7.rabbitmq之GSON

下面我们通过一个实例看一下rabbit的使用。

1.实现一个消息监听器ReceiveMessageListener.Java

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1. package org.springframework.amqp.core;  
2.   
3. /** 
4.  * Listener interface to receive asynchronous delivery of Amqp Messages. 
5.  * 
6.  * @author Mark Pollack 
7.  */  
8. public interface MessageListener {  
9.   
10.     void onMessage(Message message);  
11.   
12. }  

2.消费者配置Consumer.xml

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1. <?xml version="1.0" encoding="UTF-8"?>  
2. <beans xmlns="http://www.springframework.org/schema/beans"  
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
4.        xmlns:context="http://www.springframework.org/schema/context"  
5.        xmlns:rabbit="http://www.springframework.org/schema/rabbit"  
6.        xsi:schemaLocation="  
7.             http://www.springframework.org/schema/beans  
8.                 http://www.springframework.org/schema/beans/spring-beans.xsd  
9.             http://www.springframework.org/schema/context  
10.                 http://www.springframework.org/schema/context/spring-context.xsd  
11.             http://www.springframework.org/schema/rabbit  
12.                 http://www.springframework.org/schema/rabbit/spring-rabbit-1.0.xsd">  
13.    
14.    <!-- 连接服务配置  -->  
15.     <rabbit:connection-factory id="connectionFactory" host="192.168.36.102" username="admin"  
16.         password="admin" port="5672" virtual-host="/"  channel-cache-size="5" />  
17.            
18.    <rabbit:admin connection-factory="connectionFactory"/>  
19.      
20.    <!-- queue 队列声明-->  
21.    <rabbit:queue durable="true" auto-delete="false" exclusive="false" name="spring.queue.tag"/>  
22.       
23.       
24.    <!-- exchange queue binging key 绑定 -->  
25.     <rabbit:direct-exchange name="spring.queue.exchange" durable="true" auto-delete="false">  
26.         <rabbit:bindings>  
27.             <rabbit:binding queue="spring.queue.tag" key="spring.queue.tag.key"/>  
28.         </rabbit:bindings>  
29.     </rabbit:direct-exchange>  
30.       
31.     <bean id="receiveMessageListener"  
32.         class="cn.slimsmart.rabbitmq.demo.spring.tag.ReceiveMessageListener" />  
33.        
34.     <!-- queue litener  观察 监听模式 当有消息到达时会通知监听在对应的队列上的监听对象-->  
35.     <rabbit:listener-container connection-factory="connectionFactory" acknowledge="auto" >  
36.         <rabbit:listener queues="spring.queue.tag" ref="receiveMessageListener" />  
37.     </rabbit:listener-container>  
38. </beans>  

3.生产者配置Producer.xml

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1. <?xml version="1.0" encoding="UTF-8"?>  
2. <beans xmlns="http://www.springframework.org/schema/beans"  
3.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"  
4.     xmlns:rabbit="http://www.springframework.org/schema/rabbit"  
5.     xsi:schemaLocation="  
6.             http://www.springframework.org/schema/beans  
7.                 http://www.springframework.org/schema/beans/spring-beans.xsd  
8.             http://www.springframework.org/schema/context  
9.                 http://www.springframework.org/schema/context/spring-context.xsd  
10.             http://www.springframework.org/schema/rabbit  
11.                 http://www.springframework.org/schema/rabbit/spring-rabbit-1.0.xsd">  
12.   
13.     <!-- 连接服务配置 -->  
14.     <rabbit:connection-factory id="connectionFactory"  
15.         host="192.168.36.102" username="admin" password="admin" port="5672"  
16.         virtual-host="/" channel-cache-size="5" />  
17.   
18.     <rabbit:admin connection-factory="connectionFactory" />  
19.   
20.     <!-- queue 队列声明 -->  
21.     <rabbit:queue  durable="true"  
22.         auto-delete="false" exclusive="false" name="spring.queue.tag" />  
23.   
24.   
25.     <!-- exchange queue binging key 绑定 -->  
26.     <rabbit:direct-exchange name="spring.queue.exchange"  
27.         durable="true" auto-delete="false">  
28.         <rabbit:bindings>  
29.             <rabbit:binding queue="spring.queue.tag" key="spring.queue.tag.key" />  
30.         </rabbit:bindings>  
31.     </rabbit:direct-exchange>  
32.   
33.     <!-- spring amqp默认的是jackson 的一个插件,目的将生产者生产的数据转换为json存入消息队列，由于Gson的速度快于jackson,这里替换为Gson的一个实现 -->  
34.     <bean id="jsonMessageConverter"  
35.         class="cn.slimsmart.rabbitmq.demo.spring.tag.Gson2JsonMessageConverter" />  
36.   
37.     <!-- spring template声明 -->  
38.     <rabbit:template id="amqpTemplate" exchange="spring.queue.exchange"  routing-key="spring.queue.tag.key"  
39.         connection-factory="connectionFactory" message-converter="jsonMessageConverter" />  
40. </beans>  

4.消费者启动类ConsumerMain.java

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1. package cn.slimsmart.rabbitmq.demo.spring.tag;  
2.   
3. import org.springframework.context.support.ClassPathXmlApplicationContext;  
4.   
5. public class ConsumerMain {  
6.   
7.     public static void main(String[] args) {  
8.         new ClassPathXmlApplicationContext("Consumer.xml");    
9.     }  
10. }  

