分布式apollo简介

Apollo(阿波罗)是携程框架部门研发的开源配置管理中心，能够集中化管理应用不同环境、不同集群的配置，配置修改后能够实时推送到应用端，并且具备规范的权限、流程治理等特性。

本文主要介绍如何使用apollo与springboot实现动态刷新配置，如果之前不了解apollo可以查看如下文档

https://github.com/ctripcorp/apollo

学习了解一下apollo，再来查看本文

正文

apollo与spring实现动态刷新配置本文主要演示2种刷新，一种基于普通字段刷新、一种基于bean上使用了@ConfigurationProperties刷新

1、普通字段刷新

a、pom.xml配置

        com.ctrip.framework.apollo            apollo-client            1.6.0

b、客户端配置AppId，Apollo Meta Server

此配置有多种方法，本示例直接在application.yml配置，配置内容如下

app:  id: ${spring.application.name}apollo:  meta: http://192.168.88.128:8080,http://192.168.88.129:8080  bootstrap:    ena

c、项目中启动类上加上@EnableApolloConfig注解，形如下

@SpringBootApplication@EnableApolloConfig(value = {"application","user.properties","product.properties","order.properties"})public class ApolloApplication {    public static void main(String[] args) {        SpringApplication.run(ApolloApplication.class, args);    }}

@EnableApolloConfig不一定要加在启动类上，加在被spring管理的类上即可

d、在需刷新的字段上配置@Value注解，形如

    @Value("${hello}")    private String hello;

通过以上三步就可以实现普通字段的动态刷新

2.bean使用@ConfigurationProperties动态刷新

bean使用@ConfigurationProperties注解目前还不支持自动刷新，得编写一定的代码实现刷新。目前官方提供2种刷新方案

• 基于RefreshScope实现刷新
• 基于EnvironmentChangeEvent实现刷新
• 本文再提供一种，当bean上如果使用了@ConditionalOnProperty如何实现刷新

a、基于RefreshScope实现刷新

1、pom.xml要额外引入

    org.springframework.cloud            spring-cloud-context            2.0.3.RELEASE

2、bean上使用@RefreshScope注解

@Component@ConfigurationProperties(prefix = "product")@Data@AllArgsConstructor@NoArgsConstructor@Builder@RefreshScopepublic class Product {    private Long id;    private String productName;    private BigDecimal price;}

3、利用RefreshScope搭配@ApolloConfigChangeListener监听实现bean的动态刷新，其代码实现如下

 @ApolloConfigChangeListener(value="product.properties",interestedKeyPrefixes = {"product."})    private void refresh(ConfigChangeEvent changeEvent){        refreshScope.refresh("product");        PrintChangeKeyUtils.printChange(changeEvent);    }

b、基于EnvironmentChangeEvent实现刷新

利用spring的事件驱动配合@ApolloConfigChangeListener监听实现bean的动态刷新，其代码如下

@Component@Slf4jpublic class UserPropertiesRefresh implements ApplicationContextAware {    private ApplicationContext applicationContext;    @ApolloConfigChangeListener(value="user.properties",interestedKeyPrefixes = {"user."})    private void refresh(ConfigChangeEvent changeEvent){        applicationContext.publishEvent(new EnvironmentChangeEvent(changeEvent.changedKeys()));        PrintChangeKeyUtils.printChange(changeEvent);    }    @Override    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {        this.applicationContext = applicationContext;    }}

c、当bean上有@ConditionalOnProperty如何实现刷新

当bean上有@ConditionalOnProperty注解时，上述的两种方案可以说失效了，因为@ConditionalOnProperty是一个条件注解，当不满足条件注解时，bean是没法注册到spring容器中的。如果我们要实现此种情况的下的动态刷新，我们就得自己手动注册或者销毁bean了。其实现流程如下

1、当满足条件注解时，则手动创建bean，然后配合@ApolloConfigChangeListener监听该bean的属性变化。当该bean属性有变化时，手动把属性注入bean。同时刷新依赖该bean的其他bean

