我正在开发一个用于检查互联网连接的android广播接收器。
问题是我的广播接收器被调用了两次。我希望它只在网络可用时被调用。如果它不可用，我不想被通知。
这是广播接收机
public class NetworkChangeReceiver extends BroadcastReceiver {
@Override
public void onReceive(final Context context, final Intent intent) {
final ConnectivityManager connMgr = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
final android.net.NetworkInfo wifi = connMgr
.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
final android.net.NetworkInfo mobile = connMgr
.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
if (wifi.isAvailable() || mobile.isAvailable()) {
// Do something
Log.d("Network Available ", "Flag No 1");
}
}
}
这是manifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.broadcastreceiverforinternetconnection"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<receiver android:name=".NetworkChangeReceiver" >
<intent-filter>
<action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
<action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
</intent-filter>
</receiver>
</application>
</manifest>
public class NetworkChangeReceiver extends BroadcastReceiver {
@Override
public void onReceive(final Context context, final Intent intent) {
if (checkInternet(context)) {
Toast.makeText(context, "Network Available Do operations", Toast.LENGTH_LONG).show();
}
}
boolean checkInternet(Context context) {
ServiceManager serviceManager = new ServiceManager(context);
return serviceManager.isNetworkAvailable()
}
}
ServiceManager.java
public class ServiceManager {
Context context;
public ServiceManager(Context base) {
context = base;
}
public boolean isNetworkAvailable() {
ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = cm.getActiveNetworkInfo();
return networkInfo != null && networkInfo.isConnected();
}
}
权限:
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
public static boolean isNetworkAvailable(Context context) {
boolean isMobile = false, isWifi = false;
NetworkInfo[] infoAvailableNetworks = getConnectivityManagerInstance(
context).getAllNetworkInfo();
if (infoAvailableNetworks != null) {
for (NetworkInfo network : infoAvailableNetworks) {
if (network.getType() == ConnectivityManager.TYPE_WIFI) {
if (network.isConnected() && network.isAvailable())
isWifi = true;
}
if (network.getType() == ConnectivityManager.TYPE_MOBILE) {
if (network.isConnected() && network.isAvailable())
isMobile = true;
}
}
}
return isMobile || isWifi;
}
/* You can write such method somewhere in utility class and call it NetworkChangeReceiver like below */
public class NetworkChangedReceiver extends BroadcastReceiver
{
@Override
public void onReceive(Context context, Intent intent) {
if (isNetworkAvailable(context))
{
Toast.makeText(context, "Network Available Do operations",Toast.LENGTH_LONG).show();
}
}
}
只有当网络状态变为已连接而不是已断开时，才会调用上述广播接收器。
到2022年，上述BroadcastReceiver方法都将失效。由于Android 7.0的限制，BroadcastReceiver方法将不再工作。检查互联网是否可用的最新和最简单的方法是使用以下代码。(Android 12测试)
val networkRequest = NetworkRequest.Builder()
.addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
.addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
.addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
.build()
private val networkCallback = object : ConnectivityManager.NetworkCallback() {
// network is available for use
override fun onAvailable(network: Network) {
super.onAvailable(network)
}
// Network capabilities have changed for the network
override fun onCapabilitiesChanged(
network: Network,
networkCapabilities: NetworkCapabilities
) {
super.onCapabilitiesChanged(network, networkCapabilities)
val unmetered = networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_METERED)
}
// lost network connection
override fun onLost(network: Network) {
super.onLost(network)
}
}
val connectivityManager = getSystemService(ConnectivityManager::class.java) as ConnectivityManager
connectivityManager.requestNetwork(networkRequest, networkCallback
将这段代码放在一个函数中，并在activity/fragment的onCreate()中调用它。在onAvailable()和onLost()函数中，每当互联网连接或断开连接时，您都会收到通知。与此同时，您可以使用liveData或任何您喜欢的方式在其他活动/片段中广播这些更新。
官方文档链接:https://developer.android.com/training/monitoring-device-state/connectivity-status-type
警告:为android.net.conn.CONNECTIVITY_CHANGE声明一个broadcastreceiver对于目标为N或更高的应用程序是不建议使用的。一般来说，应用程序不应该依赖于这个广播，而是使用JobScheduler或GCMNetworkManager。
由于CONNECTIVITY_CHANGE已弃用，那么我们应该使用另一种方式来做相同的事情
接下来的NetworkConnectionLiveData将处理所有的OS Version，直到现在，如果目标SDK小于Build.VERSION_CODES。棒棒糖，那么只有我们可以使用broadcastReceiver
最好的部分是这个类使用LiveData，所以不需要注册任何接收器使用LiveData，它将处理所有的事情
class NetworkConnectionLiveData(val context: Context) : LiveData<Boolean>() {
private var connectivityManager: ConnectivityManager = context.getSystemService(CONNECTIVITY_SERVICE) as ConnectivityManager
private lateinit var connectivityManagerCallback: ConnectivityManager.NetworkCallback
override fun onActive() {
super.onActive()
updateConnection()
when {
Build.VERSION.SDK_INT >= Build.VERSION_CODES.N -> connectivityManager.registerDefaultNetworkCallback(getConnectivityManagerCallback())
Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP -> lollipopNetworkAvailableRequest()
else -> {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
context.registerReceiver(networkReceiver, IntentFilter("android.net.conn.CONNECTIVITY_CHANGE"))
}
}
}
}
override fun onInactive() {
super.onInactive()
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
connectivityManager.unregisterNetworkCallback(connectivityManagerCallback)
} else {
context.unregisterReceiver(networkReceiver)
}
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private fun lollipopNetworkAvailableRequest() {
val builder = NetworkRequest.Builder()
.addTransportType(android.net.NetworkCapabilities.TRANSPORT_CELLULAR)
.addTransportType(android.net.NetworkCapabilities.TRANSPORT_WIFI)
connectivityManager.registerNetworkCallback(builder.build(), getConnectivityManagerCallback())
}
private fun getConnectivityManagerCallback(): ConnectivityManager.NetworkCallback {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
connectivityManagerCallback = object : ConnectivityManager.NetworkCallback() {
override fun onAvailable(network: Network?) {
postValue(true)
}
override fun onLost(network: Network?) {
postValue(false)
}
}
return connectivityManagerCallback
} else {
throw IllegalAccessError("Should not happened")
}
}
private val networkReceiver = object : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
updateConnection()
}
}
private fun updateConnection() {
val activeNetwork: NetworkInfo? = connectivityManager.activeNetworkInfo
postValue(activeNetwork?.isConnected == true)
}
}
使用LiveData到任何类:
NetworkConnectionLiveData(context ?: return)
.observe(viewLifecycleOwner, Observer { isConnected ->
if (!isConnected) {
// Internet Not Available
return@Observer
}
// Internet Available
})