5.生产者启动类ProducerMain.java

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1. package cn.slimsmart.rabbitmq.demo.spring.tag;  
2.   
3. import org.springframework.amqp.core.AmqpTemplate;  
4. import org.springframework.amqp.rabbit.core.RabbitTemplate;  
5. import org.springframework.context.ApplicationContext;  
6. import org.springframework.context.support.ClassPathXmlApplicationContext;  
7.   
8. public class ProducerMain {  
9.       
10.     public static void main(String[] args) {  
11.         ApplicationContext context = new ClassPathXmlApplicationContext("Producer.xml");    
12.         AmqpTemplate amqpTemplate = context.getBean(RabbitTemplate.class);     
13.         User user = new User();  
14.         user.setName("niuniu");  
15.         amqpTemplate.convertAndSend(user);  
16.     }  
17. }  

先启动消费者，监听接收消息，再启动生产者发送消息。

输出： data :{"name":"niuniu"}

如下4中转发器类型标签

rabbit:fanout-exchange

rabbit:direct-exchange

rabbit:topic-exchange

rabbit:headers-exchange

RabbitMQ已经实现了Jackson的消息转换（Jackson2JsonMessageConverter），由于考虑到效率，如下使用Gson实现消息转换。

如下消息的转换类的接口MessageConverter，Jackson2JsonMessageConverter的父类AbstractJsonMessageConverter针对json转换的基类。

我们实现Gson2JsonMessageConverter转换类也继承AbstractJsonMessageConverter。

引入Gson的pom

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1. <dependency>  
2.             <groupId>com.google.code.gson</groupId>  
3.             <artifactId>gson</artifactId>  
4.             <version>2.3</version>  
5.         </dependency>  

转换类实现如下：

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1. package cn.slimsmart.rabbitmq.demo.spring.tag;  
2.   
3. import java.io.IOException;  
4. import java.io.UnsupportedEncodingException;  
5.   
6. import org.apache.commons.logging.Log;  
7. import org.apache.commons.logging.LogFactory;  
8. import org.springframework.amqp.core.Message;  
9. import org.springframework.amqp.core.MessageProperties;  
10. import org.springframework.amqp.support.converter.AbstractJsonMessageConverter;  
11. import org.springframework.amqp.support.converter.ClassMapper;  
12. import org.springframework.amqp.support.converter.DefaultClassMapper;  
13. import org.springframework.amqp.support.converter.MessageConversionException;  
14.   
15. import com.google.gson.Gson;  
16.   
17. public class Gson2JsonMessageConverter extends AbstractJsonMessageConverter {  
18.       
19.     private static Log log = LogFactory.getLog(Gson2JsonMessageConverter.class);  
20.       
21.     private static  ClassMapper classMapper =  new DefaultClassMapper();  
22.   
23.     private static Gson gson = new Gson();  
24.   
25.     public Gson2JsonMessageConverter() {  
26.         super();  
27.     }  
28.   
29.     @Override  
30.     protected Message createMessage(Object object,  
31.             MessageProperties messageProperties) {  
32.         byte[] bytes = null;  
33.         try {  
34.             String jsonString = gson.toJson(object);  
35.             bytes = jsonString.getBytes(getDefaultCharset());  
36.         }  
37.         catch (IOException e) {  
38.             throw new MessageConversionException(  
39.                     "Failed to convert Message content", e);  
40.         }  
41.         messageProperties.setContentType(MessageProperties.CONTENT_TYPE_JSON);  
42.         messageProperties.setContentEncoding(getDefaultCharset());  
43.         if (bytes != null) {  
44.             messageProperties.setContentLength(bytes.length);  
45.         }  
46.         classMapper.fromClass(object.getClass(),messageProperties);  
47.         return new Message(bytes, messageProperties);  
48.     }  
49.   
50.     @Override  
51.     public Object fromMessage(Message message)  
52.             throws MessageConversionException {  
53.         Object content = null;  
54.         MessageProperties properties = message.getMessageProperties();  
55.         if (properties != null) {  
56.             String contentType = properties.getContentType();  
57.             if (contentType != null && contentType.contains("json")) {  
58.                 String encoding = properties.getContentEncoding();  
59.                 if (encoding == null) {  
60.                     encoding = getDefaultCharset();  
61.                 }  
62.                 try {  
63.                         Class<?> targetClass = getClassMapper().toClass(  
64.                                 message.getMessageProperties());  
65.                         content = convertBytesToObject(message.getBody(),  
66.                                 encoding, targetClass);  
67.                 }  
68.                 catch (IOException e) {  
69.                     throw new MessageConversionException(  
70.                             "Failed to convert Message content", e);  
71.                 }  
72.             }  
73.             else {  
74.                 log.warn("Could not convert incoming message with content-type ["  
75.                         + contentType + "]");  
76.             }  
77.         }  
78.         if (content == null) {  
79.             content = message.getBody();  
80.         }  
81.         return content;  
82.     }  
83.   
84.     private Object convertBytesToObject(byte[] body, String encoding,  
85.             Class<?> clazz) throws UnsupportedEncodingException {  
86.         String contentAsString = new String(body, encoding);  
87.         return gson.fromJson(contentAsString, clazz);  
88.     }  
89. }