[Java知识库]【填坑向】Dispatcher has no subscribers for channel的MessageDispatchingException

报错详情

Dispatcher has no subscribers for channel 'mqttOutboundChannel'.; nested exception is org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers, failedMessage=GenericMessage []  

报错代码

/** 
 * @author aqin1012 AQin. 
 * @date 2022/2/23 9:16 AM 
 * @Version 1.0 
 */ 
@Configuration 
@IntegrationComponentScan 
public class MqttSenderConfig { 
 @Autowired 
    private MqttProperties prop; 
 
    @Autowired 
    MqttEncryptHelper mqttEncryptHelper; 
 
    @Bean 
    public MqttPahoClientFactory mqttClientFactory() { 
        DefaultMqttPahoClientFactory factory = new DefaultMqttPahoClientFactory(); 
        MqttConnectOptions mqttConnectOptions = new MqttConnectOptions(); 
        mqttConnectOptions.setServerURIs(new String[]{prop.getHostUrl()}); 
        mqttConnectOptions.setUserName(prop.getUsername()); 
        mqttConnectOptions.setPassword(prop.getPassword().toCharArray()); 
        // 客户端断线时暂时不清除，直到超时注销 
        mqttConnectOptions.setCleanSession(false); 
        mqttConnectOptions.setKeepAliveInterval(prop.getKeepAliveInterval()); 
        mqttConnectOptions.setAutomaticReconnect(true); 
        factory.setConnectionOptions(mqttConnectOptions); 
        return factory; 
 } 
 
    @Bean 
    @ServiceActivator(inputChannel = "mqttOutboundChannel") 
    public MessageHandler mqttOutbound() { 
        MqttPahoMessageHandler messageHandler = new MqttPahoMessageHandler( 
             prop.getClientId() + "-pub-" + Instant.now().toEpochMilli(),                 
             mqttClientFactory()); 
        messageHandler.setAsync(true); 
        messageHandler.setDefaultQos(0); 
        messageHandler.setDefaultTopic(prop.getSenderDispatchTopic()); 
        return messageHandler; 
 } 
  
    @Bean 
    public MessageChannel mqttOutboundChannel() { 
        return new DirectChannel(); 
 } 
 
} 

报错分析

由报错信息可以看出来是由于频道没有订阅者，由于我的mqttOutboundChannel()和mqttOutbound()是绑定的，在参考了https://www.infoflowing.com这篇问答（非常感谢～）后，我把给频道手动添加订阅者：

mqttOutboundChannel()?做如下修改：

@Bean 
public MessageChannel mqttOutboundChannel() { 
    DirectChannel dc = new DirectChannel(); 
    dc.subscribe(mqttOutbound()); 
    return dc; 
} 

再次运行服务

搞定～撒花 ！！！

很多博文给出的解决方案是添加注解?@EnableIntegration，但是我这边并未起作用（有知道原因的大佬麻烦不吝指导～～谢谢呢🙏）