SpringAMQP 消息转换器 - MessageConverter

栏目: Java · 发布时间: 5年前

内容简介：MessageConverter 即消息转换器我们在进行发送消息的时候，正常情况下消息体为二进制的数据方式进行传输，如果希望内部帮我们进行转换，或者指定自定义的转换器，就需要用到 MessageConverter 了。自定义常用转换器： MessageConverter, 一般来说都需要实现这个接口，然后重写以下两个方法。

MessageConverter 即消息转换器

我们在进行发送消息的时候，正常情况下消息体为二进制的数据方式进行传输，如果希望内部帮我们进行转换，或者指定自定义的转换器，就需要用到 MessageConverter 了。

自定义常用转换器： MessageConverter, 一般来说都需要实现这个接口，然后重写以下两个方法。

toMessage:  java 对象转换为 Message

fromMessage:  Message 对象转换为  Java  对象
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转换器类别：

json 转换器： jackson2JsonMessageConverter  可以进行 java 对象的转换功能

DefaultJackson2JavaTypeMapper 映射器：可以进行Java对象的映射关系

自定义二进制转换器： 比如图片类型、PDF、PPT、流媒体
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代码示例：

代码地址：  https://github.com/hmilyos/rabbitmqdemo.git  rabbitmq-api 项目下
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1. json 转换器

先创建一个 Java 实体 Order

public class Order {

    private String id;

    private String name;

    private String content;

    public Order() {
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public Order(String id, String name, String content) {
        this.id = id;
        this.name = name;
        this.content = content;
    }

    @Override
    public String toString() {
        return "Order{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", content='" + content + '\'' +
                '}';
    }
}
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接着在上一篇的 RabbitMQConfig 里面配置支持 json 格式的转换器

@Bean   //connectionFactory 也是要和最上面方法名保持一致
    public SimpleMessageListenerContainer messageContainer(ConnectionFactory connectionFactory) {
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer(connectionFactory);
        container.setQueues(queue001(), queue002(), queue003());    //监听的队列
        container.setConcurrentConsumers(1);    //当前的消费者数量
        container.setMaxConcurrentConsumers(5); //  最大的消费者数量
        container.setDefaultRequeueRejected(false); //是否重回队列
        container.setAcknowledgeMode(AcknowledgeMode.AUTO); //签收模式
        container.setExposeListenerChannel(true);
        container.setConsumerTagStrategy(new ConsumerTagStrategy() {    //消费端的标签策略
            @Override
            public String createConsumerTag(String queue) {
                return queue + "_" + UUID.randomUUID().toString();
            }
        });

        //3  支持json格式的转换器
        MessageListenerAdapter adapter = new MessageListenerAdapter(new MessageDelegate());
        adapter.setDefaultListenerMethod("consumeMessage");
        Jackson2JsonMessageConverter jackson2JsonMessageConverter = new Jackson2JsonMessageConverter();
        adapter.setMessageConverter(jackson2JsonMessageConverter);
        container.setMessageListener(adapter);
        return container;
    }
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在委派 adapter 里面声明入参为 Map 的消费方法

public void consumeMessage(Map messageBody) {
        log.info("map方法, 消息内容:" + messageBody);
    }
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功能就完成了，接着写个单元测试，注意 ContentType 一定要是 json ！！

@Test
    public void testSendJsonMessage() throws Exception {

        Order order = new Order();
        order.setId("001");
        order.setName("test1001消息订单");
        order.setContent("test1001订单描述信息");
        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(order);
        log.info("order 4 json: " + json);

        MessageProperties messageProperties = new MessageProperties();
        //这里注意一定要修改contentType为 application/json
        messageProperties.setContentType("application/json");
        Message message = new Message(json.getBytes(), messageProperties);

        rabbitTemplate.send("topic001", "spring.order", message);
    }
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运行单元测试，消息就被消费了

