motan源码解读：注册中心zookeeper(2)

      上文大概讲解了利用zookeeper如何实现注册中心的。本文主要是从源码角度说明下。代码都在模块motan-registry-zookeeper中，其实在在这个模块中就3个类。

•    ZkNodeType: 跟上文的图中的节点类型是对应的

enum ZkNodeType {
    AVAILABLE_SERVER,
    UNAVAILABLE_SERVER,
    CLIENT
}

• ZookeeperRegistryFactory：顾名思义

• zookeeper注册中心的注册工厂ZookeeperRegistry

   最重要的就是创建节点

@Override
    protected void doRegister(URL url) {
        try {
            // 防止旧节点未正常注销
            removeNode(url, ZkNodeType.AVAILABLE_SERVER);
            removeNode(url, ZkNodeType.UNAVAILABLE_SERVER);
            createNode(url, ZkNodeType.UNAVAILABLE_SERVER);
        } catch (Throwable e) {
            throw new MotanFrameworkException(String.format("Failed to register %s to zookeeper(%s), cause: %s", url, getUrl(), e.getMessage()));
        }
    }

    还有client对server列表的监听：注释很多，自己看。

 @Override
    protected void doSubscribe(final URL url, final NotifyListener notifyListener) {
        try {
            ConcurrentHashMap<NotifyListener, IZkChildListener> childChangeListeners = urlListeners.get(url);
            if (childChangeListeners == null) {
                urlListeners.putIfAbsent(url, new ConcurrentHashMap<NotifyListener, IZkChildListener>());
                childChangeListeners = urlListeners.get(url);
            }
            IZkChildListener zkChildListener = childChangeListeners.get(notifyListener);
            if (zkChildListener == null) {
                childChangeListeners.putIfAbsent(notifyListener, new IZkChildListener() {
                    @Override
                    public void handleChildChange(String parentPath, List<String> currentChilds) {
                        ZookeeperRegistry.this.notify(url, notifyListener, nodeChildsToUrls(parentPath, currentChilds));
                        LoggerUtil.info(String.format("[ZookeeperRegistry] service list change: path=%s, currentChilds=%s", parentPath, currentChilds.toString()));
                    }
                });
                zkChildListener = childChangeListeners.get(notifyListener);
            }

            // 防止旧节点未正常注销
            removeNode(url, ZkNodeType.CLIENT);
            createNode(url, ZkNodeType.CLIENT);

            // 订阅server节点，并获取当前可用server
            String serverTypePath = toNodeTypePath(url, ZkNodeType.AVAILABLE_SERVER);
            List<String> currentChilds = zkClient.subscribeChildChanges(serverTypePath, zkChildListener);
            LoggerUtil.info(String.format("[ZookeeperRegistry] subscribe: path=%s, info=%s", toNodePath(url, ZkNodeType.AVAILABLE_SERVER), url.toFullStr()));
            notify(url, notifyListener, nodeChildsToUrls(serverTypePath, currentChilds));
        } catch (Throwable e) {
            throw new MotanFrameworkException(String.format("Failed to subscribe %s to zookeeper(%s), cause: %s", url, getUrl(), e.getMessage()));
        }
    }

 http://www.cnblogs.com/scott19820130/p/4940066.html