老王讲自制RPC框架.(三.ZOOKEEPER）

(#)定义
Zookeeper 分布式服务框架是 Apache Hadoop 的一个子项目，它主要是用来解决分布式应用中经常遇到的一些数据管理问题，如：统一命名服务、状态同步服务、集群
管理、分布式应用配置项的管理

(#)使用
配置zk客户端我就不多说了，这个网上一找一堆，我主要说一下就是，自己玩玩的话，没必要搭建一个集群，用一台基本问题不大，在此假设集群已经搭建完成了
需要引入zk client的jar包

(#)code

  private Logger logger = LoggerFactory.getLogger(ServiceRepository.class);
    @Value("${session.timeout}")
    private int SESSION_TIMEOUT;
    @Value("${registry.address}")
    private String CONNECT_STRING;
    @Value("${repository.path}")
    private String RPC_PATH;
    private ZooKeeper zooKeeper = null;
    private CountDownLatch latch = new CountDownLatch(1);

    private void createConnect() {
        releaseConnection();
        try {
            zooKeeper = new ZooKeeper(CONNECT_STRING, SESSION_TIMEOUT,
                    new Watcher() {
                        public void process(WatchedEvent event) {
                            logger.info("receive message :{}" + event.getState());
                            latch.countDown();
                        }
                    });
            latch.await();
        } catch (IOException e) {
            logger.error("create异常信息:{}", e);
        } catch (InterruptedException e) {
            logger.error("create异常信息:{}", e);
        }
        ;
    }

    private void releaseConnection() {
        if (zooKeeper != null) {
            try {
                zooKeeper.close();
            } catch (InterruptedException e) {
                logger.error("release异常信息:{}", e);
            }
        }
    }

    private boolean createPath(String path, String data) {
        try {
            zooKeeper.create(path, data.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        } catch (KeeperException e) {
            logger.error("create异常信息:{}", e);
        } catch (InterruptedException e) {
            logger.error("create异常信息:{}", e);
        }
        return true;
    }

    public String readData(String path) {
        try {
            return new String(zooKeeper.getData(path, false, null));
        } catch (KeeperException e) {
            logger.error("read异常信息:{}", e);
            return "";
        } catch (InterruptedException e) {
            logger.error("read异常信息:{}", e);
            return "";
        }
    }

    public boolean writeData(String path, String data) {
        try {
            zooKeeper.setData(path, data.getBytes(), -1);
        } catch (KeeperException e) {
            logger.error("write异常信息:{}", e);
        } catch (InterruptedException e) {
            logger.error("write异常信息:{}", e);
        }
        return false;
    }

    public void deleteNode(String path) {
        try {
            zooKeeper.delete(path, -1);
        } catch (KeeperException e) {
            logger.error("delete异常信息:{}", e);
        } catch (InterruptedException e) {
            logger.error("delete异常信息:{}", e);
        }
    }
}