2、当不满足条件注解时，则手动从spring容器中移除bean，同时刷新依赖该bean的其他bean

其刷新核心代码如下

public class OrderPropertiesRefresh implements ApplicationContextAware {    private ApplicationContext applicationContext;    @ApolloConfig(value = "order.properties")    private Config config;    @ApolloConfigChangeListener(value="order.properties",interestedKeyPrefixes = {"order."},interestedKeys = {"model.isShowOrder"})    private void refresh(ConfigChangeEvent changeEvent){        for (String basePackage : listBasePackages()) {            Set conditionalClasses = ClassScannerUtils.scan(basePackage, ConditionalOnProperty.class);            if(!CollectionUtils.isEmpty(conditionalClasses)){                for (Class conditionalClass : conditionalClasses) {                    ConditionalOnProperty conditionalOnProperty = (ConditionalOnProperty) conditionalClass.getAnnotation(ConditionalOnProperty.class);                    String[] conditionalOnPropertyKeys = conditionalOnProperty.name();                    String beanChangeCondition = this.getChangeKey(changeEvent,conditionalOnPropertyKeys);                    String conditionalOnPropertyValue = conditionalOnProperty.havingValue();                    boolean isChangeBean = this.changeBean(conditionalClass, beanChangeCondition, conditionalOnPropertyValue);                    if(!isChangeBean){                        // 更新相应的bean的属性值，主要是存在@ConfigurationProperties注解的bean                        applicationContext.publishEvent(new EnvironmentChangeEvent(changeEvent.changedKeys()));                    }                }            }        }        PrintChangeKeyUtils.printChange(changeEvent);        printAllBeans();    }    /**     * 根据条件对bean进行注册或者移除     * @param conditionalClass     * @param beanChangeCondition bean发生改变的条件     * @param conditionalOnPropertyValue     */    private boolean changeBean(Class conditionalClass, String beanChangeCondition, String conditionalOnPropertyValue) {        boolean isNeedRegisterBeanIfKeyChange = this.isNeedRegisterBeanIfKeyChange(beanChangeCondition,conditionalOnPropertyValue);        boolean isNeedRemoveBeanIfKeyChange = this.isNeedRemoveBeanIfKeyChange(beanChangeCondition,conditionalOnPropertyValue);        String beanName = StringUtils.uncapitalize(conditionalClass.getSimpleName());        if(isNeedRegisterBeanIfKeyChange){            boolean isAlreadyRegisterBean = this.isExistBean(beanName);            if(!isAlreadyRegisterBean){                this.registerBean(beanName,conditionalClass);                return true;            }        }else if(isNeedRemoveBeanIfKeyChange){            this.unregisterBean(beanName);            return true;        }        return false;    }    /**     * bean注册     * @param beanName     * @param beanClass     */    public void registerBean(String beanName,Class beanClass) {        log.info("registerBean->beanName:{},beanClass:{}",beanName,beanClass);        BeanDefinitionBuilder beanDefinitionBurinilder = BeanDefinitionBuilder.genericBeanDefinition(beanClass);        BeanDefinition beanDefinition = beanDefinitionBurinilder.getBeanDefinition();        setBeanField(beanClass, beanDefinition);        getBeanDefinitionRegistry().registerBeanDefinition(beanName,beanDefinition);    }    /**     * 设置bean字段值     * @param beanClass     * @param beanDefinition     */    private void setBeanField(Class beanClass, BeanDefinition beanDefinition) {        ConfigurationProperties configurationProperties = (ConfigurationProperties) beanClass.getAnnotation(ConfigurationProperties.class);        if(ObjectUtils.isNotEmpty(configurationProperties)){            String prefix = configurationProperties.prefix();            for (String propertyName : config.getPropertyNames()) {                