让我们看一下Spring中的Dynamic Property Management。

二手技术：

JDK 1.6.0_31
春天3.1.1
石英1.8.5 Maven的3.0.2

步骤1：建立已完成的专案

如下创建一个Maven项目。 （可以使用Maven或IDE插件来创建它）。

步骤2：图书馆

Spring依赖项已添加到Maven的pom.xml中。

<properties><spring.version>3.1.1.RELEASE</spring.version></properties><dependencies><!-- Spring 3 dependencies --><dependency><groupId>org.springframework</groupId><artifactId>spring-core</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context-support</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-tx</artifactId><version>${spring.version}</version></dependency><!-- Quartz dependency --><dependency><groupId>org.quartz-scheduler</groupId><artifactId>quartz</artifactId><version>1.8.5</version></dependency><!-- Log4j dependency --><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.16</version></dependency></dependencies>

步骤3：创建DynamicPropertiesFile.properties

DynamicPropertiesFile涵盖了应用程序的动态属性。

# This property defines message content
# Possible values = Text. Default value : Welcome
Message_Content = Welcome Visitor# This property defines minimum visitor count
# Possible values = positive integer. Default value : 1
Minimum_Visitor_Count = 1# This property defines maximum visitor count
# Possible values = positive integer. Default value : 10
Maximum_Visitor_Count = 10

步骤4：创建applicationContext.xml

应用程序上下文的创建如下：

<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-3.0.xsd"><!-- Beans Declaration --><!-- Core Dynamic Properties Bean Declaration --><bean id="CoreDynamicPropertiesBean" class="org.springframework.beans.factory.config.PropertiesFactoryBean" scope="prototype"><property name="location" value="classpath:DynamicPropertiesFile.properties" /></bean><!-- Dynamic Properties Map Declaration --><bean id="DynamicPropertiesMap" class="java.util.HashMap"/><!-- Dynamic Properties File Reader Task Declaration --><bean id="DynamicPropertiesFileReaderTask" class="com.otv.dynamic.properties.task.DynamicPropertiesFileReaderTask"><property name="dynamicPropertiesMap"   ref="DynamicPropertiesMap"/></bean><!-- End of Beans Declaration --><!-- Scheduler Configuration --><!-- Job Detail--><bean id="DynamicPropertiesFileReaderTaskJobDetail" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean"><property name="targetObject" ref="DynamicPropertiesFileReaderTask" /><property name="targetMethod" value="start" /></bean><!-- Simple Trigger --><bean id="DynamicPropertiesFileReaderTaskTrigger" class="org.springframework.scheduling.quartz.SimpleTriggerBean"><property name="jobDetail" ref="DynamicPropertiesFileReaderTaskJobDetail" /><property name="repeatInterval" value="60000" /><property name="startDelay" value="0" /></bean><bean class="org.springframework.scheduling.quartz.SchedulerFactoryBean"><property name="jobDetails"><list><ref bean="DynamicPropertiesFileReaderTaskJobDetail" /></list></property><property name="triggers"><list><ref bean="DynamicPropertiesFileReaderTaskTrigger" /></list></property></bean><!-- End of Scheduler Configuration -->
</beans>

步骤5：建立SystemConstants类别

创建一个新的SystemConstants类。 此类涵盖所有系统常数。

package com.otv.common;/*** System Constants** @author  onlinetechvision.com* @since   26 May 2012* @version 1.0.0**/
public class SystemConstants {//Names of Dynamic Properties...public static final String DYNAMIC_PROPERTY_MESSAGE_CONTENT = "Message_Content";public static final String DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT = "Minimum_Visitor_Count";public static final String DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT = "Maximum_Visitor_Count";//Default Values of Dynamic Properties...public static final String DYNAMIC_PROPERTY_MESSAGE_CONTENT_DEFAULT_VALUE       = "Welcome";public static final String DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT_DEFAULT_VALUE = "1";public static final String DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT_DEFAULT_VALUE = "10";public static final String BEAN_NAME_CORE_DYNAMIC_PROPERTIES_BEAN = "CoreDynamicPropertiesBean";public static final String APPLICATION_CONTEXT_FILE_NAME = "applicationContext.xml";
}

步骤6：创建DynamicPropertiesFileReaderTask类

DynamicPropertiesFileReaderTask类已创建。 此类由Quartz管理。 它通过每分钟调用“ start”方法，通过DynamicPropertiesFile读取所有动态属性。 可以通过applicationContext.xml更改阅读时间。