2. DefaultJackson2JavaTypeMapper 转换 Java 对象

messageContainer 修改成如下的

@Bean   //connectionFactory 也是要和最上面方法名保持一致
    public SimpleMessageListenerContainer messageContainer(ConnectionFactory connectionFactory) {
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer(connectionFactory);
        container.setQueues(queue001(), queue002(), queue003());    //监听的队列
        container.setConcurrentConsumers(1);    //当前的消费者数量
        container.setMaxConcurrentConsumers(5); //  最大的消费者数量
        container.setDefaultRequeueRejected(false); //是否重回队列
        container.setAcknowledgeMode(AcknowledgeMode.AUTO); //签收模式
        container.setExposeListenerChannel(true);
        container.setConsumerTagStrategy(new ConsumerTagStrategy() {    //消费端的标签策略
            @Override
            public String createConsumerTag(String queue) {
                return queue + "_" + UUID.randomUUID().toString();
            }
        });

        // 4  DefaultJackson2JavaTypeMapper & Jackson2JsonMessageConverter 支持java对象转换
        MessageListenerAdapter adapter = new MessageListenerAdapter(new MessageDelegate());
        adapter.setDefaultListenerMethod("consumeMessage");
        Jackson2JsonMessageConverter jackson2JsonMessageConverter = new Jackson2JsonMessageConverter();
        DefaultJackson2JavaTypeMapper javaTypeMapper = new DefaultJackson2JavaTypeMapper();
        jackson2JsonMessageConverter.setJavaTypeMapper(javaTypeMapper);
        adapter.setMessageConverter(jackson2JsonMessageConverter);
        container.setMessageListener(adapter);
        return container;
    }
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public void consumeMessage(Order order) {
        log.info("order对象, 消息内容, id: " + order.getId() +
                ", name: " + order.getName() +
                ", content: "+ order.getContent());
    }
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@Test
    public void testSendJavaMessage() throws Exception {
        Order order = new Order();
        order.setId("1002");
        order.setName("test1002消息订单");
        order.setContent("test1002订单描述信息");
        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(order);
        log.info("order java: " + json);

        MessageProperties messageProperties = new MessageProperties();
        //这里注意一定要修改contentType为 application/json
        messageProperties.setContentType("application/json");
        //注意这里要写你的实体类路径
        messageProperties.getHeaders().put("__TypeId__", "com.hmily.rabbitmqapi.spring.domain.Order");
        Message message = new Message(json.getBytes(), messageProperties);

        rabbitTemplate.send("topic001", "spring.order", message);
    }
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运行单元测试

报错提示：如出现 If you believe this class is safe to deserialize, please provide its name. If the serialization is only done by a trusted source, you can also enable trust all (*). 的异常提示，这是因为 Jackson 在把字节流转换为 Java 对象时发生安全提醒，粗暴的解决方式如下：

新建一个 EnableAllJackson2JavaTypeMapper 类，其继承 DefaultJackson2JavaTypeMapper 这个类，然后在这里配置允许转换哪些对象，我这是是直接允许所有。

然后在刚才的 SimpleMessageListenerContainer 里面， new EnableAllJackson2JavaTypeMapper() 改为 new EnableAllJackson2JavaTypeMapper() ，即可。

再改进一下代码，转换 2 个 Java 对象

public class Packaged {
    private String id;

    private String name;

    private String description;

    public Packaged() {
    }

    public Packaged(String id, String name, String description) {
        this.id = id;
        this.name = name;
        this.description = description;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    @Override
    public String toString() {
        return "Packaged{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", description='" + description + '\'' +
                '}';
    }
}
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messageContainer 修改成如下的

@Bean   //connectionFactory 也是要和最上面方法名保持一致
    public SimpleMessageListenerContainer messageContainer(ConnectionFactory connectionFactory) {
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer(connectionFactory);
        container.setQueues(queue001(), queue002(), queue003());    //监听的队列
        container.setConcurrentConsumers(1);    //当前的消费者数量
        container.setMaxConcurrentConsumers(5); //  最大的消费者数量
        container.setDefaultRequeueRejected(false); //是否重回队列
        container.setAcknowledgeMode(AcknowledgeMode.AUTO); //签收模式
        container.setExposeListenerChannel(true);
        container.setConsumerTagStrategy(new ConsumerTagStrategy() {    //消费端的标签策略
            @Override
            public String createConsumerTag(String queue) {
                return queue + "_" + UUID.randomUUID().toString();
            }
        });

