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今天小编给大家分享一下SpringCloud @RefreshScope刷新机制是什么的相关知识点，内容详细，逻辑清晰，相信大部分人都还太了解这方面的知识，所以分享这篇文章给大家参考一下，希望大家阅读完这篇文章后有所收获，下面我们一起来了解一下吧。
在学习 nacos 的配置修改发现用到了 @RefreshScope 注解，将 spring boot 的日志调整如下
logging:
level:
com:
alibaba:
cloud: debug
org:
springframework:
context: debug
cloud: debug
调用 nacos 的配置修改，看到如下信息
2023-03-10 15:48:15.332 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.ClientWorker Caller+0 at com.alibaba.nacos.client.config.impl.ClientWorker.parseUpdateDataIdResponse(ClientWorker.java:486)
- [fixed-node1.hahaou.cn_8848] [polling-resp] config changed. dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP
2023-03-10 15:48:15.333 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.ClientWorker Caller+0 at com.alibaba.nacos.client.config.impl.ClientWorker$LongPollingRunnable.run(ClientWorker.java:598)
- get changedGroupKeys:[soft-jraft-apache-derby-config-test.yaml+DEFAULT_GROUP]
2023-03-10 15:48:15.400 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.ClientWorker Caller+0 at com.alibaba.nacos.client.config.impl.ClientWorker$LongPollingRunnable.run(ClientWorker.java:616)
- [fixed-node1.hahaou.cn_8848] [data-received] dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP, tenant=null, md5=5f214678315ac83144e77f4c4b3b3416, content=spring:
youxia:
config:
name: test, type=
2023-03-10 15:48:15.400 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.CacheData Caller+0 at com.alibaba.nacos.client.config.impl.CacheData$1.run(CacheData.java:199)
- [fixed-node1.hahaou.cn_8848] [notify-context] dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP, md5=5f214678315ac83144e77f4c4b3b3416
2023-03-10 15:48:15.401 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.cloud.endpoint.event.RefreshEventListener Caller+0 at org.springframework.cloud.endpoint.event.RefreshEventListener.handle(RefreshEventListener.java:71)
- Event received Refresh Nacos config
2023-03-10 15:48:17.002 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.a.AnnotationConfigApplicationContext Caller+0 at org.springframework.context.support.AbstractApplicationContext.prepareRefresh(AbstractApplicationContext.java:596)
- Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@653cd99a
2023-03-10 15:48:18.632 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] c.a.cloud.nacos.client.NacosPropertySourceBuilder Caller+0 at com.alibaba.cloud.nacos.client.NacosPropertySourceBuilder.loadNacosData(NacosPropertySourceBuilder.java:93)
- Loading nacos data, dataId: 'soft-jraft-apache-derby-config-test.yaml', group: 'DEFAULT_GROUP', data: spring:
youxia:
config:
name: test
2023-03-10 15:48:18.706 WARN [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] c.a.cloud.nacos.client.NacosPropertySourceBuilder Caller+0 at com.alibaba.cloud.nacos.client.NacosPropertySourceBuilder.loadNacosData(NacosPropertySourceBuilder.java:87)
- Ignore the empty nacos configuration and get it based on dataId[soft-jraft-apache-derby-config] & group[DEFAULT_GROUP]
2023-03-10 15:48:18.789 WARN [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] c.a.cloud.nacos.client.NacosPropertySourceBuilder Caller+0 at com.alibaba.cloud.nacos.client.NacosPropertySourceBuilder.loadNacosData(NacosPropertySourceBuilder.java:87)
- Ignore the empty nacos configuration and get it based on dataId[soft-jraft-apache-derby-config.properties] & group[DEFAULT_GROUP]
2023-03-10 15:48:18.790 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.b.c.PropertySourceBootstrapConfiguration Caller+0 at org.springframework.cloud.bootstrap.config.PropertySourceBootstrapConfiguration.initialize(PropertySourceBootstrapConfiguration.java:112)
- Located property source: [BootstrapPropertySource@1783236684 {name='bootstrapProperties-soft-jraft-apache-derby-config.properties,DEFAULT_GROUP', properties={}}, BootstrapPropertySource@942001677 {name='bootstrapProperties-soft-jraft-apache-derby-config,DEFAULT_GROUP', properties={}}, BootstrapPropertySource@1637255792 {name='bootstrapProperties-soft-jraft-apache-derby-config-test.yaml,DEFAULT_GROUP', properties={spring.youxia.config.name=test}}]
2023-03-10 15:48:18.800 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] org.springframework.boot.SpringApplication Caller+0 at org.springframework.boot.SpringApplication.logStartupProfileInfo(SpringApplication.java:651)
