Is there开发者_开发百科 an Android Intent ACTION_XXX that notifies me when an Internet Connection is available?

I want to instantiate a BroadcastReceiver that notifies my application when a user enables Internet Connection (by wifi, by GSM, etc.)

Could anyone help me?

<receiver android:name=".YOURRECEIVER">
   <intent-filter>
      <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
   </intent-filter>
</receiver>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

Accepted answer is correct. I only add Receiver code for completion:

public class NetworkStateReceiver extends BroadcastReceiver {
    public void onReceive(Context context, Intent intent) {
     Log.d("app","Network connectivity change");
     if(intent.getExtras()!=null) {
        NetworkInfo ni=(NetworkInfo) intent.getExtras().get(ConnectivityManager.EXTRA_NETWORK_INFO);
        if(ni!=null && ni.getState()==NetworkInfo.State.CONNECTED) {
            Log.i("app","Network "+ni.getTypeName()+" connected");
        } else if(intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY,Boolean.FALSE)) {
            Log.d("app","There's no network connectivity");
        }
   }
}

Update to @lujop answer:

public class NetworkStateReceiver extends BroadcastReceiver {
    private static final String TAG = "NetworkStateReceiver";

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

        Log.d(TAG, "Network connectivity change");

        if (intent.getExtras() != null) {
            final ConnectivityManager connectivityManager = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
            final NetworkInfo ni = connectivityManager.getActiveNetworkInfo();

            if (ni != null && ni.isConnectedOrConnecting()) {
                Log.i(TAG, "Network " + ni.getTypeName() + " connected");
            } else if (intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, Boolean.FALSE)) {
                Log.d(TAG, "There's no network connectivity");
            }
        }
    }
}

MyReceiver.java

public class MyReceiver extends BroadcastReceiver{

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

        if(isConnected(context)) Toast.makeText(context, "Connected.", Toast.LENGTH_LONG).show();
        else Toast.makeText(context, "Lost connect.", Toast.LENGTH_LONG).show();
    }

    public boolean isConnected(Context context) {
        ConnectivityManager cm =
                (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        boolean isConnected = activeNetwork != null &&
                              activeNetwork.isConnected();
        return isConnected;
    }
}

AndroidManifest.xml

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

UPDATE

If your app targets API level 26 or higher, you cannot use the manifest to declare a receiver for implicit broadcasts (broadcasts that do not target your app specifically), except for a few implicit broadcasts that are exempted from that restriction. In most cases, you can use scheduled jobs instead.

usage connection = MyReceiver()

// onCreate - onDestroy, onResume - onPause depends on you
override fun onStart() {
    super.onStart()
    registerReceiver(connection, IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION))
  }

override fun onStop() {
    super.onStop()
    // remember unregister to avoid leak
    unregisterReceiver(connection)
  }

UPDATE 2

CONNECTIVITY_ACTION This constant was deprecated in API level 28. apps should use the more versatile requestNetwork(NetworkRequest, PendingIntent), registerNetworkCallback(NetworkRequest, PendingIntent) or registerDefaultNetworkCallback(ConnectivityManager.NetworkCallback) functions instead for faster and more detailed updates about the network changes they care about.

because it added in API level 22, so above code will work fine on all versions of android

The missing part of all answers is a reminder to register for that action:

IntentFilter filter = new IntentFilter();
filter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
registerReceiver(your_receiver, filter);

This code will work (in all versions) as the manifest registration will not work for 7+(API 25 and above) devices see this link.

private void foo(){
    registerReceiver(connectionBroadcastReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
}

private BroadcastReceiver connectionBroadcastReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent == null || intent.getExtras() == null)
           return;

        ConnectivityManager cm = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = cm.getActiveNetworkInfo();
        if (networkInfo != null && networkInfo.getState() == NetworkInfo.State.CONNECTED) {  
            // connected
        } 
    }
};

I'm using broadcast to check the connection every time. Create a class for connection info.

