public interface Event {}

abstract public void process(WatchedEvent event);

        public enum KeeperState { // 事件发生时Zookeeper的状态/** Unused, this state is never generated by the server */@Deprecated// 未知状态，不再使用，服务器不会产生此状态Unknown (-1), /** The client is in the disconnected state - it is not connected* to any server in the ensemble. */// 断开Disconnected (0),/** Unused, this state is never generated by the server */@Deprecated// 未同步连接，不再使用，服务器不会产生此状态NoSyncConnected (1),/** The client is in the connected state - it is connected* to a server in the ensemble (one of the servers specified* in the host connection parameter during ZooKeeper client* creation). */// 同步连接状态SyncConnected (3),/*** Auth failed state*/// 认证失败状态AuthFailed (4),/*** The client is connected to a read-only server, that is the* server which is not currently connected to the majority.* The only operations allowed after receiving this state is* read operations.* This state is generated for read-only clients only since* read/write clients aren't allowed to connect to r/o servers.*/// 只读连接状态ConnectedReadOnly (5),/*** SaslAuthenticated: used to notify clients that they are SASL-authenticated,* so that they can perform Zookeeper actions with their SASL-authorized permissions.*/// SASL认证通过状态SaslAuthenticated(6),/** The serving cluster has expired this session. The ZooKeeper* client connection (the session) is no longer valid. You must* create a new client connection (instantiate a new ZooKeeper* instance) if you with to access the ensemble. */// 过期状态Expired (-112);// 代表状态的整形值private final int intValue;     // Integer representation of value// for sending over wire// 构造函数KeeperState(int intValue) {this.intValue = intValue;}// 返回整形值public int getIntValue() {return intValue;}// 从整形值构造相应的状态public static KeeperState fromInt(int intValue) {switch(intValue) {case   -1: return KeeperState.Unknown;case    0: return KeeperState.Disconnected;case    1: return KeeperState.NoSyncConnected;case    3: return KeeperState.SyncConnected;case    4: return KeeperState.AuthFailed;case    5: return KeeperState.ConnectedReadOnly;case    6: return KeeperState.SaslAuthenticated;case -112: return KeeperState.Expired;default:throw new RuntimeException("Invalid integer value for conversion to KeeperState");}}}

        public enum EventType { // 事件类型// 无None (-1),// 结点创建NodeCreated (1),// 结点删除NodeDeleted (2),// 结点数据变化NodeDataChanged (3),// 结点子节点变化NodeChildrenChanged (4);// 代表事件类型的整形 private final int intValue;     // Integer representation of value// for sending over wire// 构造函数EventType(int intValue) {this.intValue = intValue;}// 返回整形public int getIntValue() {return intValue;}// 从整形构造相应的事件public static EventType fromInt(int intValue) {switch(intValue) {case -1: return EventType.None;case  1: return EventType.NodeCreated;case  2: return EventType.NodeDeleted;case  3: return EventType.NodeDataChanged;case  4: return EventType.NodeChildrenChanged;default:throw new RuntimeException("Invalid integer value for conversion to EventType");}}           }}

public class WatchedEvent {// Zookeeper的状态final private KeeperState keeperState;// 事件类型final private EventType eventType;// 事件所涉及节点的路径private String path;
}

    public WatchedEvent(EventType eventType, KeeperState keeperState, String path) {// 初始化属性this.keeperState = keeperState;this.eventType = eventType;this.path = path;}

    public WatchedEvent(WatcherEvent eventMessage) {// 从eventMessage中取出相应属性进行赋值keeperState = KeeperState.fromInt(eventMessage.getState());eventType = EventType.fromInt(eventMessage.getType());path = eventMessage.getPath();}

public Set<Watcher> materialize(Watcher.Event.KeeperState state,Watcher.Event.EventType type, String path);

    private static class ZKWatchManager implements ClientWatchManager {// 数据变化的Watchersprivate final Map<String, Set<Watcher>> dataWatches =new HashMap<String, Set<Watcher>>();// 节点存在与否的Watchersprivate final Map<String, Set<Watcher>> existWatches =new HashMap<String, Set<Watcher>>();// 子节点变化的Watchersprivate final Map<String, Set<Watcher>> childWatches =new HashMap<String, Set<Watcher>>();}

        public Set<Watcher> materialize(Watcher.Event.KeeperState state,Watcher.Event.EventType type,String clientPath){// 新生成结果Watcher集合Set<Watcher> result = new HashSet<Watcher>();switch (type) { // 确定事件类型case None: // 无类型// 添加默认Watcher
                result.add(defaultWatcher);// 是否需要清空(提取对zookeeper.disableAutoWatchReset字段进行配置的值、Zookeeper的状态是否为同步连接)boolean clear = ClientCnxn.getDisableAutoResetWatch() &&state != Watcher.Event.KeeperState.SyncConnected;synchronized(dataWatches) { // 同步块for(Set<Watcher> ws: dataWatches.values()) {// 添加至结果集合
                        result.addAll(ws);}if (clear) { // 是否需要清空
                        dataWatches.clear();}}synchronized(existWatches) { // 同步块 for(Set<Watcher> ws: existWatches.values()) {// 添加至结果集合
                        result.addAll(ws);}if (clear) { // 是否需要清空
                        existWatches.clear();}}synchronized(childWatches) { // 同步块for(Set<Watcher> ws: childWatches.values()) {// 添加至结果集合
                        result.addAll(ws);}if (clear) { // 是否需要清空
                        childWatches.clear();}}// 返回结果return result;case NodeDataChanged: // 节点数据变化case NodeCreated: // 创建节点synchronized (dataWatches) { // 同步块// 移除clientPath对应的Watcher后全部添加至结果集合
                    addTo(dataWatches.remove(clientPath), result);}synchronized (existWatches) { // 移除clientPath对应的Watcher后全部添加至结果集合
                    addTo(existWatches.remove(clientPath), result);}break;case NodeChildrenChanged: // 节点子节点变化synchronized (childWatches) {// 移除clientPath对应的Watcher后全部添加至结果集合
                    addTo(childWatches.remove(clientPath), result);}break;case NodeDeleted: // 删除节点synchronized (dataWatches) { // 移除clientPath对应的Watcher后全部添加至结果集合
                    addTo(dataWatches.remove(clientPath), result);}// XXX This shouldn't be needed, but just in casesynchronized (existWatches) {// 移除clientPath对应的WatcherSet<Watcher> list = existWatches.remove(clientPath);if (list != null) {// 移除clientPath对应的Watcher后全部添加至结果集合
                        addTo(existWatches.remove(clientPath), result);LOG.warn("We are triggering an exists watch for delete! Shouldn't happen!");}}synchronized (childWatches) {// 移除clientPath对应的Watcher后全部添加至结果集合
                    addTo(childWatches.remove(clientPath), result);}break;default: // 缺省处理String msg = "Unhandled watch event type " + type+ " with state " + state + " on path " + clientPath;LOG.error(msg);throw new RuntimeException(msg);}// 返回结果集合return result;}}