怎么在Java项目中利用rabbitMQ实现一个消息收发功能？相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
java实现rAMQP，即Advanced Message Queuing Protocol，高级消息队列协议，是应用层协议的一个开放标准，为面向消息的中间件设计。消息中间件主要用于组件之间的解耦，消息的发送者无需知道消息使用者的存在，反之亦然。
AMQP的主要特征是面向消息、队列、路由（包括点对点和发布/订阅）、可靠性、安全。
RabbitMQ是一个开源的AMQP实现，服务器端用Erlang语言编写，支持多种客户端，如：Python、Ruby、.NET、Java、JMS、C、PHP、ActionScript、XMPP、STOMP等，支持AJAX。用于在分布式系统中存储转发消息，在易用性、扩展性、高可用性等方面表现不俗。
本文不介绍amqp和rabbitmq相关知识，请自行网上查阅
本文是基于spring-rabbit中间件来实现消息的发送接受功能
see http://www.rabbitmq.com/tutorials/tutorial-one-java.html
see http://www.springsource.org/spring-amqp
Java编程通过操作rabbitMQ消息的收发实现代码如下：
<!-- for rabbitmq --> <dependency> <groupId>com.rabbitmq</groupId> <artifactId>amqp-client</artifactId> <version>2.8.2</version> </dependency> <dependency> <groupId>org.springframework.amqp</groupId> <artifactId>spring-amqp</artifactId> <version>1.1.1.RELEASE</version> </dependency> <dependency> <groupId>org.springframework.amqp</groupId> <artifactId>spring-rabbit</artifactId> <version>1.1.1.RELEASE</version> </dependency> <dependency> <groupId>com.caucho</groupId> <artifactId>hessian</artifactId> <version>4.0.7</version> </dependency> </dependencies>
首先我们需要一个用来在app和rabbitmq之间传递消息的持有对象
public class EventMessage implements Serializable{
private String queueName;
private String exchangeName;
private byte[] eventData;
public EventMessage(String queueName, String exchangeName, byte[] eventData) {
this.queueName = queueName;
this.exchangeName = exchangeName;
this.eventData = eventData;
}
public EventMessage() {
}
public String getQueueName() {
return queueName;
}
public String getExchangeName() {
return exchangeName;
}
public byte[] getEventData() {
return eventData;
}
@Override
public String toString() {
return "EopEventMessage [queueName=" + queueName + ", exchangeName="
+ exchangeName + ", eventData=" + Arrays.toString(eventData)
+ "]";
}
}为了可以发送和接受这个消息持有对象，我们还需要需要一个用来序列化和反序列化的工厂
public interface CodecFactory {
byte[] serialize(Object obj) throws IOException;
Object deSerialize(byte[] in) throws IOException;
}下面是编码解码的实现类，用了hessian来实现，大家可以自行选择序列化方式
public class HessionCodecFactory implements CodecFactory {
private final Logger logger = Logger.getLogger(HessionCodecFactory.class);
@Override
public byte[] serialize(Object obj) throws IOException {
ByteArrayOutputStream baos = null;
HessianOutput output = null;
try {
baos = new ByteArrayOutputStream(1024);
output = new HessianOutput(baos);
output.startCall();
output.writeObject(obj);
output.completeCall();
} catch (final IOException ex) {
throw ex;
} finally {
if (output != null) {
try {
baos.close();
} catch (final IOException ex) {
this.logger.error("Failed to close stream.", ex);
}
}
}
return baos != null ? baos.toByteArray() : null;
}
@Override
public Object deSerialize(byte[] in) throws IOException {
Object obj = null;
ByteArrayInputStream bais = null;
HessianInput input = null;
try {
bais = new ByteArrayInputStream(in);
input = new HessianInput(bais);
input.startReply();
obj = input.readObject();
input.completeReply();
} catch (final IOException ex) {
throw ex;
} catch (final Throwable e) {
this.logger.error("Failed to decode object.", e);
} finally {
if (input != null) {
try {
bais.close();
} catch (final IOException ex) {
this.logger.error("Failed to close stream.", ex);
}
}
}
return obj;
}
}接下来就先实现发送功能，新增一个接口专门用来实现发送功能
