上一节讲了从我们SpringBoot项目同步数据到SoulAdmin并将数据持久化到数据库中，这一节

在数据持久化到数据库中之后，SoulAdmin会通过Spring的ApplicationEventPublisher发送一个事件变更事件，继承自org.springframework.context.ApplicationEvent

//org.dromara.soul.admin.listener.DataChangedEvent#DataChangedEvent
public class DataChangedEvent extends ApplicationEvent {

    private DataEventTypeEnum eventType;

    private ConfigGroupEnum groupKey;

    /**
     * Instantiates a new Data changed event.
     *
     * @param groupKey the group key
     * @param type     the type
     * @param source   the source
     */
    public DataChangedEvent(final ConfigGroupEnum groupKey, final DataEventTypeEnum type, final List<?> source) {
        super(source);
        this.eventType = type;
        this.groupKey = groupKey;
    }

    /**
     * Gets event type.
     *
     * @return the event type
     */
    DataEventTypeEnum getEventType() {
        return eventType;
    }

    @Override
    public List<?> getSource() {
        return (List<?>) super.getSource();
    }

    /**
     * Gets group key.
     *
     * @return the group key
     */
    public ConfigGroupEnum getGroupKey() {
        return this.groupKey;
    }

}

DataChangedEvent存在两个属性，eventType

//org.dromara.soul.common.enums.DataEventTypeEnum
//对应着事件的类型
public enum DataEventTypeEnum {

    /**
     * delete event.
     */
    DELETE,

    /**
     * insert event.
     */
    CREATE,

    /**
     * update event.
     */
    UPDATE,

    /**
     * REFRESH data event type enum.
     */
    REFRESH,

    /**
     * Myself data event type enum.
     */
    MYSELF;
}

//org.dromara.soul.common.enums.ConfigGroupEnum
//对应着配置分组，现在总共支持 APP_AUTH：配置，PLUGIN：插件，RULE：规则，SELECTOR：选择器，META_DATA：元数据 
public enum ConfigGroupEnum {

    /**
     * App auth config group enum.
     */
    APP_AUTH,

    /**
     * Plugin config group enum.
     */
    PLUGIN,

    /**
     * Rule config group enum.
     */
    RULE,

    /**
     * Selector config group enum.
     */
    SELECTOR,

    /**
     * Meta data config group enum.
     */
    META_DATA;
}

接下来通过查询org.dromara.soul.admin.listener.DataChangedEvent调用他的地方。定位到DataChangedEventDispatcher

DataChangedEventDispatcher 实现了ApplicationListener并且接收DataChangedEvent事件，通过GroupKey的类型做不同处理

//org.dromara.soul.admin.listener.DataChangedEventDispatcher
public class DataChangedEventDispatcher implements ApplicationListener<DataChangedEvent>, InitializingBean {
    private ApplicationContext applicationContext;

    private List<DataChangedListener> listeners;

    public DataChangedEventDispatcher(final ApplicationContext applicationContext) {
        this.applicationContext = applicationContext;
    }

  // 监听DataChangedEvent，并根据ConfigGroupEnum类型进行不同的处理
    @Override
    @SuppressWarnings("unchecked")
    public void onApplicationEvent(final DataChangedEvent event) {
        for (DataChangedListener listener : listeners) {
            switch (event.getGroupKey()) {
                case APP_AUTH:
                    listener.onAppAuthChanged((List<AppAuthData>) event.getSource(), event.getEventType());
                    break;
                case PLUGIN:
                    listener.onPluginChanged((List<PluginData>) event.getSource(), event.getEventType());
                    break;
                case RULE:
                    listener.onRuleChanged((List<RuleData>) event.getSource(), event.getEventType());
                    break;
                case SELECTOR:
                    listener.onSelectorChanged((List<SelectorData>) event.getSource(), event.getEventType());
                    break;
                case META_DATA:
                    listener.onMetaDataChanged((List<MetaData>) event.getSource(), event.getEventType());
                    break;
                default:
                    throw new IllegalStateException("Unexpected value: " + event.getGroupKey());
            }
        }
    }

  // 将Spring代理的DataChangedListener注入到当前类的listeners
    @Override
    public void afterPropertiesSet() {
        Collection<DataChangedListener> listenerBeans = applicationContext.getBeansOfType(DataChangedListener.class).values();
        this.listeners = Collections.unmodifiableList(new ArrayList<>(listenerBeans));
    }
}

接口DataChangedListener不同实现类有如下：

image.png

即对应了现在Soul的四种数据同步方式：http长轮训，Websocket，Nacos，Zookeeper

1.Zookeeper方式很简单，就是依赖Zookeeper的watch机制，SoulAdmin在启动的时候将数据全量同步到Zookeeper，之后变化增量更新数据。

image.png

2. Websocket和Zookeeper机制有点类似，将网关与admin建立好websocket连接时，admin会推送一次全量数据，后续如果配置数据发生变更，则将增量数据通过websocket主动推送给soul-web。