- No active profile set, falling back to default profiles: default
2023-03-10 15:48:18.801 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.a.AnnotationConfigApplicationContext Caller+0 at org.springframework.context.support.AbstractApplicationContext.prepareRefresh(AbstractApplicationContext.java:596)
- Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@6709b8b
2023-03-10 15:48:18.806 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] org.springframework.boot.SpringApplication Caller+0 at org.springframework.boot.StartupInfoLogger.logStarted(StartupInfoLogger.java:61)
- Started application in 3.403 seconds (JVM running for 54.758)
2023-03-10 15:48:18.807 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.a.AnnotationConfigApplicationContext Caller+0 at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:1006)
- Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@6709b8b, started on Fri Mar 10 15:48:18 CST 2023, parent: org.springframework.context.annotation.AnnotationConfigApplicationContext@653cd99a
2023-03-10 15:48:18.808 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.a.AnnotationConfigApplicationContext Caller+0 at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:1006)
- Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@653cd99a, started on Fri Mar 10 15:48:17 CST 2023
2023-03-10 15:48:18.819 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.cloud.endpoint.event.RefreshEventListener Caller+0 at org.springframework.cloud.endpoint.event.RefreshEventListener.handle(RefreshEventListener.java:73)
- Refresh keys changed: [spring.youxia.config.name]
2023-03-10 15:48:18.820 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] c.a.cloud.nacos.refresh.NacosContextRefresher Caller+0 at com.alibaba.cloud.nacos.refresh.NacosContextRefresher$1.innerReceive(NacosContextRefresher.java:136)
- Refresh Nacos config group=DEFAULT_GROUP,dataId=soft-jraft-apache-derby-config-test.yaml,configInfo=spring:
youxia:
config:
name: test
2023-03-10 15:48:18.820 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.CacheData Caller+0 at com.alibaba.nacos.client.config.impl.CacheData$1.run(CacheData.java:222)
- [fixed-node1.hahaou.cn_8848] [notify-ok] dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP, md5=5f214678315ac83144e77f4c4b3b3416, listener=com.alibaba.cloud.nacos.refresh.NacosContextRefresher$1@59af462e
2023-03-10 15:48:18.820 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.CacheData Caller+0 at com.alibaba.nacos.client.config.impl.CacheData.safeNotifyListener(CacheData.java:248)
- [fixed-node1.hahaou.cn_8848] [notify-listener] time cost=3420ms in ClientWorker, dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP, md5=5f214678315ac83144e77f4c4b3b3416, listener=com.alibaba.cloud.nacos.refresh.NacosContextRefresher$1@59af462e
使用Spring Cloud Alibaba接入Nacos配置中心，获取配置信息name为：test
使用Spring Cloud Alibaba接入Nacos配置中心，获取配置信息value为：null
得知保存配置后进行了 jvm 重启。
package org.springframework.cloud.context.config.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.context.annotation.Scope;
import org.springframework.context.annotation.ScopedProxyMode;
/**
* Convenience annotation to put a <code>@Bean</code> definition in
* {@link org.springframework.cloud.context.scope.refresh.RefreshScope refresh scope}.
* Beans annotated this way can be refreshed at runtime and any components that are using
* them will get a new instance on the next method call, fully initialized and injected
* with all dependencies.
*
* @author Dave Syer
*
*/
@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Scope("refresh")
@Documented
public @interface RefreshScope {
/**
* @see Scope#proxyMode()
* @return proxy mode
*/
ScopedProxyMode proxyMode() default ScopedProxyMode.TARGET_CLASS;
}可以得知，@RefreshScope 是一个 scopeName 为 refresh 的 @Scope。
package org.springframework.context.annotation;
/**
* Enumerates the various scoped-proxy options.
*
* <p>For a more complete discussion of exactly what a scoped proxy is, see the
* section of the Spring reference documentation entitled '<em>Scoped beans as
* dependencies</em>'.
*
* @author Mark Fisher
* @since 2.5
* @see ScopeMetadata
*/
public enum ScopedProxyMode {
/**
* Default typically equals {@link #NO}, unless a different default
* has been configured at the component-scan instruction level.