public interface EventTemplate {
void send(String queueName,String exchangeName,Object eventContent) throws SendRefuseException;
void send(String queueName,String exchangeName,Object eventContent,CodecFactory codecFactory) throws SendRefuseException;
}SendRefuseException是自定义的发送失败异常类
下面是它的实现类，主要的任务就是将数据转换为EventMessage
public class DefaultEventTemplate implements EventTemplate {
private static final Logger logger = Logger.getLogger(DefaultEventTemplate.class);
private AmqpTemplate eventAmqpTemplate;
private CodecFactory defaultCodecFactory;
// private DefaultEventController eec;
// public DefaultEventTemplate(AmqpTemplate eopAmqpTemplate,
// CodecFactory defaultCodecFactory, DefaultEventController eec) {
// this.eventAmqpTemplate = eopAmqpTemplate;
// this.defaultCodecFactory = defaultCodecFactory;
// this.eec = eec;
// }
public DefaultEventTemplate(AmqpTemplate eopAmqpTemplate,CodecFactory defaultCodecFactory) {
this.eventAmqpTemplate = eopAmqpTemplate;
this.defaultCodecFactory = defaultCodecFactory;
}
@Override
public void send(String queueName, String exchangeName, Object eventContent)
throws SendRefuseException {
this.send(queueName, exchangeName, eventContent, defaultCodecFactory);
}
@Override
public void send(String queueName, String exchangeName, Object eventContent,
CodecFactory codecFactory) throws SendRefuseException {
if (StringUtils.isEmpty(queueName) || StringUtils.isEmpty(exchangeName)) {
throw new SendRefuseException("queueName exchangeName can not be empty.");
}
// if (!eec.beBinded(exchangeName, queueName))
// eec.declareBinding(exchangeName, queueName);
byte[] eventContentBytes = null;
if (codecFactory == null) {
if (eventContent == null) {
logger.warn("Find eventContent is null,are you sure...");
} else {
throw new SendRefuseException(
"codecFactory must not be null ,unless eventContent is null");
}
} else {
try {
eventContentBytes = codecFactory.serialize(eventContent);
} catch (IOException e) {
throw new SendRefuseException(e);
}
}
// 构造成Message
EventMessage msg = new EventMessage(queueName, exchangeName,
eventContentBytes);
try {
eventAmqpTemplate.convertAndSend(exchangeName, queueName, msg);
} catch (AmqpException e) {
logger.error("send event fail. Event Message : [" + eventContent + "]", e);
throw new SendRefuseException("send event fail", e);
}
}
}注释的地方稍后会用到，主要是防止数据数据发送的地方没有事先声明
然后我们再实现接受消息
首先我们需要一个消费接口，所有的消费程序都实现这个类
public interface EventProcesser {
public void process(Object e);
}为了能够将不同类型的消息交由对应的程序来处理，我们还需要一个消息处理适配器
/**
* MessageListenerAdapter的Pojo
* <p>消息处理适配器，主要功能：</p>
* <p>1、将不同的消息类型绑定到对应的处理器并本地缓存，如将queue01+exchange01的消息统一交由A处理器来出来</p>
* <p>2、执行消息的消费分发，调用相应的处理器来消费属于它的消息</p>
*
*/
public class MessageAdapterHandler {
private static final Logger logger = Logger.getLogger(MessageAdapterHandler.class);
private ConcurrentMap<String, EventProcessorWrap> epwMap;
public MessageAdapterHandler() {
this.epwMap = new ConcurrentHashMap<String, EventProcessorWrap>();
}
public void handleMessage(EventMessage eem) {
logger.debug("Receive an EventMessage: [" + eem + "]");
// 先要判断接收到的message是否是空的，在某些异常情况下，会产生空值
if (eem == null) {
logger.warn("Receive an null EventMessage, it may product some errors, and processing message is canceled.");
return;
}
if (StringUtils.isEmpty(eem.getQueueName()) || StringUtils.isEmpty(eem.getExchangeName())) {
