SpringCloud配置刷新機(jī)制的簡(jiǎn)單分析[nacos為例子]

/**
?*?@param?environment?The?current?Environment.
?*?@return?A?PropertySource,?or?null?if?there?is?none.
?*?@throws?IllegalStateException?if?there?is?a?fail-fast?condition.
?*/
PropertySource?locate(Environment?environment);

/**
?*?Nacos?Group.
?*/
private?final?String?group;

/**
?*?Nacos?dataID.
?*/
private?final?String?dataId;

/**
?*?timestamp?the?property?get.
?*/
private?final?Date?timestamp;

/**
?*?Whether?to?support?dynamic?refresh?for?this?Property?Source.
?*/
private?final?boolean?isRefreshable;

@Override
public?PropertySource?locate(Environment?env)?{
?nacosConfigProperties.setEnvironment(env);
?//?獲取nacos配置的服務(wù)類,http協(xié)議,訪問(wèn)nacos的api接口獲得配置
?ConfigService?configService?=?nacosConfigManager.getConfigService();

?if?(null?==?configService)?{
??log.warn("no?instance?of?config?service?found,?can't?load?config?from?nacos");
??return?null;
?}
?long?timeout?=?nacosConfigProperties.getTimeout();
?//?構(gòu)建一個(gè)builder
?nacosPropertySourceBuilder?=?new?NacosPropertySourceBuilder(configService,
???timeout);
?String?name?=?nacosConfigProperties.getName();

?String?dataIdPrefix?=?nacosConfigProperties.getPrefix();
?if?(StringUtils.isEmpty(dataIdPrefix))?{
??dataIdPrefix?=?name;
?}

?if?(StringUtils.isEmpty(dataIdPrefix))?{
??dataIdPrefix?=?env.getProperty("spring.application.name");
?}
????//?構(gòu)建一個(gè)復(fù)合數(shù)據(jù)源
?CompositePropertySource?composite?=?new?CompositePropertySource(
???NACOS_PROPERTY_SOURCE_NAME);
????//?加載共享的配置
?loadSharedConfiguration(composite);
?//?加載擴(kuò)展配置
?loadExtConfiguration(composite);
?//?加載應(yīng)用配置,應(yīng)用配置的優(yōu)先級(jí)是最高,所以這里放在最后面來(lái)做,是因?yàn)樘砑优渲玫牡胤蕉际莂ddFirst,所以最先的反而優(yōu)先級(jí)最后
?loadApplicationConfiguration(composite,?dataIdPrefix,?nacosConfigProperties,?env);

?return?composite;
}

executor?=?Executors.newScheduledThreadPool(1,?new?ThreadFactory()?{
????????????@Override
????????????public?Thread?newThread(Runnable?r)?{
????????????????Thread?t?=?new?Thread(r);
????????????????t.setName("com.alibaba.nacos.client.Worker."?+?agent.getName());
????????????????t.setDaemon(true);
????????????????return?t;
????????????}
????????});

executorService?=?Executors.newScheduledThreadPool(Runtime.getRuntime().availableProcessors(),?new?ThreadFactory()?{
????@Override
????public?Thread?newThread(Runnable?r)?{
????????Thread?t?=?new?Thread(r);
????????t.setName("com.alibaba.nacos.client.Worker.longPolling."?+?agent.getName());
????????t.setDaemon(true);
????????return?t;
????}
});

executor.scheduleWithFixedDelay(new?Runnable()?{
????@Override
????public?void?run()?{
????????try?{
????????????checkConfigInfo();
????????}?catch?(Throwable?e)?{
????????????LOGGER.error("["?+?agent.getName()?+?"]?[sub-check]?rotate?check?error",?e);
????????}
????}
},?1L,?10L,?TimeUnit.MILLISECONDS);

//?com.alibaba.cloud.nacos.client.NacosPropertySourceBuilder#loadNacosData
private?Map?loadNacosData(String?dataId,?String?group,
???String?fileExtension)?{
?String?data?=?null;
?try?{
??data?=?configService.getConfig(dataId,?group,?timeout);
??if?(StringUtils.isEmpty(data))?{
???log.warn(
?????"Ignore?the?empty?nacos?configuration?and?get?it?based?on?dataId[{}]?&?group[{}]",
?????dataId,?group);
???return?EMPTY_MAP;
??}
??if?(log.isDebugEnabled())?{
???log.debug(String.format(
?????"Loading?nacos?data,?dataId:?'%s',?group:?'%s',?data:?%s",?dataId,
?????group,?data));
??}
??Map?dataMap?=?NacosDataParserHandler.getInstance()
????.parseNacosData(data,?fileExtension);
??return?dataMap?==?null???EMPTY_MAP?:?dataMap;
?}
?catch?(NacosException?e)?{
??log.error("get?data?from?Nacos?error,dataId:{},?",?dataId,?e);
?}
?catch?(Exception?e)?{
??log.error("parse?data?from?Nacos?error,dataId:{},data:{},",?dataId,?data,?e);
?}
?return?EMPTY_MAP;
}

org.springframework.cloud.bootstrap.BootstrapConfiguration=\
com.alibaba.cloud.nacos.NacosConfigBootstrapConfiguration