*/
DEFAULT,
/**
* Do not create a scoped proxy.
* <p>This proxy-mode is not typically useful when used with a
* non-singleton scoped instance, which should favor the use of the
* {@link #INTERFACES} or {@link #TARGET_CLASS} proxy-modes instead if it
* is to be used as a dependency.
*/
NO,
/**
* Create a JDK dynamic proxy implementing <i>all</i> interfaces exposed by
* the class of the target object.
*/
INTERFACES,
/**
* Create a class-based proxy (uses CGLIB).
*/
TARGET_CLASS
}由枚举 ScopedProxyMode 得知，ScopedProxyMode.TARGET_CLASS 通过 cglib 生成一个代理类进行字节码增强
部分源码如下
package org.springframework.cloud.autoconfigure;
import java.util.HashSet;
import java.util.Set;
import javax.annotation.PostConstruct;
import org.springframework.aop.scope.ScopedProxyUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanDefinitionHolder;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.boot.autoconfigure.AutoConfigureBefore;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.boot.context.properties.bind.Bindable;
import org.springframework.boot.context.properties.bind.Binder;
import org.springframework.cloud.context.refresh.ContextRefresher;
import org.springframework.cloud.context.scope.refresh.RefreshScope;
import org.springframework.cloud.endpoint.event.RefreshEventListener;
import org.springframework.cloud.logging.LoggingRebinder;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.weaving.LoadTimeWeaverAware;
import org.springframework.core.env.Environment;
import org.springframework.core.env.StandardEnvironment;
import org.springframework.instrument.classloading.LoadTimeWeaver;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
/**
* Autoconfiguration for the refresh scope and associated features to do with changes in
* the Environment (e.g. rebinding logger levels).
*
* @author Dave Syer
* @author Venil Noronha
*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(RefreshScope.class)
@ConditionalOnProperty(name = RefreshAutoConfiguration.REFRESH_SCOPE_ENABLED,
matchIfMissing = true)
@AutoConfigureBefore(HibernateJpaAutoConfiguration.class)
public class RefreshAutoConfiguration {
/**
* Name of the refresh scope name.
*/
public static final String REFRESH_SCOPE_NAME = "refresh";
/**
* Name of the prefix for refresh scope.
*/
public static final String REFRESH_SCOPE_PREFIX = "spring.cloud.refresh";
/**
* Name of the enabled prefix for refresh scope.
*/
public static final String REFRESH_SCOPE_ENABLED = REFRESH_SCOPE_PREFIX + ".enabled";
@Bean
@ConditionalOnMissingBean(RefreshScope.class)
public static RefreshScope refreshScope() {
return new RefreshScope();
}
@Bean
@ConditionalOnMissingBean
public static LoggingRebinder loggingRebinder() {
return new LoggingRebinder();
}
@Bean
@ConditionalOnMissingBean
public ContextRefresher contextRefresher(ConfigurableApplicationContext context,
RefreshScope scope) {
return new ContextRefresher(context, scope);
}
@Bean
public RefreshEventListener refreshEventListener(ContextRefresher contextRefresher) {
return new RefreshEventListener(contextRefresher);
}
}@ConditionalOnProperty(name = RefreshAutoConfiguration.REFRESH_SCOPE_ENABLED, matchIfMissing = true)
通过上面的注解得知，自动刷新在 spring cloud 中默认启用
nacos中添加配置
public NacosConfigService(Properties properties) throws NacosException {
ValidatorUtils.checkInitParam(properties);
String encodeTmp = properties.getProperty(PropertyKeyConst.ENCODE);
if (StringUtils.isBlank(encodeTmp)) {
this.encode = Constants.ENCODE;
} else {
this.encode = encodeTmp.trim();
}
initNamespace(properties);
this.agent = new MetricsHttpAgent(new ServerHttpAgent(properties));
this.agent.start();
this.worker = new ClientWorker(this.agent, this.configFilterChainManager, properties);
}NacosConfigService 构造器创建 ClientWorker 对象
public ClientWorker(final HttpAgent agent, final ConfigFilterChainManager configFilterChainManager,
final Properties properties) {
this.agent = agent;
this.configFilterChainManager = configFilterChainManager;
// Initialize the timeout parameter
init(properties);
this.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;
}
});
this.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;
}
});
this.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);
}
public void checkConfigInfo() {
// Dispatch taskes.