请注意，默认情况下coreDynamicPropertiesBean的作用域为Singleton 。 它必须在运行时返回动态属性的新值，因此应将其范围设置为Prototype 。 否则，将无法接收新值。

package com.otv.dynamic.properties.task;import java.util.HashMap;
import java.util.Properties;import org.apache.log4j.Logger;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;import com.otv.common.SystemConstants;/*** Dynamic Properties File Reader Task** @author  onlinetechvision.com* @since   26 May 2012* @version 1.0.0**/
public class DynamicPropertiesFileReaderTask implements BeanFactoryAware {private static Logger logger = Logger.getLogger(DynamicPropertiesFileReaderTask.class);private Properties coreDynamicPropertiesBean;private HashMap<String, String> dynamicPropertiesMap;private BeanFactory beanFactory;/*** Starts reading the dynamic properties**/public void start() {setCoreDynamicPropertiesBean(createCoreDynamicPropertiesBeanInstance());logger.info("**** Dynamic Properties File Reader Task is being started... ****");readConfiguration();logger.info("**** Dynamic Properties File Reader Task is stopped... ****");}/*** Reads all the dynamic properties**/private void readConfiguration() {readMessageContent();readMinimumVisitorCount();readMaximumVisitorCount();}/*** Reads Message_Content dynamic property**/private void readMessageContent() {String messageContent = getCoreDynamicPropertiesBean().getProperty(SystemConstants.DYNAMIC_PROPERTY_MESSAGE_CONTENT,SystemConstants.DYNAMIC_PROPERTY_MESSAGE_CONTENT_DEFAULT_VALUE);if (messageContent.equals("")){getDynamicPropertiesMap().put(SystemConstants.DYNAMIC_PROPERTY_MESSAGE_CONTENT,SystemConstants.DYNAMIC_PROPERTY_MESSAGE_CONTENT_DEFAULT_VALUE);logger.error(SystemConstants.DYNAMIC_PROPERTY_MESSAGE_CONTENT +" value is not found so its default value is set. Default value : " +SystemConstants.DYNAMIC_PROPERTY_MESSAGE_CONTENT_DEFAULT_VALUE);} else {messageContent = messageContent.trim();getDynamicPropertiesMap().put(SystemConstants.DYNAMIC_PROPERTY_MESSAGE_CONTENT, messageContent);logger.info(SystemConstants.DYNAMIC_PROPERTY_MESSAGE_CONTENT + " : " +getDynamicPropertiesMap().get(SystemConstants.DYNAMIC_PROPERTY_MESSAGE_CONTENT));}}/*** Reads Minimum_Visitor_Count dynamic property**/private void readMinimumVisitorCount() {String minimumVisitorCount = getCoreDynamicPropertiesBean().getProperty(SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT,SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT_DEFAULT_VALUE).trim();try {if (Integer.parseInt(minimumVisitorCount) > 0){getDynamicPropertiesMap().put(SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT, minimumVisitorCount);logger.info(SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT + " : " +getDynamicPropertiesMap().get(SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT));} else {getDynamicPropertiesMap().put(SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT,SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT_DEFAULT_VALUE);logger.error("Invalid "+SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT +" value encountered. Must be greater than 0. Its default value is set. Default value : "+ SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT_DEFAULT_VALUE);}} catch (NumberFormatException nfe) {logger.error("Invalid "+SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT +" value encountered. Must be numeric!", nfe);logger.warn(SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT +" default value is set. Default value : " +SystemConstants.DYNAMIC_PROPERTY_MINIMUM_VISITOR_COUNT_DEFAULT_VALUE);}}/*** Reads Maximum_Visitor_Count dynamic property**/private void readMaximumVisitorCount() {String maximumVisitorCount = getCoreDynamicPropertiesBean().getProperty(SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT,SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT_DEFAULT_VALUE).trim();try {if (Integer.parseInt(maximumVisitorCount) > 0){getDynamicPropertiesMap().put(SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT, maximumVisitorCount);logger.info(SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT + " : " +getDynamicPropertiesMap().get(SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT));} else {getDynamicPropertiesMap().put(SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT,SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT_DEFAULT_VALUE);logger.error("Invalid "+SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT +" value encountered. Must be greater than 0. Its default value is set. Default value : " +SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT_DEFAULT_VALUE);}} catch (NumberFormatException nfe) {logger.error("Invalid "+SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT +" value encountered. Must be numeric!", nfe);logger.warn(SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT +" default value is set. Default value : " +SystemConstants.DYNAMIC_PROPERTY_MAXIMUM_VISITOR_COUNT_DEFAULT_VALUE);}}/*** Gets CoreDynamicPropertiesBean** @return Properties coreDynamicPropertiesBean*/public Properties getCoreDynamicPropertiesBean() {return coreDynamicPropertiesBean;}/*** Sets CoreDynamicPropertiesBean** @param Properties coreDynamicPropertiesBean*/public void setCoreDynamicPropertiesBean(Properties coreDynamicPropertiesBean) {this.coreDynamicPropertiesBean = coreDynamicPropertiesBean;}/*** Gets DynamicPropertiesMap** @return HashMap dynamicPropertiesMap*/public HashMap<String, String> getDynamicPropertiesMap() {return dynamicPropertiesMap;}/*** Sets DynamicPropertiesMap** @param HashMap dynamicPropertiesMap*/public void setDynamicPropertiesMap(HashMap<String, String> dynamicPropertiesMap) {this.dynamicPropertiesMap = dynamicPropertiesMap;}/*** Gets a new instance of CoreDynamicPropertiesBean** @return Properties CoreDynamicPropertiesBean*/public Properties createCoreDynamicPropertiesBeanInstance() {return  (Properties) this.beanFactory.getBean(SystemConstants.BEAN_NAME_CORE_DYNAMIC_PROPERTIES_BEAN);}/*** Sets BeanFactory** @param BeanFactory beanFactory*/public void setBeanFactory(BeanFactory beanFactory) throws BeansException {this.beanFactory = beanFactory;}}

