使用java编写gatling mqtt插件

以下是使用 Java 编写 Gatling MQTT 插件的大致步骤：

1. 引入 Gatling 和 Eclipse Paho MQTT 客户端库：在 Maven 或 Gradle 项目中，需要在项目的 pom.xml 或 build.gradle 文件中引入 Gatling 和 Eclipse Paho MQTT 客户端库。

2. 创建 MQTT 插件类：创建一个 MQTT 插件类，实现 Gatling 的 io.gatling.core.protocol.Protocol 和 io.gatling.core.action.Action 接口。

3. 实现 MQTT Protocol：在 MQTT 插件类中实现 MQTT Protocol，用于配置 MQTT 客户端的连接参数。

public class MqttProtocol implements Protocol {
    private final String brokerUrl;
    private final String clientId;
    private final MqttConnectOptions mqttConnectOptions;
 
    public MqttProtocol(String brokerUrl, String clientId, MqttConnectOptions mqttConnectOptions) {
        this.brokerUrl = brokerUrl;
        this.clientId = clientId;
        this.mqttConnectOptions = mqttConnectOptions;
    }
 
    public String getBrokerUrl() {
        return brokerUrl;
    }
 
    public String getClientId() {
        return clientId;
    }
 
    public MqttConnectOptions getMqttConnectOptions() {
        return mqttConnectOptions;
    }
}

4. 实现 MQTT Action：在 MQTT 插件类中实现 MQTT Action，例如 SubscribeAction 和 PublishAction。

public class SubscribeAction extends Action {
    private final String topic;
    private final int qos;
    private final String variableName;
    private final MqttClient mqttClient;
 
    public SubscribeAction(String topic, int qos, String variableName, MqttClient mqttClient, Action next) {
        super(next);
        this.topic = topic;
        this.qos = qos;
        this.variableName = variableName;
        this.mqttClient = mqttClient;
    }
 
    @Override
    public void execute(Session session) {
        mqttClient.setCallback(new MqttCallback() {
            @Override
            public void connectionLost(Throwable throwable) {
                // TODO: Implement connection lost handling
            }
 
            @Override
            public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
                session.set(variableName, mqttMessage.toString());
            }
 
            @Override
            public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
                // TODO: Implement delivery complete handling
            }
        });
 
        mqttClient.subscribe(topic, qos);
 
        // Execute the next action in the chain
        next.execute(session);
    }
}
 
public class PublishAction extends Action {
    private final String topic;
    private final int qos;
    private final String payload;
    private final MqttClient mqttClient;
 
    public PublishAction(String topic, int qos, String payload, MqttClient mqttClient, Action next) {
        super(next);
        this.topic = topic;
        this.qos = qos;
        this.payload = payload;
        this.mqttClient = mqttClient;
    }
 
    @Override
    public void execute(Session session) {
        MqttMessage message = new MqttMessage(payload.getBytes());
        message.setQos(qos);
 
        try {
            mqttClient.publish(topic, message);
        } catch (MqttException e) {
            // TODO: Implement publish exception handling
        }
 
        // Execute the next action in the chain
        next.execute(session);
    }
}

5. 实现 MQTT 插件类：在 MQTT 插件类中实现 io.gatling.core.protocol.Protocol 和 io.gatling.core.action.Action 接口。

public class MqttPlugin implements Protocol, Action {
    private final MqttProtocol mqttProtocol;
    private final String topic;
    private final int qos;
    private final String payload;
 
    public MqttPlugin(MqttProtocol mqttProtocol, String topic, int qos, String payload) {
        this.mqttProtocol = mqttProtocol;
        this.topic = topic;
        this.qos = qos;
        this.payload = payload;
    }
 
    @Override
    public Action apply(Session session) {
        MqttClient mqttClient = null;
 
        try {
            mqttClient = new MqttClient(mqttProtocol.getBrokerUrl(), mqttProtocol.getClientId());
            mqttClient.connect(mqttProtocol.getMqttConnectOptions());
        } catch (MqttException e) {
            // TODO: Implement connection exception handling
        }
 
        Action subscribeAction = new SubscribeAction(topic, qos, "mqttMessage", mqttClient, null);
        Action publishAction = new PublishAction(topic, qos, payload, mqttClient, subscribeAction);
 
        return publishAction;
    }
 
    @Override
    public String name() {
        return "mqtt";
    }
}

6. 编写场景脚本：在 Gatling 场景脚本中，使用 MQTT Protocol 连接 MQTT 服务器，并使用 MQTT Action 进行订阅和发布消息。

import io.gatling.core.Predef._
import io.gatling.http.Predef._
import org.eclipse.paho.client.mqttv3.MqttConnectOptions
 
class MqttSimulation extends Simulation {
 
  val mqttProtocol = new MqttProtocol("tcp://localhost:1883", "clientId", new MqttConnectOptions)
  val mqttPlugin = new MqttPlugin(mqttProtocol, "test", 0, "Hello world")
 
  val scn = scenario("MQTT Test")
    .exec(mqttPlugin)
 
  setUp(scn.inject(atOnceUsers(1)))
}

7. 运行测试：使用 Gatling 运行 MQTT 场景脚本。

以上是使用 Java 编写 Gatling MQTT 插件的大致步骤，具体实现可能会根据项目的需求进行调整和修改。