logger.warn("The EventMessage's queueName and exchangeName is empty, this is not allowed, and processing message is canceled.");
return;
}
// 解码，并交给对应的EventHandle执行
EventProcessorWrap eepw = epwMap.get(eem.getQueueName()+"|"+eem.getExchangeName());
if (eepw == null) {
logger.warn("Receive an EopEventMessage, but no processor can do it.");
return;
}
try {
eepw.process(eem.getEventData());
} catch (IOException e) {
logger.error("Event content can not be Deserialized, check the provided CodecFactory.",e);
return;
}
}
protected void add(String queueName, String exchangeName, EventProcesser processor,CodecFactory codecFactory) {
if (StringUtils.isEmpty(queueName) || StringUtils.isEmpty(exchangeName) || processor == null || codecFactory == null) {
throw new RuntimeException("queueName and exchangeName can not be empty,and processor or codecFactory can not be null. ");
}
EventProcessorWrap epw = new EventProcessorWrap(codecFactory,processor);
EventProcessorWrap oldProcessorWrap = epwMap.putIfAbsent(queueName + "|" + exchangeName, epw);
if (oldProcessorWrap != null) {
logger.warn("The processor of this queue and exchange exists, and the new one can't be add");
}
}
protected Set<String> getAllBinding() {
Set<String> keySet = epwMap.keySet();
return keySet;
}
protected static class EventProcessorWrap {
private CodecFactory codecFactory;
private EventProcesser eep;
protected EventProcessorWrap(CodecFactory codecFactory,
EventProcesser eep) {
this.codecFactory = codecFactory;
this.eep = eep;
}
public void process(byte[] eventData) throws IOException{
Object obj = codecFactory.deSerialize(eventData);
eep.process(obj);
}
}
}这是正常情况下的消息处理方式，如果rabbitmq消息接受发生异常，也要监控到，新增一个消费类专门用来处理错误异常的消息
public class MessageErrorHandler implements ErrorHandler{
private static final Logger logger = Logger.getLogger(MessageErrorHandler.class);
@Override
public void handleError(Throwable t) {
logger.error("RabbitMQ happen a error:" + t.getMessage(), t);
}
}接下来我们可能需要一个专门配置和rabbitmq通信的一些信息，比如地址，端口等信息
public class EventControlConfig {
private final static int DEFAULT_PORT = 5672;
private final static String DEFAULT_USERNAME = "guest";
private final static String DEFAULT_PASSWORD = "guest";
private final static int DEFAULT_PROCESS_THREAD_NUM = Runtime.getRuntime().availableProcessors() * 2;
private static final int PREFETCH_SIZE = 1;
private String serverHost ;
private int port = DEFAULT_PORT;
private String username = DEFAULT_USERNAME;
private String password = DEFAULT_PASSWORD;
private String virtualHost;
/**
* 和rabbitmq建立连接的超时时间
*/
private int connectionTimeout = 0;
/**
* 事件消息处理线程数，默认是 CPU核数 * 2
*/
private int eventMsgProcessNum;
/**
* 每次消费消息的预取值
*/
private int prefetchSize;
public EventControlConfig(String serverHost) {
this(serverHost,DEFAULT_PORT,DEFAULT_USERNAME,DEFAULT_PASSWORD,null,0,DEFAULT_PROCESS_THREAD_NUM,DEFAULT_PROCESS_THREAD_NUM,new HessionCodecFactory());
}
public EventControlConfig(String serverHost, int port, String username,
String password, String virtualHost, int connectionTimeout,
int eventMsgProcessNum,int prefetchSize,CodecFactory defaultCodecFactory) {
this.serverHost = serverHost;
this.port = port>0?port:DEFAULT_PORT;
this.username = username;
this.password = password;
this.virtualHost = virtualHost;
this.connectionTimeout = connectionTimeout>0?connectionTimeout:0;
