android how to get indicate when the internet connection is lost?

问题

I'm developing an android application and I want to get a notification when the internet (wifi or packet data connection) connection is lost. On my approach I can get the status of the connection as:

private boolean isNetworkAvailable() {
ConnectivityManager connectivityManager 
      = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
return activeNetworkInfo != null && activeNetworkInfo.isConnected();
}

while having this in the Manifest:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

How could I be notified automatically when the connection is lost?

回答1:

For WIFI you could register a broadcast receiver as:

IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION);
registerReceiver(broadcastReceiver, intentFilter);

You can also register the receiver in the Manifest.

Then in your receiver:

@Override
public void onReceive(Context context, Intent intent) {
    final String action = intent.getAction();
    if (action.equals(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION)) {
        if (intent.getBooleanExtra(WifiManager.EXTRA_SUPPLICANT_CONNECTED, false)){
            //do stuff
        } else {
            // wifi connection was lost
        }
    }
}

For any type of data connection listeners you could use the following receiver registered as:

<receiver android:name=".receiver.ConnectivityReceiver">
    <intent-filter>
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
        <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
    </intent-filter>
</receiver>

and the in your ConnectivityReceiver:

public class ConnectivityReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
    }
}

In the onReceive method you could check if you have internet connectivity or not using this developer article.

回答2:

use following code:

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import classes.NetworkUtil;

public class NetworkChangeReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(final Context context, final Intent intent) {

            boolean IsConnected = NetworkUtil.getConnectivityStatusString(context);
           // Toast in here, you can retrieve other value like String from NetworkUtil
           // but you need some change in NetworkUtil Class
        }
    }

and NetworkUtil is:

package classes;

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

public class NetworkUtil {

    public static int TYPE_WIFI = 1;
    public static int TYPE_MOBILE = 2;
    public static int TYPE_NOT_CONNECTED = 0;


    public static int getConnectivityStatus(Context context) {
        ConnectivityManager cm = (ConnectivityManager) context
                .getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        if (null != activeNetwork) {
            if(activeNetwork.getType() == ConnectivityManager.TYPE_WIFI)
                return TYPE_WIFI;

            if(activeNetwork.getType() == ConnectivityManager.TYPE_MOBILE)
                return TYPE_MOBILE;
        } 
        return TYPE_NOT_CONNECTED;
    }

    public static boolean getConnectivityStatusString(Context context) {
        int conn = NetworkUtil.getConnectivityStatus(context);
        boolean status = false ;
        if (conn == NetworkUtil.TYPE_WIFI) {
            status = true;
        } else if (conn == NetworkUtil.TYPE_MOBILE) {
            status = true; 
        } else if (conn == NetworkUtil.TYPE_NOT_CONNECTED) {
            status = false;
        }
        return status;
    }
}

and in manifest file:

 <receiver
            android:name="receiver.NetworkChangeReceiver" >
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            </intent-filter>
        </receiver>

and this permission:

 <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

回答3:

You need to set up a broadcast receiver.

Add these as intent filters.

            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
                <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
            </intent-filter>

回答4:

You should use BroadcastReceivers for your requirement. Create a BroadcastReceiver which listen for network changes.

Incase of any change in the network it will automatically fire the event and you can perform your operations regarding it.

来源：https://stackoverflow.com/questions/21226776/android-how-to-get-indicate-when-the-internet-connection-is-lost