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


public class ConnectivityStatus extends ContextWrapper{

    public ConnectivityStatus(Context base) {
        super(base);
    }

    public static boolean isConnected(Context context){

        ConnectivityManager manager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo connection = manager.getActiveNetworkInfo();
        if (connection != null && connection.isConnectedOrConnecting()){
            return true;
        }
        return false;
    }
}

Apply code into your Activity:

 private BroadcastReceiver receiver = new BroadcastReceiver() {
 @Override
 public void onReceive(Context context, Intent intent) {
        if(!ConnectivityStatus.isConnected(getContext())){
            // no connection
        }else {
            // connected
        }
    }
 };

Register broadcast in your activity's onCreate() method:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.your_layout);
    your_activity_context.registerReceiver(receiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
    ..
    ...
    ....
  }

Don't forget to unregistered/register on Activity cycle:

@Override
protected void onResume() {
    super.onResume();
    your_activity_context.registerReceiver(receiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));

}

@Override
protected void onPause() {
    super.onPause();
    your_activity_context.unregisterReceiver(receiver);

}

Continuing meow mwo's Answer

you can enable/disable the receiver by:

enable

 ComponentName receiver = new ComponentName(MainActivity.this, MyReceiver.class);
       PackageManager pm = this.getPackageManager();
       pm.setComponentEnabledSetting(receiver,
               PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
               PackageManager.DONT_KILL_APP);
       Toast.makeText(this, "Disabled broadcst receiver", Toast.LENGTH_SHORT).show();
   }

disable

ComponentName receiver = new ComponentName(MainActivity.this, MyReceiver.class);
       PackageManager pm = this.getPackageManager();
       pm.setComponentEnabledSetting(receiver,
               PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
               PackageManager.DONT_KILL_APP);
       Toast.makeText(this, "Enabled broadcast receiver", Toast.LENGTH_SHORT).show();
   }

where, the same can be called in an Intent or in onCreate

NetworkInfo.isConnected() is unreliable method to test for internet status, it will return true when there is a network connection even though it may have no internet access (ex. wifi with no internet). A more reliable approach would be to use ping with a CONNECTIVITY_ACTION BroadcastReceiver:

private void registerInternetReceiver()
{
    if (this.internetReceiver != null) return;
    this.internetReceiver = new BroadcastReceiver()
    {
        @Override
        public void onReceive (Context context, Intent intent)
        {
            if (isInternetAvailable()) Log.i ("Tag", "internet status online");
            else Log.i ("Tag", "internet status offline");
        }
    };
    IntentFilter filter = new IntentFilter();
    filter.addAction (ConnectivityManager.CONNECTIVITY_ACTION);
    registerReceiver (internetReceiver, filter);
}

private boolean isInternetAvailable()
{
    try
    {
        return (Runtime.getRuntime().exec ("ping -c 1 google.com").waitFor() == 0);
    }
    catch (Exception ex)
    {
        ex.printStackTrace();
    }
    return false;
}

**Also worked on above Android 7.0**

// AndroidManifest.xml

 <service
            android:name=".NetworkSchedulerService"
            android:exported="true"
            android:permission="android.permission.BIND_JOB_SERVICE"/>


// MyApplication.java           

import  android.app.Application;
import android.app.job.JobInfo;
import android.app.job.JobScheduler;
import android.content.ComponentName;
import android.content.Context;
public class MyApplication extends Application {

    private static Context context;

    public static Context getContext() {
        return context;
    }

    public static final String TAG = MyApplication.class.getSimpleName();

    private static MyApplication mInstance;


    @Override
    public void onCreate() {
        super.onCreate();
        context = getApplicationContext();
        mInstance = this;
        scheduleJob();
    }

    public static synchronized MyApplication getInstance() {
        return mInstance;
    }

    private void scheduleJob()
    {
        JobInfo myJob = new JobInfo.Builder(0, new ComponentName(this, NetworkSchedulerService.class))
                .setRequiresCharging(true)
                .setMinimumLatency(1000)
                .setOverrideDeadline(2000)
                .setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY)
                .setPersisted(true)
                .build();

        JobScheduler jobScheduler = (JobScheduler) getSystemService(Context.JOB_SCHEDULER_SERVICE);
        assert jobScheduler != null;
        jobScheduler.schedule(myJob);
    }
}   


// Constants.java   

public class Constants {
    public static final String CONNECT_TO_WIFI = "WIFI";
    public static final String CONNECT_TO_MOBILE = "MOBILE";
    public static final String NOT_CONNECT = "NOT_CONNECT";
    public final static String CONNECTIVITY_ACTION = "android.net.conn.CONNECTIVITY_CHANGE";
}