String fieldPrefix = prefix + ".";                if(propertyName.startsWith(fieldPrefix)){                    String fieldName = propertyName.substring(fieldPrefix.length());                    String fieldVal = config.getProperty(propertyName,null);                    log.info("setBeanField-->fieldName:{},fieldVal:{}",fieldName,fieldVal);                    beanDefinition.getPropertyValues().add(fieldName,fieldVal);                }            }        }    }    /**     * bean移除     * @param beanName     */    public void unregisterBean(String beanName){        log.info("unregisterBean->beanName:{}",beanName);        getBeanDefinitionRegistry().removeBeanDefinition(beanName);    }    public   T getBean(String name) {        return (T) applicationContext.getBean(name);    }    public   T getBean(Class clz) {        return (T) applicationContext.getBean(clz);    }    public boolean isExistBean(String beanName){        return applicationContext.containsBean(beanName);    }    public boolean isExistBean(Class clz){        try {            Object bean = applicationContext.getBean(clz);            return true;        } catch (BeansException e) {            // log.error(e.getMessage(),e);        }        return false;    }    private boolean isNeedRegisterBeanIfKeyChange(String changeKey,String conditionalOnPropertyValue){        if(StringUtils.isEmpty(changeKey)){            return false;        }        String apolloConfigValue = config.getProperty(changeKey,null);        return conditionalOnPropertyValue.equals(apolloConfigValue);    }    private boolean isNeedRemoveBeanIfKeyChange(String changeKey,String conditionalOnPropertyValue){        if(!StringUtils.isEmpty(changeKey)){            String apolloConfigValue = config.getProperty(changeKey,null);            return !conditionalOnPropertyValue.equals(apolloConfigValue);        }        return false;    }    private boolean isChangeKey(ConfigChangeEvent changeEvent,String conditionalOnPropertyKey){        Set changeKeys = changeEvent.changedKeys();        if(!CollectionUtils.isEmpty(changeKeys) && changeKeys.contains(conditionalOnPropertyKey)){            return true;        }        return false;    }    private String getChangeKey(ConfigChangeEvent changeEvent, String[] conditionalOnPropertyKeys){        if(ArrayUtils.isEmpty(conditionalOnPropertyKeys)){            return null;        }        String changeKey = null;        for (String conditionalOnPropertyKey : conditionalOnPropertyKeys) {            if(isChangeKey(changeEvent,conditionalOnPropertyKey)){                changeKey = conditionalOnPropertyKey;                break;            }        }        return changeKey;    }    private BeanDefinitionRegistry getBeanDefinitionRegistry(){        ConfigurableApplicationContext configurableContext = (ConfigurableApplicationContext) applicationContext;        BeanDefinitionRegistry beanDefinitionRegistry = (DefaultListableBeanFactory) configurableContext.getBeanFactory();        return beanDefinitionRegistry;    }    private List listBasePackages(){        ConfigurableApplicationContext configurableContext = (ConfigurableApplicationContext) applicationContext;        return AutoConfigurationPackages.get(configurableContext.getBeanFactory());    }    @Override    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {        this.applicationContext = applicationContext;    }    public  void printAllBeans() {        String[] beans = applicationContext.getBeanDefinitionNames();        Arrays.sort(beans);        for (String beanName : beans) {            Class> beanType = applicationContext.getType(beanName);            System.out.println(beanType);        }    }}