@Bean
public?NacosConfigProperties?nacosConfigProperties(ApplicationContext?context)?{
?if?(context.getParent()?!=?null
???&&?BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
?????context.getParent(),?NacosConfigProperties.class).length?>?0)?{
??return?BeanFactoryUtils.beanOfTypeIncludingAncestors(context.getParent(),
????NacosConfigProperties.class);
?}
?return?new?NacosConfigProperties();
}

//?外層方法
public?synchronized?Set?refresh()?{
?Set?keys?=?refreshEnvironment();
?this.scope.refreshAll();
?return?keys;
}

//?
public?synchronized?Set?refreshEnvironment()?{
?Map?before?=?extract(
???this.context.getEnvironment().getPropertySources());
?addConfigFilesToEnvironment();
?Set?keys?=?changes(before,
???extract(this.context.getEnvironment().getPropertySources())).keySet();
?this.context.publishEvent(new?EnvironmentChangeEvent(this.context,?keys));
?return?keys;
}

@ManagedOperation
public?boolean?rebind(String?name)?{
?if?(!this.beans.getBeanNames().contains(name))?{
??return?false;
?}
?if?(this.applicationContext?!=?null)?{
??try?{
???Object?bean?=?this.applicationContext.getBean(name);
???//?獲取source對(duì)象
???if?(AopUtils.isAopProxy(bean))?{
????bean?=?ProxyUtils.getTargetObject(bean);
???}
???if?(bean?!=?null)?{
????//?重新觸發(fā)銷毀和初始化的周期方法
????this.applicationContext.getAutowireCapableBeanFactory()
??????.destroyBean(bean);
???????//?因?yàn)橛|發(fā)初始化生命周期，就可以觸發(fā)
???????//?org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor#postProcessBeforeInitialization
????this.applicationContext.getAutowireCapableBeanFactory()
??????.initializeBean(bean,?name);
????return?true;
???}
??}
??catch?(RuntimeException?e)?{
???this.errors.put(name,?e);
???throw?e;
??}
??catch?(Exception?e)?{
???this.errors.put(name,?e);
???throw?new?IllegalStateException("Cannot?rebind?to?"?+?name,?e);
??}
?}
?return?false;
}

@Override
public?Object?postProcessBeforeInitialization(Object?bean,?String?beanName)
??throws?BeansException?{
?if?(isRefreshScoped(beanName))?{
??return?bean;
?}
?ConfigurationProperties?annotation?=?AnnotationUtils
???.findAnnotation(bean.getClass(),?ConfigurationProperties.class);
?if?(annotation?!=?null)?{
??this.beans.put(beanName,?bean);
?}
?else?if?(this.metaData?!=?null)?{
??annotation?=?this.metaData.findFactoryAnnotation(beanName,
????ConfigurationProperties.class);
??if?(annotation?!=?null)?{
???this.beans.put(beanName,?bean);
??}
?}
?return?bean;
}

@ManagedOperation(description?=?"Dispose?of?the?current?instance?of?all?beans?"
???+?"in?this?scope?and?force?a?refresh?on?next?method?execution.")
public?void?refreshAll()?{
?super.destroy();
?this.context.publishEvent(new?RefreshScopeRefreshedEvent());
}

private?static?class?BeanLifecycleWrapper?{
????//?bean的名字
?private?final?String?name;
????//?獲取bean
?private?final?ObjectFactory?objectFactory;
????//?真正的實(shí)例
?private?Object?bean;
????//?銷毀函數(shù)
?private?Runnable?callback;
}?

@Override
public?Object?get(String?name,?ObjectFactory?objectFactory)?{
?BeanLifecycleWrapper?value?=?this.cache.put(name,
???new?BeanLifecycleWrapper(name,?objectFactory));
?this.locks.putIfAbsent(name,?new?ReentrantReadWriteLock());
?try?{
??return?value.getBean();
?}
?catch?(RuntimeException?e)?{
??this.errors.put(name,?e);
??throw?e;
?}
}

String?scopeName?=?mbd.getScope();
final?Scope?scope?=?this.scopes.get(scopeName);
if?(scope?==?null)?{
?throw?new?IllegalStateException("No?Scope?registered?for?scope?name?'"?+?scopeName?+?"'");
}
try?{
?Object?scopedInstance?=?scope.get(beanName,?()?->?{
??beforePrototypeCreation(beanName);
??try?{
???return?createBean(beanName,?mbd,?args);
??}
??finally?{
???afterPrototypeCreation(beanName);
??}
?});
?bean?=?getObjectForBeanInstance(scopedInstance,?name,?beanName,?mbd);
}

public?Object?getBean()?{
?if?(this.bean?==?null)?{
??synchronized?(this.name)?{
???if?(this.bean?==?null)?{
???????//?因?yàn)閎ean為空，所以會(huì)觸發(fā)一次bean的重新初始化，走了一遍生命周期流程所以配置又回來(lái)了
????this.bean?=?this.objectFactory.getObject();
???}
??}
?}
?return?this.bean;
}