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

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

OK，Let's go！

我们先看看项目结构

ZooKeeperPropertyPlaceholderConfigurer.java

继承org.springframework.beans.factory.config.PropertyPlaceholderConfigurer，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 = "zoo.paths";@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 = 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)) {// 完整的应该还需要处理：多条配置、value中包含=、忽略#号开头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

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

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");}}

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 {@Overridepublic 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);}}

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 = "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

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

<?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

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

设置ZooKeeper数据

登录ZooKeeper中为节点 /cfg/properties 添加一条配置项：

如图所示：我创建了一个节点 /cfg/properties 并设置内容为：jdbc.driver=org.postgresql.Driver

运行Startup.java

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

项目中需要依赖的jar包

<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>

相关资料：

Apache ZooKeeper

博主，问个zk值被刷了的问题。

假设，我们现在配置的数据，都是从zk中获取的，但是某个值被刷新了，我们有个watch监控到了，但是这个值怎么刷入到内存中，或者说重新注册那个bean？

有没有这方面的解决思路，我有点迷惑