Spring Boot RabbitMQ Receiver Jackson 反序列化为 POJO

Question

我有一个 spring boot 项目，我正在尝试与 rabbitmq 服务器集成，以便可以向队列发布和读取消息。

这是我的 rabbitmq 配置（编辑为仅显示相关详细信息）：

@Configuration
@ConfigurationProperties(prefix="rabbit")
public class RabbitConfig {
    private String queue;

    @Bean
    Queue queue() {
        return new Queue(queue, durable);
    }

    @Bean
    public MessageConverter jsonMessageConverter(){
        return new Jackson2JsonMessageConverter();
    }

    @Bean
    SimpleMessageListenerContainer container(ConnectionFactory connectionFactory, Queue queue,
                                             MessageListenerAdapter listenerAdapter, MessageConverter messageConverter) {
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer(connectionFactory);
        container.setQueues(queue);
        container.setMessageListener(listenerAdapter);
        container.setMessageConverter(messageConverter);
        return container;
    }

    @Bean
    MessageListenerAdapter listenerAdapter(Receiver receiver) {
        return new MessageListenerAdapter(receiver);
    }

    public void setQueue(String queue) {
        this.queue = queue;
    }
}

这是我的接收器类：

public interface Receiver {
    void handleMessage(FooA message);
}

@Component
public class RabbitReceiver implements Receiver {
    @Override
    public void handleMessage(FooA message) {
        System.out.println(message);
    }
}

还有我的pojo：

public class FooA {}
    private double num;
    private Map<String, String> map = new HashMap();

    public FooA() {
    }

    public FooA(double num, Map<String, String> map) {
        this.num = num;
        this.map = map;
    }

    public int getnum() {
        return num;
    }

    public Map<String, String> getMap() {
        return map;
    }
}

我成功地将FooA 消息对象发布到队列。这是队列中的样子：

[
    {
        "payload_bytes": 41,
        "redelivered": false,
        "exchange": "amq.fanout",
        "routing_key": "",
        "message_count": 0,
        "properties": {
            "priority": 0,
            "delivery_mode": 2,
            "headers": {
                "__TypeId__": "com.test.FooA"
            },
            "content_encoding": "UTF-8",
            "content_type": "application/json"
        },
        "payload": "{\"num\":1.2,\"map\":{}}",
        "payload_encoding": "string"
    }
]

但是当我尝试从队列中读取时，我得到了这个错误：

org.springframework.amqp.rabbit.listener.exception.ListenerExecutionFailedException: Failed to invoke target method 'handleMessage' with argument type = [class [B], value = [{[B@75a7bfc9}]
    at org.springframework.amqp.rabbit.listener.adapter.MessageListenerAdapter.invokeListenerMethod(MessageListenerAdapter.java:408) ~[spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.adapter.MessageListenerAdapter.onMessage(MessageListenerAdapter.java:298) ~[spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:822) ~[spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:745) ~[spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$001(SimpleMessageListenerContainer.java:97) [spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$1.invokeListener(SimpleMessageListenerContainer.java:189) ~[spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.invokeListener(SimpleMessageListenerContainer.java:1276) [spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:726) ~[spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:1219) [spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:1189) [spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1500(SimpleMessageListenerContainer.java:97) [spring-rabbit-1.7.3.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1421) [spring-rabbit-1.7.3.RELEASE.jar:na]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_121]
Caused by: java.lang.NoSuchMethodException: com.test.RabbitReceiver.handleMessage([B)
    at java.lang.Class.getMethod(Class.java:1786) ~[na:1.8.0_121]
    at org.springframework.util.MethodInvoker.prepare(MethodInvoker.java:174) ~[spring-core-4.3.9.RELEASE.jar:4.3.9.RELEASE]
    at org.springframework.amqp.rabbit.listener.adapter.MessageListenerAdapter.invokeListenerMethod(MessageListenerAdapter.java:386) ~[spring-rabbit-1.7.3.RELEASE.jar:na]
    ... 12 common frames omitted

我做错了什么？

编辑1：我把方法改成：

@Override
public void handleMessage(byte[] message) {
    System.out.println(message);
}

哪个有效，但完全无法使用。它只是这样显示：

如何将其映射到我的 pojo FooA

Answer 1

我刚刚让实现Serializable 接口的类删除了JsonMessageConverter。 Json 和 Serializable 是冲突的，所以它不起作用。

Answer 2

将 bytearray 转换为字符串并使用 jackson mapper (ObjectMapper) 映射到您的 pojo。您的映射器上有配置：例如

 this.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    this.configure(SerializationFeature.WRITE_NULL_MAP_VALUES, false);
    this.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
    this.registerModule(new JavaTimeModule())

Answer 3

看起来消息是作为字符串而不是 JSON 发布的。 就是这样看的

"payload_encoding": "string"

Spring 可以自动将此字符串转换为 byte[]，如屏幕截图所示。

您还需要像这样在 RabbitTemplate 上设置消息转换器：

@Bean
public RabbitTemplate rabbitTemplate(ConnectionFactory connectionFactory,MessageConverter rabbitJsonMessageConverter) {
    RabbitTemplate template = new RabbitTemplate(connectionFactory);
    template.setMessageConverter(rabbitJsonMessageConverter);
    return template;
}

这应该正确地将消息发布为 JSON。

Answer 4

你做的一切都是正确的。但是您没有向MessageListenerAdapter 提供任何方法来接收和处理您的消息。这就是您收到 ListenerExecutionFailedException: Failed to invoke target method 'handleMessage' 的原因。

要修复此更改，请使用以下代码：

@Bean
    MessageListenerAdapter listenerAdapter(Receiver receiver) {
        return new MessageListenerAdapter(receiver);
    }

到：

@Bean
    MessageListenerAdapter listenerAdapter(Receiver receiver) {
        return new MessageListenerAdapter(receiver, "handleMessage");
    }

Answer 5

本文展示了如何以更简单的方式解决此问题：https://thepracticaldeveloper.com/produce-and-consume-json-messages-with-spring-boot-amqp/

配置：

@Bean
public RabbitTemplate rabbitTemplate(final ConnectionFactory connectionFactory) {
    final var rabbitTemplate = new RabbitTemplate(connectionFactory);
    rabbitTemplate.setMessageConverter(producerJackson2MessageConverter());
    return rabbitTemplate;
}

@Bean
public Jackson2JsonMessageConverter producerJackson2MessageConverter() {
    return new Jackson2JsonMessageConverter();
}

听众：

@RabbitListener(queues = MessagingApplication.QUEUE_SPECIFIC_NAME)
public void receiveMessage(final CustomMessage customMessage) {
    log.info("Received message and deserialized to 'CustomMessage': {}", customMessage.toString());
}

POJO：

public record CustomMessage(@JsonProperty("text") String text,
                            @JsonProperty("priority") int priority,
                            @JsonProperty("secret") boolean secret)
        implements Serializable {
}