ZooKeeper配置管理文件

最近在工作中，為了完善公司集群服務的架構，提高可用性，降低運維成本，因此開始學習ZooKeeper。
    至於什么是ZooKeeper？它能做什么？如何安裝ZooKeeper？我就不一一介紹了，類似這些資料網上到處都是。我主要是把在開發過程中，以及個人對ZooKeeper的一些了解記錄下來，大家如果遇到類似場景時，希望我的文章能夠給你提供一些思路。

    我使用的ZooKeeper（以下簡稱：ZK）客戶端是Curator Framework，是Apache的項目，它主要的功能是為ZK的客戶端使用提供了高可用的封裝。在Curator Framework基礎上封裝的curator-recipes，實現了很多經典場景。比如：集群管理（Leader選舉）、共享鎖、隊列、Counter等等。可以總結Curator主要解決以下三類問題：

• 封裝ZK Client與Server之間的連接處理； 
• 提供了一套Fluent風格的操作API； 
• 提供ZK各種應用場景的抽象封裝；

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   本文主要完成的目標是：Spring PropertyPlaceholderConfigurer配置文件加載器集成ZooKeeper來實現遠程配置讀取。

    配置管理（Configuration Management）。
    在集群服務中，可能都會遇到一個問題：那就是當需要修改配置的時候，必須要對每個實例都進行修改，這是一個很繁瑣的事情，並且易出錯。當然可以使用腳本來解決，但這不是最好的解決辦法。

OK，Let's go！

我們先看看項目結構

 

 

ZooKeeperPropertyPlaceholderConfigurer.java

繼承org.springframework.beans.factory.config.PropertyPlaceholderConfigurer，重寫processProperties(beanFactoryToProcess, props)來完成遠端配置加載的實現

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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 = "zoo.paths" ;        @Override      protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props)              throws BeansException {          super .processProperties(beanFactoryToProcess, props);                    try {              fillCustomProperties(props);                            System.out.println(props);          }          catch (Exception e) {              // Ignore              e.printStackTrace();          }      }        private void fillCustomProperties(Properties props) throws Exception {          byte [] data = getData(props);          fillProperties(props, data);      }        private void fillProperties(Properties props, byte [] data) throws UnsupportedEncodingException {          String cfg = new String(data, "UTF-8" );          if (StringUtils.isNotBlank(cfg)) {              // 完整的應該還需要處理：多條配置、value中包含=、忽略#號開頭              String[] cfgItem = StringUtils.split(cfg, "=" );              props.put(cfgItem[ 0 ], cfgItem[ 1 ]);          }      }        private byte [] getData(Properties props) throws Exception {          String path = props.getProperty(PATH);          Config config = new ZooKeeperConfig();          return config.getConfig(path);      }   }

 

 

Config.java
配置操作接口 

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

Startup.java

程序啟動入口

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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的實現

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

 

ZooKeeperFactory.java

管理ZooKeeper客戶端連接

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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 = "172.16.3.42:2181,172.16.3.65:2181,172.16.3.24:2181" ;            public static final int MAX_RETRIES = 3 ;        public static final int BASE_SLEEP_TIMEMS = 3000 ;        public static final String NAME_SPACE = "cfg" ;        public static CuratorFramework get() {          RetryPolicy retryPolicy = new ExponentialBackoffRetry(BASE_SLEEP_TIMEMS, MAX_RETRIES);          CuratorFramework client = CuratorFrameworkFactory.builder()                  .connectString(CONNECT_STRING)                  .retryPolicy(retryPolicy)                  .namespace(NAME_SPACE)                  .build();          client.start();          return client;      } }

 

applicationContext.xml

配置加載器使用我們自己創建的ZooKeeperPropertyPlaceholderConfigurer，因為它重寫了processProperties方法。這個方法里會去讀取遠程配置。

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<? xml version = "1.0" encoding = "UTF-8" ?> <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd"> < beans >            < bean class = "org.bigmouth.common.zookeeper.config.spring.ZooKeeperPropertyPlaceholderConfigurer" >          < property name = "systemPropertiesModeName" value = "SYSTEM_PROPERTIES_MODE_OVERRIDE" />          < property name = "ignoreResourceNotFound" value = "true" />          < property name = "locations" >              < list >                  < value >classpath:application.properties</ value >              </ list >          </ property >      </ bean >       </ beans >

 

application.properties

項目配置文件，里面除了配置ZooKeeper服務器地址和讀取的節點以外，其他所有的配置都應該保存在ZooKeeper中。

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1	zoo.paths=/properties

 

設置ZooKeeper數據

登錄ZooKeeper中為節點 /cfg/properties 添加一條配置項：

如圖所示：我創建了一個節點 /cfg/properties 並設置內容為：jdbc.driver=org.postgresql.Driver

運行Startup.java

OK 了，zoo.paths是本地application.properties文件中的，jdbc.driver是遠程ZooKeeper服務器中的。

 

項目中需要依賴的jar包

 

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< dependency >      < groupId >commons-lang</ groupId >      < artifactId >commons-lang</ artifactId >      < version >2.4</ version > </ dependency > < dependency >      < groupId >org.springframework</ groupId >      < artifactId >spring-core</ artifactId >      < version >3.0.3.RELEASE</ version > </ dependency > < dependency >      < groupId >org.springframework</ groupId >      < artifactId >spring-context</ artifactId >      < version >3.0.3.RELEASE</ version > </ dependency > < dependency >      < groupId >org.springframework</ groupId >      < artifactId >spring-tx</ artifactId >      < version >3.0.3.RELEASE</ version > </ dependency > < dependency >      < groupId >org.springframework</ groupId >      < artifactId >spring-context-support</ artifactId >      < version >3.0.3.RELEASE</ version > </ dependency >   <!-- ZooKeeper --> < dependency >      < groupId >org.apache.zookeeper</ groupId >      < artifactId >zookeeper</ artifactId >      < version >3.4.6</ version > </ dependency > < dependency >      < groupId >org.apache.curator</ groupId >      < artifactId >curator-framework</ artifactId >      < version >2.4.2</ version > </ dependency > < dependency >      < groupId >org.apache.curator</ groupId >      < artifactId >curator-recipes</ artifactId >      < version >2.4.2</ version > </ dependency >