ArrayList 内容的 spring-rabbit JSON 反序列化

Question

我正在使用带有 JSON 消息序列化的 rabbitmq 的 Spring-boot。使用 Direct-Reply-to 功能的回复无法反序列化 java.util.List 容器中的类。

在Jackson2JsonMessageConverter.fromMessage() 中使用我的调试器，MessageProperties 表明__TypeID__ 正确设置为java.util.ArrayList。但是 __ContentTypeId__ 是 java.lang.Object 是不正确的，因为我期待 FooDto （我假设......）。 异常消息是： java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to FooDto

请注意，我使用的是 spring-rabbit 1.7.3 而不是 v2.0，因此不能将 ParameterizedTypeReference 用于 rabbitTemplate.convertSendAndReceiveAsType() 方法。

我尝试使用DefaultClassMapper 和DefaultJackson2JavaTypeMapper（TypePrecedence 在TYPE_ID 和INFERRED 下测试）但没有成功：

private DefaultJackson2JavaTypeMapper classMapper() {
    final DefaultJackson2JavaTypeMapper classMapper = new DefaultJackson2JavaTypeMapper();
    final Map<String, Class<?>> idClassMapping = new HashMap<>();
    idClassMapping.put(FooDto.class.getSimpleName(), FooDto.class);
    classMapper.setIdClassMapping(idClassMapping);
return classMapper;
}

现在的例外是： java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to FooDto

到目前为止，我的解决方法是使用原始类型的数组，即FooDto[]。

库版本： - 弹簧启动 1.5.6 - 兔MQ：3.7.4 - 春兔 1.7.3

Maven pom.xml：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.6.RELEASE</version>
    <relativePath />
</parent>

<dependencies>
    <dependency>
    <groupId>org.springframework.amqp</groupId>
    <artifactId>spring-rabbit</artifactId>
    </dependency>    
</dependencies>

有效的 Pom：

<dependency>
    <groupId>org.springframework.amqp</groupId>
    <artifactId>spring-amqp</artifactId>
    <version>1.7.3.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework.amqp</groupId>
    <artifactId>spring-rabbit</artifactId>
    <version>1.7.3.RELEASE</version>
</dependency>

RabbitMQ 配置：

@Configuration
@EnableRabbit
public class MessagingConfiguration implements ShutdownListener {

    // FIXME: List<FooDto> in the direct-reply response contains  ArrayList<Object> due to __ContentTypeID__ == SimpleObject/Object .  __TypeID__ is correctly ArrayList

    @Bean
    public List<Declarable> bindings() {
    final List<Declarable> declarations = new ArrayList<>();
        final FanoutExchange exchange = new FanoutExchange("fx", true, false);
        final Queue queue = QueueBuilder.durable("orders").build();
        declarations.add(exchange);
        declarations.add(queue);
        declarations.add(BindingBuilder.bind(queue).to(exchange));
        return declarations;
    }

    // @Bean
    // public DefaultClassMapper classMapper() {
    // DefaultClassMapper classMapper = new DefaultClassMapper();
    // Map<String, Class<?>> idClassMapping = new HashMap<>();
    // idClassMapping.put("FooDto", FooDto.class);
    // java.util.List<FooDto>
    // classMapper.setIdClassMapping(idClassMapping);
    // return classMapper;
    // }
    //
    // @Bean
    // public DefaultClassMapper classMapper() {
    // final DefaultClassMapper typeMapper = new DefaultClassMapper();
    // // typeMapper.setDefaultType(new ArrayList<FooDto>().getClass());
    // typeMapper.setDefaultType(FooDto[].class);
    // return typeMapper;
    // }

    @Bean
    public Jackson2JsonMessageConverter jsonConverter() {
        // https://stackoverflow.com/questions/40491628/jackson-configuration-to-consume-list-of-records-in-rabbitmq
        // https://github.com/FasterXML/jackson-core/issues/295
        final Jackson2JsonMessageConverter converter = new Jackson2JsonMessageConverter();
        converter.setTypePrecedence(TypePrecedence.TYPE_ID);
        // converter.setClassMapper(classMapper());
        return converter;
    }

    @ConditionalOnProperty(name = "consumer", havingValue = "true")
    @Bean
    public ConsumerListener listenerConsumer() {
        return new ConsumerListener();
    }

    @ConditionalOnProperty(name = "producer", havingValue = "true")
    @Bean
    public ProducerListener listenerProducer() {
        return new ProducerListener();
    }

