rabbitmq学习8:spring-amqp的重要类的认识
对于大多数应用来说都做了与spring整合，对于rabbitmq来说。也有与spring的整合。可能通过spring的官网找到spring-amqp项目下载。spring-amqp项目包括三个子项目：spring-amqp、spring-erlang、spring-rabbit.
下面来认识一下spring-amqp中的几个重要类；以spring-amqp-1.0.0.M3版本为例
1、Message : Spring AMQP定义的Message类是AMQP域模型中代表之一。Message类封装了body(消息BODY)和properties（消息属性） 。使得这个API看起来很简单。Message类定义如下：
public class Message {
private final MessageProperties messageProperties;
private final byte[] body;
public Message(byte[] body, MessageProperties messageProperties) {
this.body = body;
this.messageProperties = messageProperties;
}
public byte[] getBody() {
return this.body;
}
public MessageProperties getMessageProperties() {
return this.messageProperties;
}
} 其中MessageProperties类中定义了例如messageId、timestamp、contentType等属性。这此属性可以扩展到用户通过setHeader(String key, Object value)方法来自定义“headers”。
2、Exchange
Exchange接口代表一个AMQP的Exchange，决定消息生产者发送消息。每个Exchange都包括一个特定的唯一名字的虚拟主机的代理和一些其他属性。
public interface Exchange {
String getName();
String getType();
boolean isDurable();
boolean isAutoDelete();
Map<String, Object> getArguments();
} 其中 AbstractExchange类实现了Exchange类。而DirectExchange、TopicExchange、FanoutExchang、HeadersExchange四个类继承AbstractExchange。并重写了getType()类。根据各自相对应的Exchange类型。DirectExchange、TopicExchange、FanoutExchang、HeadersExchange分别对应的类型为direct,topic,fanout,headers.对应Exchange与routingkey的判定关系在前面的章节中已学习了！
3、Queue
Queue类是消息消费者接收消息中重要的一个组成部分。通过与Exchange判定来肯定消费者所接收的消息。伪代码如下：
public class Queue {
private final String name;
private volatile boolean durable;
private volatile boolean exclusive;
private volatile boolean autoDelete;
private volatile Map<String, Object> arguments;
public Queue(String name) {
this.name = name;
}
// Getters and Setters omitted for brevity 其中name表示队列的名称、durable表示持久性。true表示是。exclusive表示独占性。由于在AmqpTemplate中提供一个方法来得到唯一的队列。这个队列可能是一个”reply-to“地址或者其他信息，因此一般exclusive和autoDelete一般设定为true.
4、Binding
Bingding类通过多种构造参数来判定Exchange,Queue,routingkey;例如
Binding(Queue queue, FanoutExchange exchange)
Binding(Queue queue, HeadersExchange exchange, Map<String, Object> arguments)
Binding(Queue queue, DirectExchange exchange)
Binding(Queue queue, DirectExchange exchange, String routingKey)
Binding(Queue queue, TopicExchange exchange, String routingKey)
5、AmqpTemplate
AmqpTemplate是用来发送消息的模板类
public interface AmqpTemplate {
// send methods for messages
void send(Message message) throws AmqpException;
void send(String routingKey, Message message) throws AmqpException;
void send(String exchange, String routingKey, Message message) throws AmqpException;
// send methods with conversion
void convertAndSend(Object message) throws AmqpException;
void convertAndSend(String routingKey, Object message) throws AmqpException;
void convertAndSend(String exchange, String routingKey, Object message) throws AmqpException;
void convertAndSend(Object message, MessagePostProcessor messagePostProcessor) throws AmqpException;
void convertAndSend(String routingKey, Object message, MessagePostProcessor messagePostProcessor) throws AmqpException;
void convertAndSend(String exchange, String routingKey, Object message, MessagePostProcessor messagePostProcessor) throws AmqpException;
// receive methods for messages
Message receive() throws AmqpException;
Message receive(String queueName) throws AmqpException;
// receive methods with conversion
Object receiveAndConvert() throws AmqpException;
Object receiveAndConvert(String queueName) throws AmqpException;
// send and receive methods for messages
Message sendAndReceive(Message message) throws AmqpException;
Message sendAndReceive(String routingKey, Message message) throws AmqpException;
Message sendAndReceive(String exchange, String routingKey, Message message) throws AmqpException;
// send and receive methods with conversion
Object convertSendAndReceive(Object message) throws AmqpException;
Object convertSendAndReceive(String routingKey, Object message) throws AmqpException;
Object convertSendAndReceive(String exchange, String routingKey, Object message) throws AmqpException;
} 6、AmqpAdmin和RabbitAdmin
用户配置Queue、Exchange、Binding的代理类。代理类会自动声明或创建这些配置信息。
下面这个类用于异步接收消息的处理类
7、MessageConverter 消息转换器类
8、SimpleMessageListenerContainer 监听消息容器类