        // 5 DefaultJackson2JavaTypeMapper & Jackson2JsonMessageConverter 支持java对象多映射转换
        MessageListenerAdapter adapter = new MessageListenerAdapter(new MessageDelegate());
        adapter.setDefaultListenerMethod("consumeMessage");
        Jackson2JsonMessageConverter jackson2JsonMessageConverter = new Jackson2JsonMessageConverter();
        DefaultJackson2JavaTypeMapper javaTypeMapper = new DefaultJackson2JavaTypeMapper();

        Map<String, Class<?>> idClassMapping = new HashMap<String, Class<?>>();
        idClassMapping.put("order", com.hmily.rabbitmqapi.spring.domain.Order.class);
        idClassMapping.put("packaged", com.hmily.rabbitmqapi.spring.domain.Packaged.class);

        javaTypeMapper.setIdClassMapping(idClassMapping);

        jackson2JsonMessageConverter.setJavaTypeMapper(javaTypeMapper);
        adapter.setMessageConverter(jackson2JsonMessageConverter);
        container.setMessageListener(adapter);
        return container;
    }
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public void consumeMessage(Packaged pack) {
        log.info("package对象, 消息内容, id: " + pack.getId() +
                ", name: " + pack.getName() +
                ", content: "+ pack.getDescription());
    }
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@Test
    public void testSendMappingMessage() throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        Order order = new Order();
        order.setId("1001");
        order.setName("1001订单消息");
        order.setContent("1001订单描述信息");
        String json1 = mapper.writeValueAsString(order);
        log.info("order java: " + json1);

        MessageProperties messageProperties1 = new MessageProperties();
        //这里注意一定要修改contentType为 application/json
        messageProperties1.setContentType("application/json");
        messageProperties1.getHeaders().put("__TypeId__", "order");
        Message message1 = new Message(json1.getBytes(), messageProperties1);
        rabbitTemplate.send("topic001", "spring.order", message1);

        Packaged pack = new Packaged();
        pack.setId("1002");
        pack.setName("1002包裹消息");
        pack.setDescription("1002包裹描述信息");
        String json2 = mapper.writeValueAsString(pack);
        log.info("pack  java: " + json2);

        MessageProperties messageProperties2 = new MessageProperties();
        //这里注意一定要修改contentType为 application/json
        messageProperties2.setContentType("application/json");
        messageProperties2.getHeaders().put("__TypeId__", "packaged");
        Message message2 = new Message(json2.getBytes(), messageProperties2);
        rabbitTemplate.send("topic001", "spring.pack", message2);
    }
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注意这里面就不是写类的路径了，而是写刚才起的别名了

因为junitTest的关系，它发送完就关闭了，还有一条消息没被消费

可以上管控台确认一下

这时候直接运行一下我们项目 RabbitmqApiApplication ，就把刚才剩余的那条消息消费了

3. 二进制转换器

先写转换处理

public class ImageMessageConverter implements MessageConverter {

    private static final Logger log = LoggerFactory.getLogger(ImageMessageConverter.class);

	@Override
	public Message toMessage(Object object, MessageProperties messageProperties) throws MessageConversionException {
		throw new MessageConversionException(" convert error ! ");
	}

	@Override
	public Object fromMessage(Message message) throws MessageConversionException {
		log.info("-----------Image MessageConverter----------");
		
		Object _extName = message.getMessageProperties().getHeaders().get("extName");
		String extName = _extName == null ? "png" : _extName.toString();
		
		byte[] body = message.getBody();
		String fileName = UUID.randomUUID().toString();
		String path = "G:/test/file/new/" + fileName + "." + extName;
		File f = new File(path);
		try {
			Files.copy(new ByteArrayInputStream(body), f.toPath());
		} catch (IOException e) {
			e.printStackTrace();
		}
		return f;
	}

}

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消息接收

public void consumeMessage(File file) {
        log.info("文件对象 方法, 消息内容:" + file.getName());
    }
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声明一个全局的转换器

