAll(dataBeans);
                madapter.notifyDataSetChanged();
            }
        }.execute(url+num);
    }

}


private String s2(InputStream inputStream) {
    StringBuilder stringBuilder = new StringBuilder();
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
    try {
        for (String temp=bufferedReader.readLine();temp!=null;temp=bufferedReader.readLine()){
              stringBuilder.append(temp);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    return stringBuilder.toString();
}

}