春季Mqtt集成：出站主題問題

Question

嗨我試圖使用彈簧集成來接收MQTT消息，處理它們併發布到另一個主題。

這裏是integration.xml：

<int-mqtt:outbound-channel-adapter id="mqtt-publish" 
    client-id="spring-foo-1" 
    client-factory="clientFactory" 
    auto-startup="true" 
    url="tcp://localhost:1883" 
    default-qos="0" 
    default-retained="true" 
    default-topic="tweets/akki" /> 

    <int-mqtt:message-driven-channel-adapter id="oneTopicAdapter" 
    client-id="spring-foo-2" 
    client-factory="clientFactory" 
    auto-startup="true" 
    url="tcp://localhost:1883" 
    topics="mqtt/publish" 
    /> 

    <int:service-activator input-channel="oneTopicAdapter" method="logMessages" ref="mqttLogger" output-channel="mqtt-publish"></int:service-activator> 

    <bean id="mqttLogger" class="hello.mqttReceiver" /> 

而且mqttReceiver.java：

package hello; 
public class mqttReceiver { 
    public String logMessages(String a){ 
     String processed_data = a; //TODO Process Data 
     return processed_data; 
    } 
} 

以下是問題，我面對：

• 的processed_data被送到mqtt/publish and not mqtt/akki
• The processed_data沒有發佈的信息，但很多時候

Answer 1

這是正確的，因爲AbstractMqttMessageHandler需要看首先進入headers：

String topic = (String) message.getHeaders().get(MqttHeaders.TOPIC); 
    Object mqttMessage = this.converter.fromMessage(message, Object.class); 
    if (topic == null && this.defaultTopic == null) { 
     throw new MessageHandlingException(message, 
       "No '" + MqttHeaders.TOPIC + "' header and no default topic defined"); 
    } 

當DefaultPahoMessageConverter填充從MqttPahoMessageDrivenChannelAdapter上消息到達MqttHeaders.TOPIC頭。

你應該考慮將消息發送到<int-mqtt:outbound-channel-adapter>