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是否有任何使用 Apache ZooKeeper 来分发 Java 应用程序配置的有据可查的用例，尤其是 Spring 服务？

像许多云服务用户一样，我需要更改可变数量的 Java 服务的配置，最好是在运行时而不需要重新启动服务。

更新

最终我写了一些东西，将 ZooKeeper 节点作为属性文件加载，并创建一个ResourcePropertySource并将其插入到 Spring 上下文中。请注意，这不会反映上下文启动后 ZooKeeper 节点中的更改。

public class ZooKeeperPropertiesApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
    private static final Logger logger = LoggerFactory.getLogger(ZooKeeperPropertiesApplicationContextInitializer.class);

    private final CuratorFramework curator;
    private String projectName;
    private String projectVersion;

    public ZooKeeperPropertiesApplicationContextInitializer() throws IOException {
        logger.trace("Attempting to construct CuratorFramework instance");

        RetryPolicy retryPolicy = new ExponentialBackoffRetry(10, 100);
        curator = CuratorFrameworkFactory.newClient("zookeeper", retryPolicy);
        curator.start();
    }

    /**
     * Add a primary property source to the application context, populated from
     * a pre-existing ZooKeeper node.
     */
    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {
        logger.trace("Attempting to add ZooKeeper-derived properties to ApplicationContext PropertySources");

        try {
            populateProjectProperties();
            Properties properties = populatePropertiesFromZooKeeper();
            PropertiesPropertySource propertySource = new PropertiesPropertySource("zookeeper", properties);
            applicationContext.getEnvironment().getPropertySources().addFirst(propertySource);

            logger.debug("Added ZooKeeper-derived properties to ApplicationContext PropertySources");
            curator.close();
        } catch (IOException e) {
            logger.error("IO error attempting to load properties from ZooKeeper", e);
            throw new IllegalStateException("Could not load ZooKeeper configuration");
        } catch (Exception e) {
            logger.error("IO error attempting to load properties from ZooKeeper", e);
            throw new IllegalStateException("Could not load ZooKeeper configuration");
        } finally {
            if (curator != null && curator.isStarted()) {
                curator.close();
            }
        }
    }

    /**
     * Populate the Maven artifact name and version from a property file that
     * should be on the classpath, with values entered via Maven filtering.
     * 
     * There is a way of doing these with manifests, but it's a right faff when
     * creating shaded uber-jars.
     * 
     * @throws IOException
     */
    private void populateProjectProperties() throws IOException {
        logger.trace("Attempting to get project name and version from properties file");

        try {
            ResourcePropertySource projectProps = new ResourcePropertySource("project.properties");
            this.projectName = (String) projectProps.getProperty("project.name");
            this.projectVersion = (String) projectProps.getProperty("project.version");
        } catch (IOException e) {
            logger.error("IO error trying to find project name and version, in order to get properties from ZooKeeper");
        }
    }

    /**
     * Do the actual loading of properties.
     * 
     * @return
     * @throws Exception
     * @throws IOException
     */
    private Properties populatePropertiesFromZooKeeper() throws Exception, IOException {
        logger.debug("Attempting to get properties from ZooKeeper");

        try {
            byte[] bytes = curator.getData().forPath("/distributed-config/" + projectName + "/" + projectVersion);
            InputStream in = new ByteArrayInputStream(bytes);
            Properties properties = new Properties();
            properties.load(in);
            return properties;
        } catch (NoNodeException e) {
            logger.error("Could not load application configuration from ZooKeeper as no node existed for project [{}]:[{}]", projectName, projectVersion);
            throw e;
        }

    }

}
4

6 回答 6

6

您应该考虑 Spring Cloud Config：

http://projects.spring.io/spring-cloud/

Spring Cloud Config 由 git 存储库支持的集中式外部配置管理。配置资源直接映射到 Spring Environment，但如果需要，可以由非 Spring 应用程序使用。

此处提供源代码：

https://github.com/spring-cloud/spring-cloud-config

此处的示例应用程序：

https://github.com/spring-cloud/spring-cloud-config/blob/master/spring-cloud-config-sample/src/main/java/sample/Application.java

于 2014-09-14T17:56:45.440 回答
2

我创建了一套spring bean集成zookeeper和springframework为propertyplaceholderconfigurer，在github：https ://github.com/james-wu-shanghai/spring-zookeeper.git 你可以看看。

于 2013-05-11T12:58:02.800 回答
1

不是特别是spring，但对于java来说，有一个分布式OSGI标准的CXF实现，它使用ZooKeeper作为发现服务器将更新的包推送到容器：http ://cxf.apache.org/dosgi-discovery.html .