步骤7：创建应用程序类

应用程序类启动项目。

package com.otv.starter;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.otv.common.SystemConstants;/*** Application Starter Class** @author  onlinetechvision.com* @since   26 May 2012* @version 1.0.0**/
public class Application {/*** Main method of the Application**/public static void main(String[] args) {new ClassPathXmlApplicationContext(SystemConstants.APPLICATION_CONTEXT_FILE_NAME);}
}

第8步：运行项目

如果运行应用程序类，则显示以下控制台日志：

26.05.2012 17:25:09  INFO (DefaultLifecycleProcessor.java:334) - Starting beans in phase 2147483647
26.05.2012 17:25:09  INFO (SchedulerFactoryBean.java:648) - Starting Quartz Scheduler now
26.05.2012 17:25:09  INFO (PropertiesLoaderSupport.java:177) - Loading properties file from class path resource [DynamicPropertiesFile.properties]
26.05.2012 17:25:09  INFO (DynamicPropertiesFileReaderTask.java:36) - **** Dynamic Properties File Reader Task is being started... ****
26.05.2012 17:25:09  INFO (DynamicPropertiesFileReaderTask.java:63) - Message_Content : Welcome Visitor
26.05.2012 17:25:09  INFO (DynamicPropertiesFileReaderTask.java:76) - Minimum_Visitor_Count : 1
26.05.2012 17:25:09  INFO (DynamicPropertiesFileReaderTask.java:96) - Maximum_Visitor_Count : 10
26.05.2012 17:25:09  INFO (DynamicPropertiesFileReaderTask.java:38) - **** Dynamic Properties File Reader Task is stopped... ****26.05.2012 17:26:09  INFO (PropertiesLoaderSupport.java:177) - Loading properties file from class path resource [DynamicPropertiesFile.properties]
26.05.2012 17:26:09  INFO (DynamicPropertiesFileReaderTask.java:36) - **** Dynamic Properties File Reader Task is being started... ****
26.05.2012 17:26:09  INFO (DynamicPropertiesFileReaderTask.java:63) - Message_Content : Welcome Visitor, Bruce!
26.05.2012 17:26:09  INFO (DynamicPropertiesFileReaderTask.java:76) - Minimum_Visitor_Count : 2
26.05.2012 17:26:09  INFO (DynamicPropertiesFileReaderTask.java:96) - Maximum_Visitor_Count : 20
26.05.2012 17:26:09  INFO (DynamicPropertiesFileReaderTask.java:38) - **** Dynamic Properties File Reader Task is stopped... ****

步骤9：下载

OTV_SpringDynamicPropertyManagement

参考资料：

Spring Framework参考3.x

参考： Online Technology Vision博客中的JCG合作伙伴 Eren Avsarogullari提供的Spring动态物业管理 。