我想实现一个广播接收器来检查互联网连接。如果连接不存在，只需完成（）；它。但我还是搞乱了上下文。请检查我下面的代码。
/**
* This broadcast receiver is awoken after boot and registers the service that
* checks for new photos from all the known contacts.
*/
public class ConnectionDetector extends BroadcastReceiver
{
@Override
public void onReceive(Context context, Intent intent) {
boolean noConnectivity = intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY,false);
if(noConnectivity){
((Activity)context).finish();
//Show Warning Message
//Close Application the way i suggested
}
}
}
Android清单
<receiver android:name=".ConnectionDetector"
android:label="NetworkConnection">
<intent-filter>
<action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
</intent-filter>
</receiver>
LogCat :
11-01 22:40:29.179: E/AndroidRuntime(29531): FATAL EXCEPTION: main
11-01 22:40:29.179: E/AndroidRuntime(29531): java.lang.RuntimeException: Unable to start receiver in.wptrafficanalyzer.actionbarsherlocknavtab.ConnectionDetector: java.lang.ClassCastException: android.app.ReceiverRestrictedContext
11-01 22:40:29.179: E/AndroidRuntime(29531): at android.app.ActivityThread.handleReceiver(ActivityThread.java:1809)
11-01 22:40:29.179: E/AndroidRuntime(29531): at android.app.ActivityThread.access$2400(ActivityThread.java:117)
11-01 22:40:29.179: E/AndroidRuntime(29531): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:985)
11-01 22:40:29.179: E/AndroidRuntime(29531): at android.os.Handler.dispatchMessage(Handler.java:99)
11-01 22:40:29.179: E/AndroidRuntime(29531): at android.os.Looper.loop(Looper.java:130)
11-01 22:40:29.179: E/AndroidRuntime(29531): at android.app.ActivityThread.main(ActivityThread.java:3691)
11-01 22:40:29.179: E/AndroidRuntime(29531): at java.lang.reflect.Method.invokeNative(Native Method)
11-01 22:40:29.179: E/AndroidRuntime(29531): at java.lang.reflect.Method.invoke(Method.java:507)
11-01 22:40:29.179: E/AndroidRuntime(29531): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:907)
11-01 22:40:29.179: E/AndroidRuntime(29531): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:665)
11-01 22:40:29.179: E/AndroidRuntime(29531): at dalvik.system.NativeStart.main(Native Method)
11-01 22:40:29.179: E/AndroidRuntime(29531): Caused by: java.lang.ClassCastException: android.app.ReceiverRestrictedContext
11-01 22:40:29.179: E/AndroidRuntime(29531): at in.wptrafficanalyzer.actionbarsherlocknavtab.ConnectionDetector.onReceive(ConnectionDetector.java:29)
11-01 22:40:29.179: E/AndroidRuntime(29531): at android.app.ActivityThread.handleReceiver(ActivityThread.java:1798)
11-01 22:40:29.179: E/AndroidRuntime(29531): ... 10 more
您在广播接收器中获得的上下文不是活动。 BroadcastReceiver 在活动之外工作，并且不依赖于活动，除非您专门制作它。
抛开在不通知用户的情况下仅完成互联网问题上的活动的不良做法，您可以执行以下操作：
public abstract class ConnectionAwareActivity extends Activity {
protected final IntentFilter mIntentFilter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION); // A filter for a BR. We want to listen to internet changes
protected final ConnectionDetector mConnectionDetector = new ConnectionDetector(); // Creating an instance of our BR for activity to use
@Override
protected void onResume() {
super.onResume();
try {
registerReceiver(mConnectionDetector, mIntentFilter); // Activity gets shown, we register a BR and it starts to receive notifications about internet changes
} catch (Exception exc) {
// whoops
}
}
@Override
protected void onPause() {
super.onPause();
try {
unregisterReceiver(mConnectionDetector); // Try to unregister BR, since when activity is not visible to user, we don't want to perform any operations on internet change
} catch (Exception exc) {
// whoops
}
}
// Your BR that is encapsulated in Activity and therefore has access to it's methods, since it has access to Activity instance
protected class ConnectionDetector extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
boolean noConnectivity = intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, false);
if (noConnectivity) {
finish();
}
}
}
}
将其用作其他活动的超类（此活动从 Activity 扩展，将其更改为其他活动），必须在连接错误时终止。
这是非常基本的变体，并且有些错误，因为您更喜欢组合而不是超类
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