Android 使用广播检查互联网连接

Question

我想为我的互联网连接检查实现一个广播接收器。如果连接不存在就完成()；它。但我仍然搞砸了上下文。请检查我的以下代码。

/**
 * 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
     }

    }


}

安卓 list

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

登录目录:

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

Answer 1

您在 BroadcastReciever 中获得的上下文不是 Activity。 BroadcastReciever 在 Activity 之外工作并且不依赖于 Activity，除非您专门制作它。

抛开在不通知用户的情况下完成互联网 Activity 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();
        }

    }
}

将它用作其他 Activity 的父类(super class)(这个 Activity 从 Activity 扩展，将其更改为任何内容)，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父类(super class)