Apollo热发布配置

一、背景

项目中需要用的阿波罗热发布，一种是利用注解ApolloConfigChangeListener的方式,可用如下配置就可。


@Component
@Slf4j
public class ApolloRefreshConfig2  implements ApplicationContextAware{

    @Autowired
    private RefreshScope refreshScope;
    private ApplicationContext applicationContext;

    @ApolloConfigChangeListener()
    public void onChange(ConfigChangeEvent changeEvent) {
        refreshProperties(changeEvent);
    }

    private void refreshProperties(ConfigChangeEvent changeEvent) {
        this.applicationContext.publishEvent(new EnvironmentChangeEvent(changeEvent.changedKeys()));
        refreshScope.refreshAll();
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
}

可是在测试中发现热部署并没有更新，后查看注解ApolloConfigChangeListener，发现如果不指定value值则默认namespace为 application。而我们项目中并没有使用application，而是拆分出来更多的命名空间；所以并不适用，需要指定value，如value={"edl-pub-service-common","Java.bmc-local-eureka","Java.bmc-pub-mysql","Java.bmc-redis","Java.bmc-rabbitmq","Java.bmc-httplog"};

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Documented
public @interface ApolloConfigChangeListener {
  /**
   * Apollo namespace for the config, if not specified then default to application
   */
  String[] value() default {ConfigConsts.NAMESPACE_APPLICATION};
  String[] interestedKeys() default {};
  String[] interestedKeyPrefixes() default {};
}

这里放一下我们的配置文件

# 应用ID(在Apollo服务端新增项目添加的应用ID)
app:
  id: bmc
# apollo-configservice地址
apollo:
  meta: http://10.197.236.187:7070
  bootstrap:
    enabled: true
    namespaces: edl-pub-service-common,Java.bmc-local-eureka,Java.bmc-pub-mysql,Java.bmc-redis,Java.bmc-rabbitmq,Java.bmc-httplog
    eagerLoad:
      enabled: true

可以不想再value中硬编码，那么问题来了：能否将value中的动态配置，比如读取配置文件中的数据？

二、尝试

1.@ApolloConfigChangeListener()注解的value直接设置EL表达式，结果------失败。

如下代码设置

    @ApolloConfigChangeListener(value = "${apollo.bootstrap.namespacesArr}")
    public void onChange(ConfigChangeEvent changeEvent) {
        refreshProperties(changeEvent);
    }

经过debug尝试，发现Apollo会默认注册 AutoUpdateConfigChangeListener监听器，如果扫描到ApolloConfigChangeListener注解也会注册到监听器中（源码见com.ctrip.framework.apollo.spring.annotation.ApolloAnnotationProcessor）,可是在获取此注解的时候并没有判断是不是EL表达式，所以你传入 ${apollo.bootstrap.namespacesArr} ，那么 namespace 的名称就是$ {apollo.bootstrap.namespacesArr}；代码如下

@Override
  protected void processMethod(final Object bean, String beanName, final Method method) {
    ApolloConfigChangeListener annotation = AnnotationUtils
        .findAnnotation(method, ApolloConfigChangeListener.class);
    if (annotation == null) {
      return;
    }
    Class<?>[] parameterTypes = method.getParameterTypes();
    Preconditions.checkArgument(parameterTypes.length == 1,
        "Invalid number of parameters: %s for method: %s, should be 1", parameterTypes.length,
        method);
    Preconditions.checkArgument(ConfigChangeEvent.class.isAssignableFrom(parameterTypes[0]),
        "Invalid parameter type: %s for method: %s, should be ConfigChangeEvent", parameterTypes[0],
        method);

    ReflectionUtils.makeAccessible(method);
// *********** 重点在这里 ，直接读取 ***********
    String[] namespaces = annotation.value();
    String[] annotatedInterestedKeys = annotation.interestedKeys();
    String[] annotatedInterestedKeyPrefixes = annotation.interestedKeyPrefixes();
    ConfigChangeListener configChangeListener = new ConfigChangeListener() {
      @Override
      public void onChange(ConfigChangeEvent changeEvent) {
        ReflectionUtils.invokeMethod(method, bean, changeEvent);
      }
    };

