java实现mqtt重连_Mqtt Paho(Java)的重连及使用
时间: 2023-08-06 15:01:45 浏览: 69
在使用Mqtt Paho(Java)时,如果连接中断或者网络不稳定,我们需要实现Mqtt客户端的重连机制,以保证消息的可靠传递。下面是一个实现Mqtt Paho(Java)重连的例子:
```java
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
public class MqttClientDemo {
private static final String BROKER_URL = "tcp://localhost:1883";
private static final String TOPIC = "test";
private static final String CLIENT_ID = "mqtt-java-client";
public static void main(String[] args) throws MqttException, InterruptedException {
MemoryPersistence persistence = new MemoryPersistence();
MqttClient client = new MqttClient(BROKER_URL, CLIENT_ID, persistence);
MqttConnectOptions options = new MqttConnectOptions();
options.setCleanSession(true);
options.setAutomaticReconnect(true); // 启用自动重连
client.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable throwable) {
System.out.println("Connection lost!");
}
@Override
public void messageArrived(String s, MqttMessage mqttMessage) throws Exception {
System.out.println("Message arrived: " + new String(mqttMessage.getPayload()));
}
@Override
public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
System.out.println("Delivery complete!");
}
});
client.connect(options);
client.subscribe(TOPIC, 1);
while (true) {
if (!client.isConnected()) {
System.out.println("Client disconnected! Trying to reconnect...");
client.connect(options);
client.subscribe(TOPIC, 1);
}
Thread.sleep(1000);
}
}
}
```
在这个例子中,我们设置了自动重连机制:
```java
options.setAutomaticReconnect(true);
```
然后在while循环中不断检查客户端是否连接,如果客户端断开了连接,就会尝试重新连接:
```java
if (!client.isConnected()) {
System.out.println("Client disconnected! Trying to reconnect...");
client.connect(options);
client.subscribe(TOPIC, 1);
}
```
这样就可以实现Mqtt Paho(Java)的重连了。
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