    @Bean
    public RabbitAdmin rabbitAdmin(final CachingConnectionFactory connectionFactory) {
        return new RabbitAdmin(connectionFactory);
    }

    @Bean
    public SimpleRabbitListenerContainerFactory rabbitListenerContainerFactory(
            final ConnectionFactory connectionFactory) {
        // Setting the annotation @RabbitListener to use Jackson2JsonMessageConverter
        final SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
        factory.setConnectionFactory(connectionFactory);
        factory.setMessageConverter(jsonConverter());
        factory.setConcurrentConsumers(5);
        factory.setMaxConcurrentConsumers(5);
        return factory;
    }

    @Bean
    public RabbitTemplate rabbitTemplate(final ConnectionFactory connectionFactory) {
        final RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
        rabbitTemplate.setMessageConverter(jsonConverter()); // convert all sent messages to JSON
        rabbitTemplate.setReplyTimeout(TimeUnit.SECONDS.toMillis(3));
        rabbitTemplate.setReceiveTimeout(TimeUnit.SECONDS.toMillis(3));
        return rabbitTemplate;
    }

    @Override
    public void shutdownCompleted(final ShutdownSignalException arg0) {
    }
}

侦听器在交换“fx”上使用包含来自队列“订单”的 MyQuery 对象的消息：

public class ConsumerListener {
    private static final Logger log = LoggerFactory.getLogger(ConsumerListener.class);

    @RabbitListener(queues = { "orders" })
    public FooDto[] receiveMessage(final MyQuery query) {
        log.info(query);
        List<FooDto> response = new ArrayList<>();
        response.add(new FooDto());
        response.add(new FooDto());
        response.add(new FooDto());
        return response;
    }
}

向 Exchange 发送消息时使用的 POJO： 类 MyQuery { 私有字符串内容=“测试”；

    public MyQuery();

    public String toString() {
        return content;
    }
}

用于响应的 POJO： 类FooDto { 私有字符串内容 = "foo";

    public FooDto();

    public String toString() {
        return content;
    }
}

Answer 1

你的听众有些奇怪；它的返回类型为void，但您返回一个列表。

也就是说，我认为问题是由于类型擦除造成的。

自定义 ClassMapper 不会有帮助，因为那只是用于顶级课程。

但是，您应该能够构造自定义 Jackson2JavaTypeMapper 以创建更复杂的类型。如果没有类映射器，则查询类型映射器。 See here.

我现在不在电脑前，但如果你不明白，我可以明天看看。

编辑

这是一个如何自定义转换器的示例...

@SpringBootApplication
public class So49566278Application {

    public static void main(String[] args) {
        SpringApplication.run(So49566278Application.class, args);
    }

    @Bean
    public ApplicationRunner runner(RabbitTemplate template) {
        template.setReplyTimeout(60_000);
        return args -> {
            @SuppressWarnings("unchecked")
            List<Foo> reply = (List<Foo>) template.convertSendAndReceive("so49566278", "baz");
            System.out.println(reply);
            Foo foo = reply.get(0);
            System.out.println(foo);
        };
    }

    @RabbitListener(queues = "so49566278")
    public List<Foo> handle(String in) {
        return Collections.singletonList(new Foo(in));
    }

    @Bean
    public Queue queue() {
        return new Queue("so49566278", false, false, true);
    }

    @Bean
    public MessageConverter converter() {
        Jackson2JsonMessageConverter converter = new Jackson2JsonMessageConverter();
        converter.setJavaTypeMapper(new DefaultJackson2JavaTypeMapper() {

            @Override
            public JavaType toJavaType(MessageProperties properties) {
                JavaType javaType = super.toJavaType(properties);
                if (javaType instanceof CollectionLikeType) {
                    return TypeFactory.defaultInstance()
                            .constructCollectionLikeType(List.class, Foo.class);
                }
                else {
                    return javaType;
                }
            }

        });
        return converter;
    }

    public static class Foo {

        private String bar;

        public Foo() {
            super();
        }

        public Foo(String bar) {
            this.bar = bar;
        }

        public String getBar() {
            return this.bar;
        }

        public void setBar(String bar) {
            this.bar = bar;
        }

        @Override
        public String toString() {
            return "Foo [bar=" + this.bar + "]";
        }

    }

}

Answer 2

这种方式适用于集合没有问题。我觉得很简单：https://stackoverflow.com/a/67130566/10746857