int listenerSize = cacheMap.size();
// Round up the longingTaskCount.
int longingTaskCount = (int) Math.ceil(listenerSize / ParamUtil.getPerTaskConfigSize());
if (longingTaskCount > currentLongingTaskCount) {
for (int i = (int) currentLongingTaskCount; i < longingTaskCount; i++) {
// The task list is no order.So it maybe has issues when changing.
executorService.execute(new LongPollingRunnable(i));
}
currentLongingTaskCount = longingTaskCount;
}
}
class LongPollingRunnable implements Runnable {
private final int taskId;
public LongPollingRunnable(int taskId) {
this.taskId = taskId;
}
@Override
public void run() {
List<CacheData> cacheDatas = new ArrayList<CacheData>();
List<String> inInitializingCacheList = new ArrayList<String>();
try {
// check failover config
for (CacheData cacheData : cacheMap.values()) {
if (cacheData.getTaskId() == taskId) {
cacheDatas.add(cacheData);
try {
checkLocalConfig(cacheData);
if (cacheData.isUseLocalConfigInfo()) {
cacheData.checkListenerMd5();
}
} catch (Exception e) {
LOGGER.error("get local config info error", e);
}
}
}
// check server config
List<String> changedGroupKeys = checkUpdateDataIds(cacheDatas, inInitializingCacheList);
if (!CollectionUtils.isEmpty(changedGroupKeys)) {
LOGGER.info("get changedGroupKeys:" + changedGroupKeys);
}
for (String groupKey : changedGroupKeys) {
String[] key = GroupKey.parseKey(groupKey);
String dataId = key[0];
String group = key[1];
String tenant = null;
if (key.length == 3) {
tenant = key[2];
}
try {
String[] ct = getServerConfig(dataId, group, tenant, 3000L);
CacheData cache = cacheMap.get(GroupKey.getKeyTenant(dataId, group, tenant));
cache.setContent(ct[0]);
if (null != ct[1]) {
cache.setType(ct[1]);
}
LOGGER.info("[{}] [data-received] dataId={}, group={}, tenant={}, md5={}, content={}, type={}",
agent.getName(), dataId, group, tenant, cache.getMd5(),
ContentUtils.truncateContent(ct[0]), ct[1]);
} catch (NacosException ioe) {
String message = String
.format("[%s] [get-update] get changed config exception. dataId=%s, group=%s, tenant=%s",
agent.getName(), dataId, group, tenant);
LOGGER.error(message, ioe);
}
}
for (CacheData cacheData : cacheDatas) {
if (!cacheData.isInitializing() || inInitializingCacheList
.contains(GroupKey.getKeyTenant(cacheData.dataId, cacheData.group, cacheData.tenant))) {
cacheData.checkListenerMd5();
cacheData.setInitializing(false);
}
}
inInitializingCacheList.clear();
executorService.execute(this);
} catch (Throwable e) {
// If the rotation training task is abnormal, the next execution time of the task will be punished
LOGGER.error("longPolling error : ", e);
executorService.schedule(this, taskPenaltyTime, TimeUnit.MILLISECONDS);
}
}
}ClientWorker checkConfigInfo() 中通过线程池创建 LongPollingRunnable 对象，线程池名称前缀为 com.alibaba.nacos.client.Worker.longPolling
void checkListenerMd5() {
for (ManagerListenerWrap wrap : listeners) {
if (!md5.equals(wrap.lastCallMd5)) {
safeNotifyListener(dataId, group, content, type, md5, wrap);
}
}
}
private void safeNotifyListener(final String dataId, final String group, final String content, final String type,
final String md5, final ManagerListenerWrap listenerWrap) {
final Listener listener = listenerWrap.listener;
Runnable job = new Runnable() {
@Override
public void run() {
ClassLoader myClassLoader = Thread.currentThread().getContextClassLoader();
ClassLoader appClassLoader = listener.getClass().getClassLoader();
try {
if (listener instanceof AbstractSharedListener) {
AbstractSharedListener adapter = (AbstractSharedListener) listener;
adapter.fillContext(dataId, group);
LOGGER.info("[{}] [notify-context] dataId={}, group={}, md5={}", name, dataId, group, md5);
}
// 执行回调之前先将线程classloader设置为具体webapp的classloader，以免回调方法中调用spi接口是出现异常或错用（多应用部署才会有该问题）。
Thread.currentThread().setContextClassLoader(appClassLoader);
ConfigResponse cr = new ConfigResponse();
cr.setDataId(dataId);
cr.setGroup(group);
cr.setContent(content);
configFilterChainManager.doFilter(null, cr);
String contentTmp = cr.getContent();
