Sms ContentObserver onChange() fires multiple time

问题:

I know this question has been asked multiple times, but nobody has been able to come up with a working answer from what I have seen.

Im working on an app to intercept text messages and depending on the sending #, pop up with a custom alert. I have it working beautifully with a broadcast receiver, however if the user has goSms installed the onReceive() method is never called as goSms aborts it before it ever reaches my app.

To get around this, Im trying a content observer on content://sms/ Its working just fine, however the onChange() is called twice, with exactly the same parameters. Ive tried to check the time stamps, but they are the same, as is the type and every other parameter I have set.

From what I've seen, this is a common issue, but not one that I've seen answered anywhere.

    @Override
public void onChange(boolean selfChange) {
    super.onChange(selfChange);
    querySMS();
}

protected void querySMS() {
    Cursor cur = getContentResolver().query(u, null, null, null, null);
    cur.moveToNext(); // this will make it point to the first record, which is the last SMS sent
    String type = cur.getString(cur.getColumnIndex("type"));
    String body = cur.getString(cur.getColumnIndex("body")); //content of sms
    String add = cur.getString(cur.getColumnIndex("address")); //phone num
    if (type.equals("1")) {
        if (add.equals(Test.SENDER)) {              
            String[] bodys = body.split(" ", 7);
            if (bodys[0].equals("test")) {
                test = true;
            }
            cat = bodys[1];
            level = bodys[2];
            urgency = bodys[3];
            certainty = bodys[4];
            carrier = bodys[5];
            message = bodys[6];
            final Intent intent = new Intent(context, AlertActivity.class);
            Bundle b = new Bundle();
            b.putString("title", cat);
            b.putString("certainty", certainty);
            b.putString("urgency", urgency);
            b.putString("level", level);
            b.putString("message", message);
            b.putBoolean("test", test);
            intent.putExtras(b);
            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            TelephonyManager manager = (TelephonyManager)context.getSystemService(Context.TELEPHONY_SERVICE);
            carrierName = manager.getNetworkOperatorName();
            if (carrierName.replaceAll(" ", "").equals(carrier)) {

                context.startActivity(intent);
            } else {
                //testing
                Toast.makeText(context, carrierName.replaceAll(" ", ""), Toast.LENGTH_LONG).show();
            }
        }
    }
}

Because of the onChange() being fired twice, Im getting two alerts as well. I cannot for the life of me figure out a way around this.

回答1:

If the two are identical:
store each message recv'd
compare it to previous messages recv'd
if not found, process
if found, discard the message

The life of the messages stored should be infinitesimal, a little circular buffer of 5 messages should be fine.

回答2:

here is my code, it works fine for me

public class SmsObserver extends ContentObserver {  
    private Context context;
    private static int initialPos;
    private static final String TAG = "SMSContentObserver";
    private static final Uri uriSMS = Uri.parse("content://sms/sent");

    public SmsObserver(Handler handler, Context ctx) {
        super(handler);
        context = ctx;
        initialPos = getLastMsgId();

    }

    @Override
    public void onChange(boolean selfChange) {
        super.onChange(selfChange);
        queryLastSentSMS();
    }

    public int getLastMsgId() {

        Cursor cur = context.getContentResolver().query(uriSMS, null, null, null, null);
        cur.moveToFirst();
        int lastMsgId = cur.getInt(cur.getColumnIndex("_id"));
        Log.i(TAG, "Last sent message id: " + String.valueOf(lastMsgId));
        return lastMsgId;
    }

    protected void queryLastSentSMS() {

        new Thread(new Runnable() {

            @Override
            public void run() {
                Cursor cur =
                    context.getContentResolver().query(uriSMS, null, null, null, null);

                if (cur.moveToNext()) {


                    try {
                        if (initialPos != getLastMsgId()) {
                            // Here you get the last sms. Do what you want.
                            String receiver = cur.getString(cur.getColumnIndex("address"));
                           System.out.println(" Receiver Ph no :"+receiver);


                            // Then, set initialPos to the current position.
                            initialPos = getLastMsgId(); 
                        }
                    } catch (Exception e) {
                        // Treat exception here
                    }
                }
                cur.close();
            }
        }).start();

    }

}//End of class SmsObserver

回答3:

You can save last message's id and compare it to the id of the message that is returned by cur in onChange. you then can simply disregard the message if ids are the same.

// might contain mistakes, but you'll get the idea:
protected void querySMS() {
    Cursor cur = getContentResolver().query(u, null, null, null, null);
    cur.moveToNext(); 
    if (lastId == cur.getLong(cur.getColumnIndex("_id")))
        return;
    lastId = cur.getLong(cur.getColumnIndex("_id"));
    ... //continue as it was
}

However - GO SMS only prevents other app's from recieving Broadcast if the user selected this option (Recieve Settings - Disable other message notification) - so if the user does not want other apps to disturb him - I think it's good idea not to do so.

回答4:

I just use SharedPreference to remark last SMS info (like: id\type ...). if it is the same, I will return.