@Bean   //connectionFactory 也是要和最上面方法名保持一致
    public SimpleMessageListenerContainer messageContainer(ConnectionFactory connectionFactory) {
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer(connectionFactory);
        container.setQueues(queue001(), queue002(), queue003());    //监听的队列
        container.setConcurrentConsumers(1);    //当前的消费者数量
        container.setMaxConcurrentConsumers(5); //  最大的消费者数量
        container.setDefaultRequeueRejected(false); //是否重回队列
        container.setAcknowledgeMode(AcknowledgeMode.AUTO); //签收模式
        container.setExposeListenerChannel(true);
        container.setConsumerTagStrategy(new ConsumerTagStrategy() {    //消费端的标签策略
            @Override
            public String createConsumerTag(String queue) {
                return queue + "_" + UUID.randomUUID().toString();
            }
        });

        // 6 ext convert
        MessageListenerAdapter adapter = new MessageListenerAdapter(new MessageDelegate());
        adapter.setDefaultListenerMethod("consumeMessage");

        //全局的转换器:
        ContentTypeDelegatingMessageConverter convert = new ContentTypeDelegatingMessageConverter();

        TextMessageConverter textConvert = new TextMessageConverter();
        convert.addDelegate("text", textConvert);
        convert.addDelegate("html/text", textConvert);
        convert.addDelegate("xml/text", textConvert);
        convert.addDelegate("text/plain", textConvert);

        Jackson2JsonMessageConverter jsonConvert = new Jackson2JsonMessageConverter();
        convert.addDelegate("json", jsonConvert);
        convert.addDelegate("application/json", jsonConvert);

        ImageMessageConverter imageConverter = new ImageMessageConverter();
        convert.addDelegate("image/png", imageConverter);
        convert.addDelegate("image", imageConverter);

        PDFMessageConverter pdfConverter = new PDFMessageConverter();
        convert.addDelegate("application/pdf", pdfConverter);


        adapter.setMessageConverter(convert);
        container.setMessageListener(adapter);

        return container;
    }
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编写单元测试来测试图片

@Test
    public void testSendExtConverterMessage() throws Exception {
        byte[] body = Files.readAllBytes(Paths.get("G:/test/file", "1001.png"));
        MessageProperties messageProperties = new MessageProperties();
        messageProperties.setContentType("image/png");
        messageProperties.getHeaders().put("extName", "png");
        Message message = new Message(body, messageProperties);
        rabbitTemplate.send("", "image_queue", message);
    }
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原图片的本地文件夹路径

运行测试后，图片生成到指定的目录下

这次来试试PDF

public class PDFMessageConverter implements MessageConverter {

    private static final Logger log = LoggerFactory.getLogger(PDFMessageConverter.class);

	@Override
	public Message toMessage(Object object, MessageProperties messageProperties) throws MessageConversionException {
		throw new MessageConversionException(" convert error ! ");
	}

	@Override
	public Object fromMessage(Message message) throws MessageConversionException {
		log.info("-----------PDF MessageConverter----------");
		
		byte[] body = message.getBody();
		String fileName = UUID.randomUUID().toString();
		String path = "G:/test/file/new/" + fileName + ".pdf";
		File f = new File(path);
		try {
			Files.copy(new ByteArrayInputStream(body), f.toPath());
		} catch (IOException e) {
			e.printStackTrace();
		}
		return f;
	}

}
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@Test
    public void testSendExtConverterMessage() throws Exception {
//        byte[] body = Files.readAllBytes(Paths.get("G:/test/file", "1001.png"));
//        MessageProperties messageProperties = new MessageProperties();
//        messageProperties.setContentType("image/png");
//        messageProperties.getHeaders().put("extName", "png");
//        Message message = new Message(body, messageProperties);
//        rabbitTemplate.send("", "image_queue", message);

        byte[] body = Files.readAllBytes(Paths.get("G:/test/file", "AliTech101_RD.pdf"));
        MessageProperties messageProperties = new MessageProperties();
        messageProperties.setContentType("application/pdf");
        Message message = new Message(body, messageProperties);
        rabbitTemplate.send("", "pdf_queue", message);
    }
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验证 PDF 的处理是否成功了。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持码农网

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