从android服务多次发送

我使用带有报警管理器的服务将数据发送到我的服务器。服务代码：

Intent intent = new Intent(this, onAlarmReceiver.class);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(this, sId, intent, PendingIntent.FLAG_CANCEL_CURRENT);
    alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
    int timeInterval = 14400;
    alarmManager.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime() + timeInterval * 1000,
            timeInterval * 1000, pendingIntent);

在onAlarmReceiver中，我正在尝试发送信息：

HTTPPoster.doPost(url, jsonToSendArray);

....


public static class HTTPPoster {
    public static HttpResponse doPost(String url, Object c) throws ClientProtocolException, IOException {
        HttpClient httpclient = new DefaultHttpClient();
        ((DefaultHttpClient) httpclient).setHttpRequestRetryHandler(new DefaultHttpRequestRetryHandler(0, false));
        HttpPost request = new HttpPost(url);
        HttpEntity entity;
        StringEntity s = new StringEntity(c.toString(), HTTP.UTF_8);            
        s.setContentType("application/json; charset=utf-8");
        s.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE, "application/json; charset=utf-8"));
        entity = s;
        request.setEntity(entity);
        HttpResponse response;
        response = httpclient.execute(request);
        return response;
    }
}

有时我在服务器上同时收到10个相同的请求。如何解决这个问题？ 谢谢

确保线程安全 使用最后一个请求的时间戳，并在请求正确之前检查是否延迟