springclout Config刷新配置源码解析

简介

在使用springckoud config的时候，修改了配置，是需要调用/actuator/refresh来刷新客户端的配置

以下源码为了控制篇幅会有删减

/actuator/refresh

@Endpoint(id = "refresh")
public class RefreshEndpoint {
  ...
 @WriteOperation
 public Collection<String> refresh() {
  Set<String> keys = this.contextRefresher.refresh();
  return keys;
 }
}
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当我们调用/actuator/refresh的时候会调用到org.springframework.cloud.endpoint.RefreshEndpoint#refresh

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;
	}
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可以看到refresh 方法中加上了synchronized，解决并发问题
调用refreshEnvironment方法后对

refreshEnvironment方法中
1.获取了当前环境中未更新前的的环境变量
2.将更新后的环境变量添加到Environment中
3.获取更新的环境变量
4.发布EnvironmentChangeEvent事件

ConfigurationPropertiesRebinder

public void rebind() {
		this.errors.clear();
		for (String name : this.beans.getBeanNames()) {
			rebind(name);
		}
	}

	@ManagedOperation
	public boolean rebind(String name) {
		if (!this.beans.getBeanNames().contains(name)) {
			return false;
		}
		if (this.applicationContext != null) {
				Object bean = this.applicationContext.getBean(name);
				if (AopUtils.isAopProxy(bean)) {
					bean = ProxyUtils.getTargetObject(bean);
				}
				if (bean != null) {
					this.applicationContext.getAutowireCapableBeanFactory()
							.destroyBean(bean);
					this.applicationContext.getAutowireCapableBeanFactory()
							.initializeBean(bean, name);
					return true;
				}
			
		}
		return false;
	}

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ConfigurationPropertiesRebinder是一个ApplicationListener，用于相应上述的EnvironmentChangeEvent事件，其核心方法就是上面的rebind方法
这里，就是对 beans这个集合里面的bean先进行销毁，然后再重新初始化就，那再重新初始化的时候就会去Environment中拿到最新的值，所以就完成了配置的刷新
而beans 这个集合里面的内容就是标注@ConfigurationProperties 的bean