如果一个消息发送失败，比如因为 deviceToken 不合法，APNs 会在大约 500ms 后断掉链接，在断链前发送的消息也会发送失败；”的解决，JAVA写代码，真优雅！
https://github.com/notnoop/java-apns
private void monitorSocket(final Socket socket) {
logger.debug("Launching Monitoring Thread for socket {}", socket);
Thread t = threadFactory.newThread(new Runnable() {
final static int EXPECTED_SIZE = 6;
@SuppressWarnings("InfiniteLoopStatement")
@Override
public void run() {
logger.debug("Started monitoring thread");
try {
InputStream in;
try {
in = socket.getInputStream();
} catch (IOException ioe) {
in = null;
}
byte[] bytes = new byte[EXPECTED_SIZE];
while (in != null && readPacket(in, bytes)) {
logger.debug("Error-response packet {}", Utilities.encodeHex(bytes));
// Quickly close socket, so we won't ever try to send push notifications
// using the defective socket.
Utilities.close(socket);
int command = bytes[0] & 0xFF;
if (command != 8) {
throw new IOException("Unexpected command byte " + command);
}
int statusCode = bytes[1] & 0xFF;
DeliveryError e = DeliveryError.ofCode(statusCode);
int id = Utilities.parseBytes(bytes[2], bytes[3], bytes[4], bytes[5]);
logger.debug("Closed connection cause={}; id={}", e, id);
delegate.connectionClosed(e, id);
Queue<ApnsNotification> tempCache = new LinkedList<ApnsNotification>();
ApnsNotification notification = null;
boolean foundNotification = false;
while (!cachedNotifications.isEmpty()) {
notification = cachedNotifications.poll();
logger.debug("Candidate for removal, message id {}", notification.getIdentifier());
if (notification.getIdentifier() == id) {
logger.debug("Bad message found {}", notification.getIdentifier());
foundNotification = true;
break;
}
tempCache.add(notification);
}
if (foundNotification) {
logger.debug("delegate.messageSendFailed, message id {}", notification.getIdentifier());
delegate.messageSendFailed(notification, new ApnsDeliveryErrorException(e));
} else {
cachedNotifications.addAll(tempCache);
int resendSize = tempCache.size();
logger.warn("Received error for message that wasn't in the cache...");
if (autoAdjustCacheLength) {
cacheLength = cacheLength + (resendSize / 2);
delegate.cacheLengthExceeded(cacheLength);
}
logger.debug("delegate.messageSendFailed, unknown id");
delegate.messageSendFailed(null, new ApnsDeliveryErrorException(e));
}
int resendSize = 0;
while (!cachedNotifications.isEmpty()) {
resendSize++;
final ApnsNotification resendNotification = cachedNotifications.poll();
logger.debug("Queuing for resend {}", resendNotification.getIdentifier());
notificationsBuffer.add(resendNotification);
}
logger.debug("resending {} notifications", resendSize);
delegate.notificationsResent(resendSize);
drainBuffer();
}
logger.debug("Monitoring input stream closed by EOF");
} catch (IOException e) {
// An exception when reading the error code is non-critical, it will cause another retry
// sending the message. Other than providing a more stable network connection to the APNS
// server we can't do much about it - so let's not spam the application's error log.
logger.info("Exception while waiting for error code", e);
delegate.connectionClosed(DeliveryError.UNKNOWN, -1);
} finally {
close();
}
}