在Java中,使用EMqtt库实现消息去重可以通过以下方法:
EMqttClient client = EMqttClient.create("tcp://broker.emqx.io:1883", "unique_client_id");
String uniqueMessageId = message.getTopic() + "_" + client.getClientId();
Set<String> processedMessageIds = new HashSet<>();
client.setCallback(new EMqttCallback() {
@Override
public void connectComplete(EMqttConnectStatus status, String brokerUrl) {
// 连接成功后的操作
}
@Override
public void messageArrived(String topic, EMqttMessage message) {
String uniqueMessageId = message.getTopic() + "_" + client.getClientId();
if (!processedMessageIds.contains(uniqueMessageId)) {
// 处理消息
System.out.println("Received message: " + new String(message.getPayload()));
processedMessageIds.add(uniqueMessageId);
} else {
// 消息已处理过,不重复处理
System.out.println("Duplicate message ignored: " + new String(message.getPayload()));
}
}
// 其他回调方法留空
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
}
});
client.connect();
通过这种方法,你可以确保在Java中使用EMqtt库实现消息去重。