( 转载 )Zookeeper KeeperErrorCode = ConnectionLoss
服务启动时发现报如下错误：
org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss
error是在调用zk.exists（）时抛出的。
于是开始google，发现问题是原因是：new zookeeper之后，zookeeper的还没有连接好，就去调用，当然会抛错。
继续查找资料，比较优雅的解决方案为如下：
waitUntilConnected(zooKeeper)；
public static void waitUntilConnected(ZooKeeper zooKeeper) {
CountDownLatch connectedLatch = new CountDownLatch(1);
Watcher watcher = new ConnectedWatcher(connectedLatch);
zooKeeper.register(watcher);
if (States.CONNECTING == zooKeeper.getState()) {
try {
connectedLatch.await();
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
}
}
static class ConnectedWatcher implements Watcher {
private CountDownLatch connectedLatch;
ConnectedWatcher(CountDownLatch connectedLatch) {
this.connectedLatch = connectedLatch;
}
@Override
public void process(WatchedEvent event) {
if (event.getState() == KeeperState.SyncConnected) {
connectedLatch.countDown();
}
}
}