mqtt支持多少个topic_w5500 mqtt

import java.io.UnsupportedEncodingException;
import java.util.List;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.MqttSecurityException;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;

public class MyMqttClient {
       String clientId;
	private MemoryPersistence persistence = new MemoryPersistence();

	// Private instance variables
	private MqttClient client;
	private String brokerUrl;
	private MqttConnectOptions conOpt;
	private boolean clean;
	private String password;
	private String userName;

	//需要重新订阅的主题
	private List<String> topicList;

	
	
	public MyMqttClient() {
		super();
	}



	public MyMqttClient(String brokerUrl, String clientId, boolean cleanSession, String userName, String password)
			throws MqttException {
		super();
		this.brokerUrl = brokerUrl;
		this.clientId = clientId;
		this.clean = cleanSession;
		this.password = password;
		this.userName = userName;
		// 建立mqtt连接属性
		this.conOpt = new MqttConnectOptions();
		this.conOpt.setConnectionTimeout(60);
//		this.conOpt.setKeepAliveInterval(60);
		this.conOpt.setCleanSession(true);
		// 初始化客户端
		this.client = new MqttClient(brokerUrl, clientId, new MemoryPersistence());
		this.client.setCallback(new MyMqttCallback(this));
	}

	
	
	public List<String> getTopicList() {
		return topicList;
	}


	public void setTopicList(List<String> topicList) {
		this.topicList = topicList;
	}



	public void connect() {
		try {
			if (!this.client.isConnected()) {
				this.client.connect(this.conOpt);
			}
		} catch (MqttException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public void subscribe(String topicName, int qos) {
		try {
			this.client.subscribe(topicName, qos);
		} catch (MqttException e) {
			e.printStackTrace();
		}
	}

	public void publish(String topicName, String message, int qos) {
		try {
			MqttMessage mqttMessage = new MqttMessage();
			mqttMessage.setQos(qos);
			mqttMessage.setPayload(message.getBytes("utf-8"));
			this.client.publish(topicName, mqttMessage);
		} catch (MqttException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public void close() {
		try {
			this.client.disconnect();
			this.client.close();
		} catch (MqttException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public void reConnect() throws MqttSecurityException, MqttException {
		if (null != this.client) {
			if(!this.client.isConnected()) {
				client.connect(this.conOpt);
			}else {
				this.client.disconnect();
				this.client.connect(this.conOpt);
			}
		}
	}

}

import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.example.util.Config;
import com.example.util.HikariCPUtil;

public class MyMqttCallback implements MqttCallback {
	
	private static final Logger logger = LoggerFactory.getLogger(MyMqttCallback.class);
	private static final ExecutorService pool = Executors.newFixedThreadPool(5);
	/**
	 * 私有化的mqtt客户端，用以重连
	 */
	private MyMqttClient myClient;

	public MyMqttCallback(MyMqttClient myClient) {
		super();
		this.myClient = myClient;
	}

	/**
	 * 设置重连机制
	 */
	@Override
	public void connectionLost(Throwable cause) {
		logger.error("连接丢失,原因{}",cause);
		// 连接丢失后，一般在这里面进行重连
		while (true) {
			try {
				Thread.sleep(30000);
				myClient.reConnect();
				List<String> topicList = this.myClient.getTopicList();
				for (String topic : topicList) {
					this.myClient.subscribe(topic, Config.QOS);
				}
				logger.info("mqtt重新连接，重新订阅！");
				break;
			} catch (Exception e) {
				e.printStackTrace();
				continue;
			}
		}
	}

	@Override
	public void messageArrived(String topic, MqttMessage message) throws Exception {

                //消息处理
	}

	@Override
	public void deliveryComplete(IMqttDeliveryToken token) {
		// TODO Auto-generated method stub
	}
	
}