以下是一个完整的Java代码示例，展示了如何使用Eclipse Paho MQTT客户端库在Java中实现TLS/SSL加密的MQTT通信。在这个示例中，我们将创建一个简单的MQTT客户端，该客户端连接到支持TLS/SSL的MQTT代理，并发布和订阅消息。

首先，确保你的项目中包含了Eclipse Paho MQTT客户端库的依赖。如果你使用Maven，可以在pom.xml文件中添加如下依赖：

xml复制代码

	<dependencies>
	<dependency>
	<groupId>org.eclipse.paho</groupId>
	<artifactId>org.eclipse.paho.client.mqttv3</artifactId>
	<version>1.2.5</version> <!-- 请检查并使用最新版本 -->
	</dependency>
	</dependencies>

接下来是Java代码示例：

java复制代码

	import org.eclipse.paho.client.mqttv3.*;
	import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
	import javax.net.ssl.*;
	import java.security.KeyStore;
	import java.security.KeyStoreException;
	import java.security.NoSuchAlgorithmException;
	import java.security.cert.CertificateException;
	import java.util.Properties;
	public class SecureMqttClient {
	public static void main(String[] args) {
	String brokerUrl = "ssl://mqtt.yourbroker.com:8883"; // 替换为你的MQTT代理地址和端口
	String clientId = "JavaSecureMqttClient";
	String topic = "test/topic";
	String content = "Hello, MQTT with TLS/SSL!";
	int qos = 2;
	try {
	// 配置MQTT客户端
	MqttClient client = new MqttClient(brokerUrl, clientId, new MemoryPersistence());
	MqttConnectOptions connOpts = new MqttConnectOptions();
	connOpts.setCleanSession(true);
	// 加载并配置SSL上下文
	SSLContext sslContext = SSLContext.getInstance("TLS");
	KeyStore keyStore = KeyStore.getInstance("JKS");
	// 加载信任库，替换为你的信任库路径和密码
	keyStore.load(SecureMqttClient.class.getResourceAsStream("/path/to/your/truststore.jks"), "yourTrustStorePassword".toCharArray());
	TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
	trustManagerFactory.init(keyStore);
	// 初始化SSL上下文
	sslContext.init(null, trustManagerFactory.getTrustManagers(), null);
	// 设置SSL套接字工厂
	SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();
	connOpts.setSocketFactory(sslSocketFactory);
	// 设置其他连接选项
	connOpts.setAutomaticReconnect(true);
	connOpts.setConnectionTimeout(10);
	connOpts.setKeepAliveInterval(60);
	// 注册回调以处理连接丢失、消息到达和消息完成事件
	client.setCallback(new MqttCallback() {
	@Override
	public void connectionLost(Throwable cause) {
	System.out.println("Connection lost: " + cause.getMessage());
	}
	@Override
	public void messageArrived(String topic, MqttMessage message) throws Exception {
	System.out.println("Message arrived on topic: " + topic);
	System.out.println("Message content: " + new String(message.getPayload()));
	}
	@Override
	public void deliveryComplete(IMqttDeliveryToken token) {
	System.out.println("Delivery complete for token: " + token.getToken());
	}
	});
	// 连接到MQTT代理
	client.connect(connOpts);
	// 发布消息
	MqttMessage mqttMessage = new MqttMessage(content.getBytes());
	mqttMessage.setQos(qos);
	client.publish(topic, mqttMessage);
	// 订阅主题
	client.subscribe(topic, qos);
	// 等待一段时间以接收消息
	Thread.sleep(5000);
	// 断开连接并关闭客户端
	client.disconnect();
	client.close();
	} catch (MqttException me) {
	System.out.println("MQTT Exception: " + me.getMessage());
	me.printStackTrace();
	} catch (NoSuchAlgorithmException | KeyStoreException | CertificateException | KeyManagementException | InterruptedException e) {
	System.out.println("Exception: " + e.getMessage());
	e.printStackTrace();
	}
	}
	}

在这个示例