listener.receiveConfigInfo(contentTmp);
// compare lastContent and content
if (listener instanceof AbstractConfigChangeListener) {
Map data = ConfigChangeHandler.getInstance()
.parseChangeData(listenerWrap.lastContent, content, type);
ConfigChangeEvent event = new ConfigChangeEvent(data);
((AbstractConfigChangeListener) listener).receiveConfigChange(event);
listenerWrap.lastContent = content;
}
listenerWrap.lastCallMd5 = md5;
LOGGER.info("[{}] [notify-ok] dataId={}, group={}, md5={}, listener={} ", name, dataId, group, md5,
listener);
} catch (NacosException ex) {
LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} errCode={} errMsg={}",
name, dataId, group, md5, listener, ex.getErrCode(), ex.getErrMsg());
} catch (Throwable t) {
LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} tx={}", name, dataId,
group, md5, listener, t.getCause());
} finally {
Thread.currentThread().setContextClassLoader(myClassLoader);
}
}
};
final long startNotify = System.currentTimeMillis();
try {
if (null != listener.getExecutor()) {
listener.getExecutor().execute(job);
} else {
job.run();
}
} catch (Throwable t) {
LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} throwable={}", name, dataId,
group, md5, listener, t.getCause());
}
final long finishNotify = System.currentTimeMillis();
LOGGER.info("[{}] [notify-listener] time cost={}ms in ClientWorker, dataId={}, group={}, md5={}, listener={} ",
name, (finishNotify - startNotify), dataId, group, md5, listener);
}调用 CacheData 的 checkListenerMd5()
public abstract class AbstractSharedListener implements Listener {
private volatile String dataId;
private volatile String group;
public final void fillContext(String dataId, String group) {
this.dataId = dataId;
this.group = group;
}
@Override
public final void receiveConfigInfo(String configInfo) {
innerReceive(dataId, group, configInfo);
}
@Override
public Executor getExecutor() {
return null;
}
/**
* receive.
*
* @param dataId data ID
* @param group group
* @param configInfo content
*/
public abstract void innerReceive(String dataId, String group, String configInfo);
}调用 AbstractSharedListener 的 receiveConfigInfo()，在 NacosContextRefresher 的 registerNacosListener() 中进行实现
private void registerNacosListener(final String groupKey, final String dataKey) {
String key = NacosPropertySourceRepository.getMapKey(dataKey, groupKey);
Listener listener = listenerMap.computeIfAbsent(key,
lst -> new AbstractSharedListener() {
@Override
public void innerReceive(String dataId, String group,
String configInfo) {
refreshCountIncrement();
nacosRefreshHistory.addRefreshRecord(dataId, group, configInfo);
// todo feature: support single refresh for listening
applicationContext.publishEvent(
new RefreshEvent(this, null, "Refresh Nacos config"));
if (log.isDebugEnabled()) {
log.debug(String.format(
"Refresh Nacos config group=%s,dataId=%s,configInfo=%s",
group, dataId, configInfo));
}
}
});
try {
configService.addListener(dataKey, groupKey, listener);
}
catch (NacosException e) {
log.warn(String.format(
"register fail for nacos listener ,dataId=[%s],group=[%s]", dataKey,
groupKey), e);
}
}最终通过 ApplicationContext 发布事件 RefreshEvent
至此，nacos 逻辑执行完毕。
public class RefreshEventListener implements SmartApplicationListener {
private static Log log = LogFactory.getLog(RefreshEventListener.class);
private ContextRefresher refresh;
private AtomicBoolean ready = new AtomicBoolean(false);
public RefreshEventListener(ContextRefresher refresh) {
this.refresh = refresh;
}
@Override
public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
return ApplicationReadyEvent.class.isAssignableFrom(eventType)
|| RefreshEvent.class.isAssignableFrom(eventType);
}
@Override
public void onApplicationEvent(ApplicationEvent event) {
if (event instanceof ApplicationReadyEvent) {
handle((ApplicationReadyEvent) event);
}
else if (event instanceof RefreshEvent) {
handle((RefreshEvent) event);
}
}
public void handle(ApplicationReadyEvent event) {
this.ready.compareAndSet(false, true);
}
public void handle(RefreshEvent event) {
