Spring MVC Zookeeper 统一配置管理

继吉

　　资料摘自：http://www.big-mouth.cn/blog/65.html
　　背景说明：在基于Spring MVC框架的开发的项目中，由于存在大量的数据库配置、第三方配置信息、环境路径配置信息，一直使用Maven的profile方式来对各种配置信息进行管理(该方式不多做介绍)，在维护方面成本较高。针对以上情况，准备借助zookeeper来对不同配置信息进行统一管理(当然其他缓存工具也可以，原理相同)。
　　第一步：安装zookeeper服务端(资料较多，这里不多解释)
　　第二步：在java中引入apache.zookeeper.ZooKeeper第三方API。

<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.4.6</version>
</dependency>
　　第三步：编写zookeeper工具类(简单工具类)

package cn.com.timerbin.zookeeper.demo;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.List;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooKeeper;
public class ZookeeperClientUtil {
private ZooKeeper zk;
//zookeeper地址
private String servers;
//链接超时时间
private int sessionTimeout = 40000;
private String mainPath;
public ZooKeeper getAliveZk() {
ZooKeeper aliveZk = zk;
if (aliveZk != null && aliveZk.getState().isAlive()) {
return aliveZk;
} else {
zkReconnect();
return zk;
}
}
public synchronized void zkReconnect() {
close();
try {
connect();
} catch (IOException e) {
}
}
public synchronized void close() {
if (zk != null) {
try {
zk.close();
} catch (InterruptedException e) {
}
zk = null;
}
}
private synchronized void connect() throws IOException {
if (zk == null  && !StringUtils.isBlank(servers))
zk = new ZooKeeper(servers, sessionTimeout, null);
}
public String getData(String path) {
String result = null;
try {
byte [] data = getAliveZk().getData(path, Boolean.TRUE,null);
if(null != data){
result = new String(data, "UTF-8");
}
} catch (KeeperException e) {
} catch (InterruptedException e) {
} catch (UnsupportedEncodingException e) {
}
return result ;
}
public List<String> getChildren(){
List<String> data = null;
try {
data = getAliveZk().getChildren(mainPath, Boolean.TRUE);
} catch (KeeperException e) {
} catch (InterruptedException e) {
}
return data;
}
public void setSessionTimeout(int sessionTimeout) {
this.sessionTimeout = sessionTimeout;
}
public String getMainPath() {
return mainPath;
}
public void setMainPath(String mainPath) {
this.mainPath = mainPath;
}
public void setServers(String servers) {
this.servers = servers;
}
}

　　注：此工具类仅供参考，请注意其中 zk.getChildren()/zk.getData()方法中的Watcher参数使用。
　　第四步：Spring配置文件中对ZookeeperClientUtil 配置定义

<bean id="zookeeperClient" class="cn.com.timerbin.zookeeper.demo.ZookeeperClientUtil">
<property name="servers" value="127.0.0.1:2181" />
<property name="mainPath" value="/configuration/allconfig" />
</bean>
　　第五步：重写配置文件配置器

package cn.com.timerbin.zookeeper.demo;
import java.util.List;
import java.util.Properties;
import org.springframework.beans.BeansException;
import org.springframework.beans.PropertyValue;
import org.springframework.beans.factory.BeanInitializationException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.PropertyOverrideConfigurer;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import cn.com.timerbin.zookeeper.demo.ZookeeperClientUtil;
public class ZooKeeperPropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {
private ZookeeperClientUtil configurationClient;
public void setConfigurationClient(ZookeeperClientUtil configurationClient) {
this.configurationClient = configurationClient;
}
@Override
protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props)
throws BeansException {
try {
List<String> list= configurationClient.getChildren();
for(String key:list){
String value = configurationClient.getData(configurationClient.getMainPath()+"/"+key);
if(!StringUtils.isBlank(value)){
props.put(key,value);
}
}
} catch (Exception e) {
}
super.processProperties(beanFactoryToProcess, props);
}
}
　　第六步：在Spring配置文件中对ZooKeeperPropertyPlaceholderConfigurer进行配置定义

<bean id="zooKeeperPropertyPlaceholderConfigurer" class="cn.com.timerbin.zookeeper.demo.ZooKeeperPropertyPlaceholderConfigurer">
<property name="configurationClient" ref="zookeeperClient"></property>
<property name="order" value="1" />
<property name="ignoreUnresolvablePlaceholders" value="true" />
</bean>
　　其中：ignoreUnresolvablePlaceholders:配置即当此PropertyPlaceholder不可解析时是否忽略。
　　注：如果在第六步中配置中配置了如下信息时

<property name="locations">
<list>
<value>classpath:application.properties</value>
</list>
</property>
　　此时在第五部中的processProperties方法的props中就已经包含了application.properties配置中的所有配置信息，关于工具类（ZookeeperClientUtil）中的一些配置参数的设置也可以考虑基于props来进行定义设置！