    Set<String> interestedKeys = annotatedInterestedKeys.length > 0 ? Sets.newHashSet(annotatedInterestedKeys) : null;
    Set<String> interestedKeyPrefixes = annotatedInterestedKeyPrefixes.length > 0 ? Sets.newHashSet(annotatedInterestedKeyPrefixes) : null;

    for (String namespace : namespaces) {
      Config config = ConfigService.getConfig(namespace);

      if (interestedKeys == null && interestedKeyPrefixes == null) {
        config.addChangeListener(configChangeListener);
      } else {
        config.addChangeListener(configChangeListener, interestedKeys, interestedKeyPrefixes);
      }
    }
  }

所以该我们配置文件的属性改变因为不是指定的namespaces就不会更新。

2.利用反射动态修改@ApolloConfigChangeListener()注解的value，将value赋值为配置的属性，结果------失败。

此方法明显行不通，因为ApolloAnnotationProcessor中每次获取的ApolloConfigChangeListener 开始设置的值，而不是通过我们反射获取的值，反射的主要代码如下

 try {
                method = ApolloRefreshConfig.class.getMethod("onChange", ConfigChangeEvent.class);
                ApolloConfigChangeListener annotation = method.getAnnotation(ApolloConfigChangeListener.class);
                InvocationHandler invocationHandler = Proxy.getInvocationHandler(annotation);
                Field value = invocationHandler.getClass().getDeclaredField("memberValues");
                value.setAccessible(true);
                Map<String, String[]> stringObjectMap = (Map<String, String[]>) value.get(invocationHandler);
                stringObjectMap.put("value", namespacesArr);
            } catch (NoSuchMethodException e) {
                e.printStackTrace();
            } catch (NoSuchFieldException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }

3.新写监听器，加入监听器集合中，结果------失败。

因为始终读取不到配置文件，猜测跟ApolloProcessor 继承 BeanPostProcessor有关吧。

@Component
@Slf4j
public class ApolloRefreshListener extends ApolloProcessor implements ApplicationContextAware {

    @Autowired
    private RefreshScope refreshScope;

    @Value("${apollo.bootstrap.namespaces}")
    private String namespaces;

    private ApplicationContext applicationContext;
    @Autowired
    private ConfigPropertySourceFactory configPropertySourceFactory;

/*    @PostConstruct
    private void init(){
        List<String> namespacesList = Lists.newArrayList();
        Splitter.on(",").omitEmptyStrings().split(namespaces).forEach(item -> namespacesList.add(item));
        namespacesArr = new String[namespacesList.size()];
    }*/


    @Override
    protected void processField(Object bean, String beanName, Field field) {
        ApolloConfig annotation = AnnotationUtils.getAnnotation(field, ApolloConfig.class);
        if (annotation == null) {
            return;
        }

        Preconditions.checkArgument(Config.class.isAssignableFrom(field.getType()),
                "Invalid type: %s for field: %s, should be Config", field.getType(), field);

        String namespace = annotation.value();
        Config config = ConfigService.getConfig(namespace);

        ReflectionUtils.makeAccessible(field);
        ReflectionUtils.setField(field, bean, config);
    }

    @Override
    protected void processMethod(final Object bean, String beanName, final Method method) {

        ApolloRefreshConfig apolloRefreshListener = new ApolloRefreshConfig();
        List<ConfigPropertySource> allConfigPropertySources = configPropertySourceFactory.getAllConfigPropertySources();
        for (ConfigPropertySource allConfigPropertySource : allConfigPropertySources) {
            Config config = ConfigService.getConfig(allConfigPropertySource.getName());
            config.addChangeListener(apolloRefreshListener);
        }
    }


    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

}

三、结论

暂无解决办法，目前只有写死。