if (this.ready.get()) { // don't handle events before app is ready
log.debug("Event received " + event.getEventDesc());
Set<String> keys = this.refresh.refresh();
log.info("Refresh keys changed: " + keys);
}
}
}调用 RefreshEventListener 的 onApplicationEvent()，事件对象为 RefreshEvent。
执行完可以看到打印了日志
Event received Refresh Nacos config
后面调用 ContextRefresher 的 refresh()
public synchronized Set<String> refresh() {
Set<String> keys = refreshEnvironment();
this.scope.refreshAll();
return keys;
}
public synchronized Set<String> refreshEnvironment() {
Map<String, Object> before = extract(
this.context.getEnvironment().getPropertySources());
addConfigFilesToEnvironment();
Set<String> keys = changes(before,
extract(this.context.getEnvironment().getPropertySources())).keySet();
this.context.publishEvent(new EnvironmentChangeEvent(this.context, keys));
return keys;
}
/* For testing. */ ConfigurableApplicationContext addConfigFilesToEnvironment() {
ConfigurableApplicationContext capture = null;
try {
StandardEnvironment environment = copyEnvironment(
this.context.getEnvironment());
SpringApplicationBuilder builder = new SpringApplicationBuilder(Empty.class)
.bannerMode(Mode.OFF).web(WebApplicationType.NONE)
.environment(environment);
// Just the listeners that affect the environment (e.g. excluding logging
// listener because it has side effects)
builder.application()
.setListeners(Arrays.asList(new BootstrapApplicationListener(),
new ConfigFileApplicationListener()));
capture = builder.run();
if (environment.getPropertySources().contains(REFRESH_ARGS_PROPERTY_SOURCE)) {
environment.getPropertySources().remove(REFRESH_ARGS_PROPERTY_SOURCE);
}
MutablePropertySources target = this.context.getEnvironment()
.getPropertySources();
String targetName = null;
for (PropertySource<?> source : environment.getPropertySources()) {
String name = source.getName();
if (target.contains(name)) {
targetName = name;
}
if (!this.standardSources.contains(name)) {
if (target.contains(name)) {
target.replace(name, source);
}
else {
if (targetName != null) {
target.addAfter(targetName, source);
// update targetName to preserve ordering
targetName = name;
}
else {
// targetName was null so we are at the start of the list
target.addFirst(source);
targetName = name;
}
}
}
}
}
finally {
ConfigurableApplicationContext closeable = capture;
while (closeable != null) {
try {
closeable.close();
}
catch (Exception e) {
// Ignore;
}
if (closeable.getParent() instanceof ConfigurableApplicationContext) {
closeable = (ConfigurableApplicationContext) closeable.getParent();
}
else {
break;
}
}
}
return capture;
}refreshEnvironment() 中执行如下操作
addConfigFilesToEnvironment() 添加到配置文件到环境中，发布一系列事件 BootstrapApplicationListener、ConfigFileApplicationListener
调用 EventPublishingRunListener 的发布一系列事件进行 jvm 的重启相关操作，其中 EventPublishingRunListener 是默认的监听器，在 spring boot 的 META-INF/spring.factories 中进行了指定
# Run Listeners
org.springframework.boot.SpringApplicationRunListener=\
org.springframework.boot.context.event.EventPublishingRunListener
public class EventPublishingRunListener implements SpringApplicationRunListener, Ordered {
private final SpringApplication application;
private final String[] args;
private final SimpleApplicationEventMulticaster initialMulticaster;
public EventPublishingRunListener(SpringApplication application, String[] args) {
this.application = application;
this.args = args;
this.initialMulticaster = new SimpleApplicationEventMulticaster();
for (ApplicationListener<?> listener : application.getListeners()) {
this.initialMulticaster.addApplicationListener(listener);
}
}
@Override
public int getOrder() {
return 0;
}
@Override
public void starting() {
this.initialMulticaster.multicastEvent(new ApplicationStartingEvent(this.application, this.args));
}
@Override
public void environmentPrepared(ConfigurableEnvironment environment) {
this.initialMulticaster
.multicastEvent(new ApplicationEnvironmentPreparedEvent(this.application, this.args, environment));
}
@Override
