ZooKeeper学习笔记—配置管理

为什么80%的码农都做不了架构师&＃xff1f;>>>

最近在工作中&＃xff0c;为了完善公司集群服务的架构&＃xff0c;提高可用性&＃xff0c;降低运维成本&＃xff0c;因此开始学习ZooKeeper。
至于什么是ZooKeeper&＃xff1f;它能做什么&＃xff1f;如何安装ZooKeeper&＃xff1f;我就不一一介绍了&＃xff0c;类似这些资料网上到处都是。我主要是把在开发过程中&＃xff0c;以及个人对ZooKeeper的一些了解记录下来&＃xff0c;大家如果遇到类似场景时&＃xff0c;希望我的文章能够给你提供一些思路。

我使用的ZooKeeper&＃xff08;以下简称&＃xff1a;ZK&＃xff09;客户端是Curator Framework&＃xff0c;是Apache的项目&＃xff0c;它主要的功能是为ZK的客户端使用提供了高可用的封装。在Curator Framework基础上封装的curator-recipes&＃xff0c;实现了很多经典场景。比如&＃xff1a;集群管理&＃xff08;Leader选举&＃xff09;、共享锁、队列、Counter等等。可以总结Curator主要解决以下三类问题&＃xff1a;

封装ZK Client与Server之间的连接处理&＃xff1b;
提供了一套Fluent风格的操作API&＃xff1b;
提供ZK各种应用场景的抽象封装&＃xff1b;

本文主要完成的目标是&＃xff1a;Spring PropertyPlaceholderConfigurer配置文件加载器集成ZooKeeper来实现远程配置读取。

配置管理&＃xff08;Configuration Management&＃xff09;。
在集群服务中&＃xff0c;可能都会遇到一个问题&＃xff1a;那就是当需要修改配置的时候&＃xff0c;必须要对每个实例都进行修改&＃xff0c;这是一个很繁琐的事情&＃xff0c;并且易出错。当然可以使用脚本来解决&＃xff0c;但这不是最好的解决办法。

OK&＃xff0c;Let&＃39;s go&＃xff01;

我们先看看项目结构

ZooKeeperPropertyPlaceholderConfigurer.java

继承org.springframework.beans.factory.config.PropertyPlaceholderConfigurer&＃xff0c;重写processProperties(beanFactoryToProcess, props)来完成远端配置加载的实现

package org.bigmouth.common.zookeeper.config.spring;import java.io.UnsupportedEncodingException; import java.util.Properties;import org.apache.commons.lang.StringUtils; import org.bigmouth.common.zookeeper.config.Config; import org.bigmouth.common.zookeeper.config.ZooKeeperConfig; import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;public class ZooKeeperPropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {public static final String PATH &＃61; "zoo.paths";&＃64;Overrideprotected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props)throws BeansException {super.processProperties(beanFactoryToProcess, props);try {fillCustomProperties(props);System.out.println(props);}catch (Exception e) {// Ignoree.printStackTrace();}}private void fillCustomProperties(Properties props) throws Exception {byte[] data &＃61; getData(props);fillProperties(props, data);}private void fillProperties(Properties props, byte[] data) throws UnsupportedEncodingException {String cfg &＃61; new String(data, "UTF-8");if (StringUtils.isNotBlank(cfg)) {// 完整的应该还需要处理&＃xff1a;多条配置、value中包含&＃61;、忽略#号开头String[] cfgItem &＃61; StringUtils.split(cfg, "&＃61;");props.put(cfgItem[0], cfgItem[1]);}}private byte[] getData(Properties props) throws Exception {String path &＃61; props.getProperty(PATH);Config config &＃61; new ZooKeeperConfig();return config.getConfig(path);}}

Config.java

配置操作接口

package org.bigmouth.common.zookeeper.config;public interface Config {byte[] getConfig(String path) throws Exception; }

Startup.java

程序启动入口

package org.bigmouth.common.zookeeper.config;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Startup {public static void main(String[] args) {new ClassPathXmlApplicationContext("classpath:/config/applicationContext.xml");}}

ZooKeeperConfig.java

配置操作接口ZooKeeper的实现

package org.bigmouth.common.zookeeper.config;import org.apache.curator.framework.CuratorFramework; import org.apache.zookeeper.data.Stat;public class ZooKeeperConfig implements Config {&＃64;Overridepublic byte[] getConfig(String path) throws Exception {CuratorFramework client &＃61; ZooKeeperFactory.get();if (!exists(client, path)) {throw new RuntimeException("Path " &＃43; path &＃43; " does not exists.");}return client.getData().forPath(path);}private boolean exists(CuratorFramework client, String path) throws Exception {Stat stat &＃61; client.checkExists().forPath(path);return !(stat &＃61;&＃61; null);}}

ZooKeeperFactory.java

管理ZooKeeper客户端连接

package org.bigmouth.common.zookeeper.config;import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry;public class ZooKeeperFactory {public static final String CONNECT_STRING &＃61; "172.16.3.42:2181,172.16.3.65:2181,172.16.3.24:2181";public static final int MAX_RETRIES &＃61; 3;public static final int BASE_SLEEP_TIMEMS &＃61; 3000;public static final String NAME_SPACE &＃61; "cfg";public static CuratorFramework get() {RetryPolicy retryPolicy &＃61; new ExponentialBackoffRetry(BASE_SLEEP_TIMEMS, MAX_RETRIES);CuratorFramework client &＃61; CuratorFrameworkFactory.builder().connectString(CONNECT_STRING).retryPolicy(retryPolicy).namespace(NAME_SPACE).build();client.start();return client;} }

applicationContext.xml

配置加载器使用我们自己创建的ZooKeeperPropertyPlaceholderConfigurer&＃xff0c;因为它重写了processProperties方法。这个方法里会去读取远程配置。

classpath:application.properties

application.properties

项目配置文件&＃xff0c;里面除了配置ZooKeeper服务器地址和读取的节点以外&＃xff0c;其他所有的配置都应该保存在ZooKeeper中。

zoo.paths&＃61;/properties

设置ZooKeeper数据

登录ZooKeeper中为节点 /cfg/properties 添加一条配置项&＃xff1a;

如图所示&＃xff1a;我创建了一个节点 /cfg/properties 并设置内容为&＃xff1a;jdbc.driver&＃61;org.postgresql.Driver

运行Startup.java

OK 了&＃xff0c;zoo.paths是本地application.properties文件中的&＃xff0c;jdbc.driver是远程ZooKeeper服务器中的。

项目中需要依赖的jar包

commons-langcommons-lang2.4 org.springframeworkspring-core3.0.3.RELEASE org.springframeworkspring-context3.0.3.RELEASE org.springframeworkspring-tx3.0.3.RELEASE org.springframeworkspring-context-support3.0.3.RELEASE org.apache.zookeeperzookeeper3.4.6 org.apache.curatorcurator-framework2.4.2 org.apache.curatorcurator-recipes2.4.2