this.eventMsgProcessNum = eventMsgProcessNum>0?eventMsgProcessNum:DEFAULT_PROCESS_THREAD_NUM;
this.prefetchSize = prefetchSize>0?prefetchSize:PREFETCH_SIZE;
}
public String getServerHost() {
return serverHost;
}
public int getPort() {
return port;
}
public String getUsername() {
return username;
}
public String getPassword() {
return password;
}
public String getVirtualHost() {
return virtualHost;
}
public int getConnectionTimeout() {
return connectionTimeout;
}
public int getEventMsgProcessNum() {
return eventMsgProcessNum;
}
public int getPrefetchSize() {
return prefetchSize;
}
}具体的发送、接受程序已经好了，接下来也是最重要的就是管理控制和rabbitmq的通信
public interface EventController {
/**
* 控制器启动方法
*/
void start();
/**
* 获取发送模版
*/
EventTemplate getEopEventTemplate();
/**
* 绑定消费程序到对应的exchange和queue
*/
EventController add(String queueName, String exchangeName, EventProcesser eventProcesser);
/*in map, the key is queue name, but value is exchange name*/
EventController add(Map<String,String> bindings, EventProcesser eventProcesser);
}它的实现类如下：
/**
* 和rabbitmq通信的控制器，主要负责：
* <p>1、和rabbitmq建立连接</p>
* <p>2、声明exChange和queue以及它们的绑定关系</p>
* <p>3、启动消息监听容器，并将不同消息的处理者绑定到对应的exchange和queue上</p>
* <p>4、持有消息发送模版以及所有exchange、queue和绑定关系的本地缓存</p>
* @author yangyong
*
*/
public class DefaultEventController implements EventController {
private CachingConnectionFactory rabbitConnectionFactory;
private EventControlConfig config;
private RabbitAdmin rabbitAdmin;
private CodecFactory defaultCodecFactory = new HessionCodecFactory();
private SimpleMessageListenerContainer msgListenerContainer; // rabbitMQ msg listener container
private MessageAdapterHandler msgAdapterHandler = new MessageAdapterHandler();
private MessageConverter serializerMessageConverter = new SerializerMessageConverter(); // 直接指定
//queue cache, key is exchangeName
private Map<String, DirectExchange> exchanges = new HashMap<String,DirectExchange>();
//queue cache, key is queueName
private Map<String, Queue> queues = new HashMap<String, Queue>();
//bind relation of queue to exchange cache, value is exchangeName | queueName
private Set<String> binded = new HashSet<String>();
private EventTemplate eventTemplate; // 给App使用的Event发送客户端
private AtomicBoolean isStarted = new AtomicBoolean(false);
private static DefaultEventController defaultEventController;
public synchronized static DefaultEventController getInstance(EventControlConfig config){
if(defaultEventController==null){
defaultEventController = new DefaultEventController(config);
}
return defaultEventController;
}
private DefaultEventController(EventControlConfig config){
if (config == null) {
throw new IllegalArgumentException("Config can not be null.");
}
this.config = config;
initRabbitConnectionFactory();
// 初始化AmqpAdmin
rabbitAdmin = new RabbitAdmin(rabbitConnectionFactory);
// 初始化RabbitTemplate
RabbitTemplate rabbitTemplate = new RabbitTemplate(rabbitConnectionFactory);
rabbitTemplate.setMessageConverter(serializerMessageConverter);
eventTemplate = new DefaultEventTemplate(rabbitTemplate,defaultCodecFactory, this);
}
/**
* 初始化rabbitmq连接
*/
private void initRabbitConnectionFactory() {
rabbitConnectionFactory = new CachingConnectionFactory();
rabbitConnectionFactory.setHost(config.getServerHost());
rabbitConnectionFactory.setChannelCacheSize(config.getEventMsgProcessNum());