public void contextPrepared(ConfigurableApplicationContext context) {
this.initialMulticaster
.multicastEvent(new ApplicationContextInitializedEvent(this.application, this.args, context));
}
@Override
public void contextLoaded(ConfigurableApplicationContext context) {
for (ApplicationListener<?> listener : this.application.getListeners()) {
if (listener instanceof ApplicationContextAware) {
((ApplicationContextAware) listener).setApplicationContext(context);
}
context.addApplicationListener(listener);
}
this.initialMulticaster.multicastEvent(new ApplicationPreparedEvent(this.application, this.args, context));
}
@Override
public void started(ConfigurableApplicationContext context) {
context.publishEvent(new ApplicationStartedEvent(this.application, this.args, context));
}
@Override
public void running(ConfigurableApplicationContext context) {
context.publishEvent(new ApplicationReadyEvent(this.application, this.args, context));
}
@Override
public void failed(ConfigurableApplicationContext context, Throwable exception) {
ApplicationFailedEvent event = new ApplicationFailedEvent(this.application, this.args, context, exception);
if (context != null && context.isActive()) {
// Listeners have been registered to the application context so we should
// use it at this point if we can
context.publishEvent(event);
}
else {
// An inactive context may not have a multicaster so we use our multicaster to
// call all of the context's listeners instead
if (context instanceof AbstractApplicationContext) {
for (ApplicationListener<?> listener : ((AbstractApplicationContext) context)
.getApplicationListeners()) {
this.initialMulticaster.addApplicationListener(listener);
}
}
this.initialMulticaster.setErrorHandler(new LoggingErrorHandler());
this.initialMulticaster.multicastEvent(event);
}
}
private static class LoggingErrorHandler implements ErrorHandler {
private static final Log logger = LogFactory.getLog(EventPublishingRunListener.class);
@Override
public void handleError(Throwable throwable) {
logger.warn("Error calling ApplicationEventListener", throwable);
}
}
}调用了 contextLoaded()，在 RestartListener 的 onApplicationEvent() 中进行调用
public class RestartListener implements SmartApplicationListener {
private ConfigurableApplicationContext context;
private ApplicationPreparedEvent event;
@Override
public int getOrder() {
return 0;
}
@Override
public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
return ApplicationPreparedEvent.class.isAssignableFrom(eventType)
|| ContextRefreshedEvent.class.isAssignableFrom(eventType)
|| ContextClosedEvent.class.isAssignableFrom(eventType);
}
@Override
public boolean supportsSourceType(Class<?> sourceType) {
return true;
}
@Override
public void onApplicationEvent(ApplicationEvent input) {
if (input instanceof ApplicationPreparedEvent) {
this.event = (ApplicationPreparedEvent) input;
if (this.context == null) {
this.context = this.event.getApplicationContext();
}
}
else if (input instanceof ContextRefreshedEvent) {
if (this.context != null && input.getSource().equals(this.context)
&& this.event != null) {
this.context.publishEvent(this.event);
}
}
else {
if (this.context != null && input.getSource().equals(this.context)) {
this.context = null;
this.event = null;
}
}
}
}RestartListener 的 onApplicationEvent() 传入 ApplicationPreparedEvent，调用 AbstractApplicationContext 的 refresh()，即进行 ioc 容器重启，此时是第一次
调用 EventPublishingRunListener 的 running()，进行新的配置加载
调用 PropertySourceBootstrapConfiguration 的 initialize()，间接调用 NacosPropertySourceLocator 的 locate() 进行文件加载
调用 RestartListener 的 onApplicationEvent()，参数为 ApplicationPreparedEvent，调用 AbstractApplicationContext 的 refresh() 进行 ioc 容器重启，此时是第二次
调用 RestartListener 的 onApplicationEvent()，参数为 ContextRefreshedEvent
至此，ContextRefresher 的 refreshEnvironment() 逻辑执行完毕
接下来调用 RefreshScope 的 refreshAll()，间接调用父类 GenericScope 的 destroy()，发布事件 RefreshScopeRefreshedEvent 到 ApplicationContext 中
通过 NacosWatch 开启 ThreadPoolTaskScheduler 进行定时任务发起，事件为 HeartbeatEvent。
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