于 2012-03-30T14:59:03.967 回答
1

Zookeeper 可以很好地利用 Curator API 进行更高的抽象，用于分布式应用程序中的配置管理。要开始，只需按照这两个步骤。

STEP 1 : Start zookeper server and then start zookeeper cli and create some znodes. Znodes are nothing but UNIX like files which contain values, and name of files depict property name.
To create/fetch/update properties use these commands on zookeeper cli.

create /system/dev/example/port 9091
get /system/dev/example/port
set /system/dev/example/port 9092

要在 java 程序中获取这些属性，请参阅此代码片段。

import java.util.HashMap;
import java.util.Map;

import org.apache.curator.framework.CuratorFramework; 
import org.apache.curator.framework.CuratorFrameworkFactory; 
import org.apache.curator.retry.ExponentialBackoffRetry;
public class App 
{
    public static void main( String[] args ) throws Exception
    {
         final String ZK = "localhost:2181"; 

         final Map<String, String> data = new HashMap<String, String>();         
         CuratorFramework client = CuratorFrameworkFactory.newClient(ZK, new ExponentialBackoffRetry(100, 3)); 
         client.start();
         System.out.println(new String(client.getData().forPath("/system/dev/example/port")));
       }  
}
于 2017-01-11T09:33:50.197 回答
0

上周我参加了 James Strachen 的一次 Apache Camel 演讲，他提到在他们的云端基于 Java 的服务器上使用 ZooKeeper作为配置信息的来源。

我看过 Adrian Colyer（SpringSource 的 CTO）关于 Spring 中运行时配置更改的演讲，但是 Spring 今天是否支持这一点？

在我看来，如果你是从一个典型的架构 Spring 应用程序开始的，我认为你在它之上改进动态配置更改并不是一件容易的事。

于 2012-03-30T11:21:31.810 回答
0

在找到使用 aFactoryBean填充常规的建议后，PropertyPlaceholderConfigurer我构建了这个：

package fms;

import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.config.AbstractFactoryBean;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.Properties;

public class ZkPropertiesFactoryBean extends AbstractFactoryBean<Properties> implements Watcher {
    private Logger LOGGER = LoggerFactory.getLogger(ZkPropertiesFactoryBean.class);
    private String zkConnect;
    private String path;
    private int timeout = 1000;

    @Override protected Properties createInstance() throws Exception {
        long start = System.currentTimeMillis();
        Properties p = new Properties();
        p.load(new ByteArrayInputStream(loadFromZk()));
        double duration = (System.currentTimeMillis() - start)/1000d;
        LOGGER.info(String.format("Loaded %d properties from %s:%s in %2.3f sec", p.size(), zkConnect, path, duration));
        return p;
    }

    @Override public Class<Properties> getObjectType() {
        return Properties.class;
    }

    private byte[] loadFromZk() throws IOException, KeeperException, InterruptedException {Stat stat = new Stat();
        ZooKeeper zk = new ZooKeeper(zkConnect, timeout, this);
        return zk.getData(path, false, stat);
    }

    @Override public void process(WatchedEvent event) {}

    public void setPath(String path) {this.path = path;}

    public void setZkConnect(String zkConnect) {this.zkConnect = zkConnect;}
}

在spring-config.xml你创建bean如下：

<bean id="zkProperties" class="fms.ZkPropertiesFactoryBean" p:zkConnect="localhost:2181" p:path="/app/zk-properties"/>
<context:property-placeholder properties-ref="zkProperties"/>
于 2013-11-15T20:17:53.230 回答