如果条件注解的值也是配置在apollo上，可能会出现依赖条件注解的bean的其他bean，在项目拉取apollo配置时，就已经注入spring容器中，此时就算条件注解满足条件，则引用该条件注解bean的其他bean，也会拿不到条件注解bean。此时有2种方法解决，一种是在依赖条件注解bean的其他bean注入之前，先手动注册条件注解bean到spring容器中，其核心代码如下

@Component@Slf4jpublic class RefreshBeanFactory implements BeanFactoryPostProcessor {    @Override    public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {        Config config = ConfigService.getConfig("order.properties");        List basePackages = AutoConfigurationPackages.get(configurableListableBeanFactory);        for (String basePackage : basePackages) {            Set conditionalClasses = ClassScannerUtils.scan(basePackage, ConditionalOnProperty.class);            if(!CollectionUtils.isEmpty(conditionalClasses)){                for (Class conditionalClass : conditionalClasses) {                    ConditionalOnProperty conditionalOnProperty = (ConditionalOnProperty) conditionalClass.getAnnotation(ConditionalOnProperty.class);                    String[] conditionalOnPropertyKeys = conditionalOnProperty.name();                    String beanConditionKey = this.getConditionalOnPropertyKey(config,conditionalOnPropertyKeys);                    String conditionalOnPropertyValue = conditionalOnProperty.havingValue();                    this.registerBeanIfMatchCondition((DefaultListableBeanFactory)configurableListableBeanFactory,config,conditionalClass,beanConditionKey,conditionalOnPropertyValue);                }            }        }    }    private void registerBeanIfMatchCondition(DefaultListableBeanFactory beanFactory,Config config,Class conditionalClass, String beanConditionKey, String conditionalOnPropertyValue) {        boolean isNeedRegisterBean = this.isNeedRegisterBean(config,beanConditionKey,conditionalOnPropertyValue);        String beanName = StringUtils.uncapitalize(conditionalClass.getSimpleName());        if(isNeedRegisterBean){                this.registerBean(config,beanFactory,beanName,conditionalClass);        }    }    public void registerBean(Config config,DefaultListableBeanFactory beanFactory, String beanName, Class beanClass) {        log.info("registerBean->beanName:{},beanClass:{}",beanName,beanClass);        BeanDefinitionBuilder beanDefinitionBurinilder = BeanDefinitionBuilder.genericBeanDefinition(beanClass);        BeanDefinition beanDefinition = beanDefinitionBurinilder.getBeanDefinition();        setBeanField(config,beanClass, beanDefinition);        beanFactory.registerBeanDefinition(beanName,beanDefinition);    }    private void setBeanField(Config config,Class beanClass, BeanDefinition beanDefinition) {        ConfigurationProperties configurationProperties = (ConfigurationProperties) beanClass.getAnnotation(ConfigurationProperties.class);        if(ObjectUtils.isNotEmpty(configurationProperties)){            String prefix = configurationProperties.prefix();            for (String propertyName : config.getPropertyNames()) {                String fieldPrefix = prefix + ".";                if(propertyName.startsWith(fieldPrefix)){                    String fieldName = propertyName.substring(fieldPrefix.length());                    String fieldVal = config.getProperty(propertyName,null);                    log.info("setBeanField-->fieldName:{},fieldVal:{}",fieldName,fieldVal);                    beanDefinition.getPropertyValues().add(fieldName,fieldVal);                }            }        }    }    public boolean isNeedRegisterBean(Config config,String beanConditionKey,String conditionalOnPropertyValue){        if(StringUtils.isEmpty(beanConditionKey)){            return false;        }        String apolloConfigValue = config.getProperty(beanConditionKey,null);        return conditionalOnPropertyValue.equals(apolloConfigValue);    }    private String getConditionalOnPropertyKey(Config config, String[] conditionalOnPropertyKeys){        if(ArrayUtils.isEmpty(conditionalOnPropertyKeys)){            return null;        }        String changeKey = null;        for (String conditionalOnPropertyKey : conditionalOnPropertyKeys) {            if(isConditionalOnPropertyKey(config,conditionalOnPropertyKey)){                changeKey = conditionalOnPropertyKey;                break;            }        }        return changeKey;    }    private boolean isConditionalOnPropertyKey(Config config,String conditionalOnPropertyKey){        Set propertyNames = config.getPropertyNames();        if(!CollectionUtils.isEmpty(propertyNames) && propertyNames.contains(conditionalOnPropertyKey)){            return true;        }        return false;    }}

其次利用懒加载的思想，在使用条件注解bean时，使用形如下方法

Order order = (Order) SpringContextUtils.getBean("order");

总结

本文主要介绍了常用的动态刷新，但本文的代码示例实现的功能不局限于此，本文的代码还实现如何通过自定义注解与apollo整合来实现一些业务操作，同时也实现了基于hystrix注解与apollo整合，实现基于线程隔离的动态熔断，感兴趣的朋友可以复制文末链接到浏览器，进行查看

apollo基本上是能满足我们日常的业务开发要求，但是对于一些需求，比如动态刷新线上数据库资源啥，我们还是得做一定的量的改造，好在携程也提供了apollo-use-cases，在里面可以找到常用的使用场景以及示例代码，其链接如下

https://github.com/ctripcorp/apollo-use-cases

感兴趣的朋友，可以查看下。