用java编写获取MQTT地址接口

以下是一个用Java编写的获取MQTT地址接口的示例代码：

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttSecurityException;
import org.eclipse.paho.client.mqttv3.internal.security.SSLContextFactory;

@Path("/mqtt")
public class MQTTAddressController {

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String getMQTTAddress() {
        String mqttAddress = "tcp://example.com:1883"; // MQTT server address
        String mqttUsername = "user"; // MQTT username
        String mqttPassword = "password"; // MQTT password

        try {
            MqttConnectOptions options = new MqttConnectOptions();
            options.setUserName(mqttUsername);
            options.setPassword(mqttPassword.toCharArray());

            SSLContextFactory sslContextFactory = SSLContextFactory.getInstance();
            options.setSocketFactory(sslContextFactory.getSocketFactory());

            // Connect to the MQTT server and get the server URI
            String serverURI = options.getServerURIs()[0];
            if (serverURI.startsWith("ssl")) {
                mqttAddress = "ssl://"; // replace "tcp://" with "ssl://"
            }

            mqttAddress += serverURI.substring(serverURI.indexOf("://") + 3);
        } catch (MqttSecurityException e) {
            // Handle exceptions
        } catch (MqttException e) {
            // Handle exceptions
        }

        return mqttAddress; // Return the MQTT server URI
    }
}

这个接口通过访问`/mqtt`路径，使用HTTP GET方法获取MQTT服务器地址。在这个例子中，我们使用Eclipse Paho MQTT库连接到MQTT服务器。我们可以通过设置MQTT的用户名和密码以及SSL SocketFactory来配置连接选项。最后，我们将连接到的服务器地址转换为`tcp://`或`ssl://` URI格式，并返回它作为接口的响应。