使用spring boot + rabbitmq的時候,在開發過程中,可能會想要臨時停用/啟用監聽,或修改監聽消費者數量。如果每次修改都重新開機比較浪費時間,是以研究了一下不停機就啟用停用監聽或修改一些配置
一. 關于rabbitmq監聽的配置
- 配置屬性類:RabbitProperties,包含rabbitmq的認證、監聽、發送者以及其他的一些配置
- 自動配置類:RabbitAutoConfiguration,主要配置rabbitmq的連接配接工廠和發送者等,不包含監聽的配置
- rabbitmq監聽的配置是RabbitAnnotationDrivenConfiguration,是通過RabbitAutoConfiguration引入的
@Configuration
@ConditionalOnClass({ RabbitTemplate.class, Channel.class })
@EnableConfigurationProperties(RabbitProperties.class)
@Import(RabbitAnnotationDrivenConfiguration.class)
public class RabbitAutoConfiguration {
...
}
- RabbitAnnotationDrivenConfiguration中主要就是監聽工廠的配置、監聽工廠,但是這裡也隻是建立bean,并沒有真正的初始化
- 通過配置裡的bean類名,分析一下,rabbitmq的監聽肯定是由監聽工廠建立的,是以找到監聽工廠SimpleRabbitListenerContainerFactory
@Bean
@ConditionalOnMissingBean(name = "rabbitListenerContainerFactory")
public SimpleRabbitListenerContainerFactory rabbitListenerContainerFactory(
SimpleRabbitListenerContainerFactoryConfigurer configurer,
ConnectionFactory connectionFactory) {
SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
configurer.configure(factory, connectionFactory);
return factory;
}
- 既然自動配置裡面沒有初始化監聽,那就應該是在其他地方調用的,進入監聽工廠類中,發現有initializeContainer(SimpleMessageListenerContainer instance)方法,猜測初始化肯定與這個方法有關,是以檢視有哪些地方調用,于是找到RabbitListenerEndpointRegistry.createListenerContainer(RabbitListenerEndpoint endpoint,RabbitListenerContainerFactory<?> factory)方法中有建立監聽容器和初始化的代碼
/**
* Create and start a new {@link MessageListenerContainer} using the specified factory.
* @param endpoint the endpoint to create a {@link MessageListenerContainer}.
* @param factory the {@link RabbitListenerContainerFactory} to use.
* @return the {@link MessageListenerContainer}.
*/
protected MessageListenerContainer createListenerContainer(RabbitListenerEndpoint endpoint,
RabbitListenerContainerFactory<?> factory) {
MessageListenerContainer listenerContainer = factory.createListenerContainer(endpoint);
if (listenerContainer instanceof InitializingBean) {
try {
((InitializingBean) listenerContainer).afterPropertiesSet();
}
catch (Exception ex) {
throw new BeanInitializationException("Failed to initialize message listener container", ex);
}
}
int containerPhase = listenerContainer.getPhase();
if (containerPhase < Integer.MAX_VALUE) { // a custom phase value
if (this.phase < Integer.MAX_VALUE && this.phase != containerPhase) {
throw new IllegalStateException("Encountered phase mismatch between container factory definitions: " +
this.phase + " vs " + containerPhase);
}
this.phase = listenerContainer.getPhase();
}
return listenerContainer;
}
- 繼續找調用這個方法的地方,找到RabbitListenerEndpointRegistrar.afterPropertiesSet()方法之後,發現調用的地方很多了
- 看看afterPropertiesSet方法,是InitializingBean接口中的,猜測應該是spring容器建立bean之後都會調用的bean初始化的方法,是以查找找到RabbitListenerEndpointRegistrar是在哪裡建立的執行個體。原來是在RabbitListenerAnnotationBeanPostProcessor中的私有屬性,而RabbitListenerAnnotationBeanPostProcessor是在RabbitBootstrapConfiguration這個自動配置裡面初始化的,是以這就找到rabbitmq初始化監聽的源頭了
二. 動态管理rabbitmq監聽
- 回到最初的問題,想要動态的啟用停用mq的監聽,是以先看看初始化配置的類,既然有初始化,那可能會有相關的管理,于是在RabbitListenerEndpointRegistry中找到了start()和stop()方法,裡面有對監聽容器進行操作,主要源碼如下
/**
* @return the managed {@link MessageListenerContainer} instance(s).
*/
public Collection<MessageListenerContainer> getListenerContainers() {
return Collections.unmodifiableCollection(this.listenerContainers.values());
}
@Override
public void start() {
for (MessageListenerContainer listenerContainer : getListenerContainers()) {
startIfNecessary(listenerContainer);
}
}
/**
* Start the specified {@link MessageListenerContainer} if it should be started
* on startup or when start is called explicitly after startup.
* @see MessageListenerContainer#isAutoStartup()
*/
private void startIfNecessary(MessageListenerContainer listenerContainer) {
if (this.contextRefreshed || listenerContainer.isAutoStartup()) {
listenerContainer.start();
}
}
@Override
public void stop() {
for (MessageListenerContainer listenerContainer : getListenerContainers()) {
listenerContainer.stop();
}
}
- 寫個controller,注入RabbitListenerEndpointRegistry,使用start()和stop()對監聽進行啟用停用的操作,并且RabbitListenerEndpointRegistry執行個體還可以擷取監聽容器,對監聽的一些參數也能進行修改,比如消費者數量。代碼如下:
import java.util.Set;
import javax.annotation.Resource;
import org.springframework.amqp.rabbit.listener.RabbitListenerEndpointRegistry;
import org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.itopener.framework.ResultMap;
/**
* Created by fuwei.deng on 2017年7月24日.
*/
@RestController
@RequestMapping("rabbitmq/listener")
public class RabbitMQController {
@Resource
private RabbitListenerEndpointRegistry rabbitListenerEndpointRegistry;
@RequestMapping("stop")
public ResultMap stop(){
rabbitListenerEndpointRegistry.stop();
return ResultMap.buildSuccess();
}
@RequestMapping("start")
public ResultMap start(){
rabbitListenerEndpointRegistry.start();
return ResultMap.buildSuccess();
}
@RequestMapping("setup")
public ResultMap setup(int consumer, int maxConsumer){
Set<String> containerIds = rabbitListenerEndpointRegistry.getListenerContainerIds();
SimpleMessageListenerContainer container = null;
for(String id : containerIds){
container = (SimpleMessageListenerContainer) rabbitListenerEndpointRegistry.getListenerContainer(id);
if(container != null){
container.setConcurrentConsumers(consumer);
container.setMaxConcurrentConsumers(maxConsumer);
}
}
return ResultMap.buildSuccess();
}
}
轉載于:https://my.oschina.net/dengfuwei/blog/1595044