二、stormkafka之ZkBrokerReader

/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements.  See the NOTICE file * distributed with this work for additional information * regarding copyright ownership.  The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License.  You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package storm.kafka.trident;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import storm.kafka.DynamicBrokersReader;import storm.kafka.ZkHosts;import java.util.Map;public class ZkBrokerReader implements IBrokerReader {    public static final Logger LOG = LoggerFactory.getLogger(ZkBrokerReader.class);    GlobalPartitionInformation cachedBrokers;    DynamicBrokersReader reader;    long lastRefreshTimeMs;    long refreshMillis;    public ZkBrokerReader(Map conf, String topic, ZkHosts hosts) {        try {            reader = new DynamicBrokersReader(conf, hosts.brokerZkStr, hosts.brokerZkPath, topic);            cachedBrokers = reader.getBrokerInfo();            lastRefreshTimeMs = System.currentTimeMillis();            refreshMillis = hosts.refreshFreqSecs * 1000L;        } catch (java.net.SocketTimeoutException e) {            LOG.warn("Failed to update brokers", e);        }    }    /**     * 获取当前的kafka服务器列表     * @return     */    @Override    public GlobalPartitionInformation getCurrentBrokers() {        long currTime = System.currentTimeMillis();        if (currTime > lastRefreshTimeMs + refreshMillis) {            try {                LOG.info("brokers need refreshing because " + refreshMillis + "ms have expired");                cachedBrokers = reader.getBrokerInfo();                lastRefreshTimeMs = currTime;            } catch (java.net.SocketTimeoutException e) {                LOG.warn("Failed to update brokers", e);            }        }        return cachedBrokers;    }    @Override    public void close() {        reader.close();    }}