以下是Java代码实现从MQTT读取数据并保存到
iotdb时序数据库的示例：
1. 引入相关库文件
```
<dependency>
<groupId>org.eclipse.paho</groupId>
<artifactId>org.eclipse.paho.client.mqttv3</artifactId>
<version>1.2.5</version>
</dependency>
<dependency>
<groupId>org.apache.
iotdb</groupId>
<artifactId>
iotdb-
jdbc</artifactId>
<version>0.10.0</version>
</dependency>
```
2.
连接MQTT服务器
```
String brokerUrl = "tcp://localhost:1883"; //MQTT服务器地址
String clientId = "
iotdb"; //客户端ID
MemoryPersistence persistence = new MemoryPersistence
();
MqttClient mqttClient = new MqttClient
(brokerUrl, clientId, persistence
);
mqttClient.connect
();
```
3. 订阅MQTT主题
```
String topic = "my/topic"; //订阅的主题
int qos = 1; //消息质量
mqttClient.subscribe
(topic, qos
);
```
4. 接收MQTT消息并保存到
iotdb时序数据库
```
String
iotdbUrl = "
jdbc:
iotdb://localhost:6667/"; //
iotdb数据库地址
String
iotdbUsername = "root"; //
iotdb数据库用户名
String
iotdbPassword = "root"; //
iotdb数据库密码
String
iotdbStorageGroup = "root.my"; //
iotdb存储组
String
iotdbMeasurement = "sensor1"; //
iotdb测点名称
String
iotdbDataType = "DOUBLE"; //
iotdb数据类型
String
iotdbEncoding = "PLAIN"; //
iotdb编码方式
String
iotdbTimeseries =
iotdbStorageGroup + "." +
iotdbMeasurement; //
iotdb时序列名
Class.forName
("org.apache.
iotdb.
jdbc.
IoTDBDriver"
);
Connection connection = DriverManager.getConnection
(iotdbUrl,
iotdbUsername,
iotdbPassword
);
Statement statement = connection.createStatement
();
mqttClient.setCallback
(new MqttCallback
() {
@Override
public void connectionLost
(Throwable throwable
) {
System.out.println
("MQTT
连接断开"
);
}
@Override
public void messageArrived
(String topic, MqttMessage mqttMessage
) {
String message = new String
(mqttMessage.getPayload
());
System.out.println
("收到MQTT消息：" + message
);
try {
String sql = String.format
("insert into %s
(time,%s
) values
(%d,%s
)",
iotdbTimeseries,
iotdbDataType,
iotdbEncoding,
System.currentTimeMillis
(), message
);
statement.execute
(sql
);
System.out.println
("保存到
iotdb成功"
);
} catch
(SQLException e
) {
System.out.println
("保存到
iotdb失败：" + e.getMessage
());
}
}
@Override
public void deliveryComplete
(IMqttDeliveryToken iMqttDeliveryToken
) {
}
}
);
```
5. 断开MQTT
连接
```
mqttClient.disconnect
();
```
完整代码示例：
```
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class MqttTo
Iotdb {
public static void main
(String[] args
) throws MqttException, ClassNotFoundException, SQLException {
String brokerUrl = "tcp://localhost:1883"; //MQTT服务器地址
String clientId = "
iotdb"; //客户端ID
MemoryPersistence persistence = new MemoryPersistence
();
MqttClient mqttClient = new MqttClient
(brokerUrl, clientId, persistence
);
mqttClient.connect
();
String topic = "my/topic"; //订阅的主题
int qos = 1; //消息质量
mqttClient.subscribe
(topic, qos
);
String
iotdbUrl = "
jdbc:
iotdb://localhost:6667/"; //
iotdb数据库地址
String
iotdbUsername = "root"; //
iotdb数据库用户名
String
iotdbPassword = "root"; //
iotdb数据库密码
String
iotdbStorageGroup = "root.my"; //
iotdb存储组
String
iotdbMeasurement = "sensor1"; //
iotdb测点名称
String
iotdbDataType = "DOUBLE"; //
iotdb数据类型
String
iotdbEncoding = "PLAIN"; //
iotdb编码方式
String
iotdbTimeseries =
iotdbStorageGroup + "." +
iotdbMeasurement; //
iotdb时序列名
Class.forName
("org.apache.
iotdb.
jdbc.
IoTDBDriver"
);
Connection connection = DriverManager.getConnection
(iotdbUrl,
iotdbUsername,
iotdbPassword
);
Statement statement = connection.createStatement
();
mqttClient.setCallback
(new MqttCallback
() {
@Override
public void connectionLost
(Throwable throwable
) {
System.out.println
("MQTT
连接断开"
);
}
@Override
public void messageArrived
(String topic, MqttMessage mqttMessage
) {
String message = new String
(mqttMessage.getPayload
());
System.out.println
("收到MQTT消息：" + message
);
try {
String sql = String.format
("insert into %s
(time,%s
) values
(%d,%s
)",
iotdbTimeseries,
iotdbDataType,
iotdbEncoding,
System.currentTimeMillis
(), message
);
statement.execute
(sql
);
System.out.println
("保存到
iotdb成功"
);
} catch
(SQLException e
) {
System.out.println
("保存到
iotdb失败：" + e.getMessage
());
}
}
@Override
public void deliveryComplete
(IMqttDeliveryToken iMqttDeliveryToken
) {
}
}
);
//等待MQTT消息
while
(true
) {
}
//断开MQTT
连接
//mqttClient.disconnect
();
}
}
```
IoTDB时序数据库连接教程
本文详细介绍了如何在项目中使用IoTDB时序数据库，包括在pom文件中添加依赖，创建数据库连接，初始化数据库，以及测试和关闭连接的过程。提供了从配置到测试的完整步骤。
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