rabbitConnectionFactory.setPort(config.getPort());
rabbitConnectionFactory.setUsername(config.getUsername());
rabbitConnectionFactory.setPassword(config.getPassword());
if (!StringUtils.isEmpty(config.getVirtualHost())) {
rabbitConnectionFactory.setVirtualHost(config.getVirtualHost());
}
}
/**
* 注销程序
*/
public synchronized void destroy() throws Exception {
if (!isStarted.get()) {
return;
}
msgListenerContainer.stop();
eventTemplate = null;
rabbitAdmin = null;
rabbitConnectionFactory.destroy();
}
@Override
public void start() {
if (isStarted.get()) {
return;
}
Set<String> mapping = msgAdapterHandler.getAllBinding();
for (String relation : mapping) {
String[] relaArr = relation.split("\\|");
declareBinding(relaArr[1], relaArr[0]);
}
initMsgListenerAdapter();
isStarted.set(true);
}
/**
* 初始化消息监听器容器
*/
private void initMsgListenerAdapter(){
MessageListener listener = new MessageListenerAdapter(msgAdapterHandler,serializerMessageConverter);
msgListenerContainer = new SimpleMessageListenerContainer();
msgListenerContainer.setConnectionFactory(rabbitConnectionFactory);
msgListenerContainer.setAcknowledgeMode(AcknowledgeMode.AUTO);
msgListenerContainer.setMessageListener(listener);
msgListenerContainer.setErrorHandler(new MessageErrorHandler());
msgListenerContainer.setPrefetchCount(config.getPrefetchSize()); // 设置每个消费者消息的预取值
msgListenerContainer.setConcurrentConsumers(config.getEventMsgProcessNum());
msgListenerContainer.setTxSize(config.getPrefetchSize());//设置有事务时处理的消息数
msgListenerContainer.setQueues(queues.values().toArray(new Queue[queues.size()]));
msgListenerContainer.start();
}
@Override
public EventTemplate getEopEventTemplate() {
return eventTemplate;
}
@Override
public EventController add(String queueName, String exchangeName,EventProcesser eventProcesser) {
return add(queueName, exchangeName, eventProcesser, defaultCodecFactory);
}
public EventController add(String queueName, String exchangeName,EventProcesser eventProcesser,CodecFactory codecFactory) {
msgAdapterHandler.add(queueName, exchangeName, eventProcesser, defaultCodecFactory);
if(isStarted.get()){
initMsgListenerAdapter();
}
return this;
}
@Override
public EventController add(Map<String, String> bindings,
EventProcesser eventProcesser) {
return add(bindings, eventProcesser,defaultCodecFactory);
}
public EventController add(Map<String, String> bindings,
EventProcesser eventProcesser, CodecFactory codecFactory) {
for(Map.Entry<String, String> item: bindings.entrySet())
msgAdapterHandler.add(item.getKey(),item.getValue(), eventProcesser,codecFactory);
return this;
}
/**
* exchange和queue是否已经绑定
*/
protected boolean beBinded(String exchangeName, String queueName) {
return binded.contains(exchangeName+"|"+queueName);
}
/**
* 声明exchange和queue已经它们的绑定关系
*/
protected synchronized void declareBinding(String exchangeName, String queueName) {
String bindRelation = exchangeName+"|"+queueName;
if (binded.contains(bindRelation)) return;
boolean needBinding = false;
DirectExchange directExchange = exchanges.get(exchangeName);
if(directExchange == null) {
directExchange = new DirectExchange(exchangeName, true, false, null);
exchanges.put(exchangeName, directExchange);
rabbitAdmin.declareExchange(directExchange);//声明exchange
needBinding = true;
}
Queue queue = queues.get(queueName);
if(queue == null) {