// LiveConnectivityReceiver.java    

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

public class LiveConnectivityReceiver extends BroadcastReceiver {

    private MConnectivityReceiver mConnectivityReceiver;
    LiveConnectivityReceiver(MConnectivityReceiver listener) {
        mConnectivityReceiver = listener;
    }


    @Override
    public void onReceive(Context context, Intent intent) {
        mConnectivityReceiver.onNetworkConnectionChanged(isConnected(context));

    }

    public static boolean isConnected(Context context) {
        ConnectivityManager cm = (ConnectivityManager)
                context.getSystemService(Context.CONNECTIVITY_SERVICE);
        assert cm != null;
        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        return activeNetwork != null && activeNetwork.isConnectedOrConnecting();
    }

    public interface MConnectivityReceiver {
        void onNetworkConnectionChanged(boolean isConnected);
    }
}   


// MainActivity.java    

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private BroadcastReceiver mReceiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }


    @Override
    protected void onStop() {
        stopService(new Intent(this, NetworkSchedulerService.class));
        super.onStop();
    }

    @Override
    protected void onStart() {
        super.onStart();
        startService( new Intent(this, NetworkSchedulerService.class));
    }


    @Override
    protected void onPause() {
        super.onPause();
        this.unregisterReceiver(this.mReceiver);
    }

    @Override
    protected void onResume() {
        super.onResume();
        IntentFilter intentFilter = new IntentFilter("android.intent.action.MAIN");
        mReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                boolean isConnection = intent.getBooleanExtra("VALUE", false);
                if (!isConnection) {
                    Toast.makeText(context, "No Internet Connection", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(context, "Back to online", Toast.LENGTH_SHORT).show();
                }
            }
        };
        this.registerReceiver(mReceiver, intentFilter);
    }
}   


// NetworkSchedulerService.java 


import android.app.job.JobParameters;
import android.app.job.JobService;
import android.content.Intent;
import android.content.IntentFilter;

public class NetworkSchedulerService extends JobService implements LiveConnectivityReceiver.ConnectivityReceiverListener 
{

    private LiveConnectivityReceiver mLiveConnectivityReceiver;

    @Override
    public void onCreate()
    {
        super.onCreate();
        mLiveConnectivityReceiver = new LiveConnectivityReceiver(this);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        return START_NOT_STICKY;
    }

    @Override
    public boolean onStartJob(JobParameters params) {
        registerReceiver(mLiveConnectivityReceiver, new IntentFilter(Constants.CONNECTIVITY_ACTION));
        return true;
    }

    @Override
    public boolean onStopJob(JobParameters params) {
        unregisterReceiver(mLiveConnectivityReceiver);
        return true;
    }

    @Override
    public void onNetworkConnectionChanged(boolean isConnected)
    {
        Intent broadcastedIntent=new Intent("android.intent.action.MAIN");
        broadcastedIntent.putExtra("VALUE", isConnected);
        sendBroadcast(broadcastedIntent);
    }
}

From Android 7++, @fedj's answer will not work but you can register the broadcast receiver programmatically.

Apps targeting Android 7.0 (API level 24) and higher do not receive CONNECTIVITY_ACTION broadcasts if they declare the broadcast receiver in their manifest. Apps will still receive CONNECTIVITY_ACTION broadcasts if they register their BroadcastReceiver with Context.registerReceiver() and that context is still valid.

I would read the docs updated for nougat + , because intent is deprecated due to the # of devices, network info alone is not sufficient. I would use connectivity manager ( connectivity action, add variables there) commands and vars there, because most has changed in the last year alone, and on for testing, enable cell data always active, verbose logging and aggressive handover, use wlan filter if needed:

https://developer.android.com/reference/android/net/ConnectivityManager.html#CONNECTIVITY_ACTION

**You can put this line of code on Helper Methods and call it when you want to check internet connection **

public static class InternetState {
    static ConnectivityManager cm;

    static public boolean isConnected(Context context) {
        try {
            cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        } catch (NullPointerException e) {

        }

        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        boolean isConnected = activeNetwork != null && activeNetwork.isConnectedOrConnecting();
        return isConnected;
    }
}