queue = new Queue(queueName, true, false, false);
queues.put(queueName, queue);
rabbitAdmin.declareQueue(queue); //声明queue
needBinding = true;
}
if(needBinding) {
Binding binding = BindingBuilder.bind(queue).to(directExchange).with(queueName);//将queue绑定到exchange
rabbitAdmin.declareBinding(binding);//声明绑定关系
binded.add(bindRelation);
}
}
}搞定，现在可以将DefaultEventTemplate里的注释去掉了，接下来最后完成单元测试，为了测试传递对象，建立一个PO
@SuppressWarnings("serial")
public class People implements Serializable{
private int id;
private String name;
private boolean male;
private People spouse;
private List<People> friends;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public boolean isMale() {
return male;
}
public void setMale(boolean male) {
this.male = male;
}
public People getSpouse() {
return spouse;
}
public void setSpouse(People spouse) {
this.spouse = spouse;
}
public List<People> getFriends() {
return friends;
}
public void setFriends(List<People> friends) {
this.friends = friends;
}
@Override
public String toString() {
// TODO Auto-generated method stub
return "People[id="+id+",name="+name+",male="+male+"]";
}
}建立单元测试
public class RabbitMqTest{
private String defaultHost = "127.0.0.1";
private String defaultExchange = "EXCHANGE_DIRECT_TEST";
private String defaultQueue = "QUEUE_TEST";
private DefaultEventController controller;
private EventTemplate eventTemplate;
@Before
public void init() throws IOException{
EventControlConfig config = new EventControlConfig(defaultHost);
controller = DefaultEventController.getInstance(config);
eventTemplate = controller.getEopEventTemplate();
controller.add(defaultQueue, defaultExchange, new ApiProcessEventProcessor());
controller.start();
}
@Test
public void sendString() throws SendRefuseException{
eventTemplate.send(defaultQueue, defaultExchange, "hello world");
}
@Test
public void sendObject() throws SendRefuseException{
eventTemplate.send(defaultQueue, defaultExchange, mockObj());
}
@Test
public void sendTemp() throws SendRefuseException, InterruptedException{
String tempExchange = "EXCHANGE_DIRECT_TEST_TEMP";//以前未声明的exchange
String tempQueue = "QUEUE_TEST_TEMP";//以前未声明的queue
eventTemplate.send(tempQueue, tempExchange, mockObj());
//发送成功后此时不会接受到消息，还需要绑定对应的消费程序
controller.add(tempQueue, tempExchange, new ApiProcessEventProcessor());
}
@After
public void end() throws InterruptedException{
Thread.sleep(2000);
}
private People mockObj(){
People jack = new People();
jack.setId(1);
jack.setName("JACK");
jack.setMale(true);
List<People> friends = new ArrayList<>();
friends.add(jack);
People hanMeiMei = new People();
hanMeiMei.setId(1);
hanMeiMei.setName("韩梅梅");
hanMeiMei.setMale(false);
hanMeiMei.setFriends(friends);
People liLei = new People();
liLei.setId(2);
liLei.setName("李雷");
liLei.setMale(true);
liLei.setFriends(friends);
liLei.setSpouse(hanMeiMei);
hanMeiMei.setSpouse(liLei);
return hanMeiMei;
}
class ApiProcessEventProcessor implements EventProcesser{
@Override
public void process(Object e) {//消费程序这里只是打印信息
Assert.assertNotNull(e);
System.out.println(e);
if(e instanceof People){
People people = (People)e;
System.out.println(people.getSpouse());
System.out.println(people.getFriends());
}
}
}
}看完上述内容，你们掌握怎么在Java项目中利用rabbitMQ实现一个消息收发功能的方法了吗？如果还想学到更多技能或想了解更多相关内容，欢迎关注亿速云行业资讯频道，感谢各位的阅读！
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