参考:http://seraph115.iteye.com/blog/435165
Spring中PropertyPlaceholderConfigurer这个类,它是用来解析Java Properties属性文件值,并提供在spring配置期间替换使用属性值。接下来让我们逐渐的深入其配置。
基本的使用方法是:
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- <bean id="propertyConfigurerForAnalysis"
- class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
- <property name="location">
- <value>classpath:/spring/include/dbQuery.properties</value>
- </property>
- </bean>
其中classpath是引用src目录下的文件写法。
当存在多个Properties文件时,配置就需使用locations了:(2)
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- <bean id="propertyConfigurer"
- class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
- <property name="locations">
- <list>
- <value>classpath:/spring/include/jdbc-parms.properties</value>
- <value>classpath:/spring/include/base-config.properties</value>
- </list>
- </property>
- </bean>
接下来我们要使用多个PropertyPlaceholderConfigurer来分散配置,达到整合多工程下的多个分散的Properties文件,其配置如下:(3)
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- <bean id="propertyConfigurerForProject1"
- class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
- <property name="order" value="1" />
- <property name="ignoreUnresolvablePlaceholders" value="true" />
- <property name="locations">
- <list>
- <value>classpath:/spring/include/dbQuery.properties</value>
- </list>
- </property>
- </bean>
- <bean id="propertyConfigurerForProject2"
- class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
- <property name="order" value="2" />
- <property name="ignoreUnresolvablePlaceholders" value="true" />
- <property name="locations">
- <list>
- <value>classpath:/spring/include/jdbc-parms.properties</value>
- <value>classpath:/spring/include/base-config.properties</value>
- </list>
- </property>
- </bean>
其中order属性代表其加载的顺序,如果没有设置就按照加载xml文件时的顺序,而ignoreUnresolvablePlaceholders为是否忽略不可解析的Placeholder,如果配置了多个PropertyPlaceholderConfigurer,则该属性必须设置且为true,否则propertyConfigurerForProject2的properties文件不会被加载.
至此你已经了解到了如何使用PropertyPlaceholderConfigurer,如何使用多个Properties文件,以及如何配置多个PropertyPlaceholderConfigurer来分解工程中分散的Properties文件。至于PropertyPlaceholderConfigurer还有更多的扩展应用,如属性文件加密解密等方法将在之后的博文中续写。
注意事项:
(1)如果上面的dbQuery.properties与jdbc-parms.properties文件中有相同的参数配置名称,dbQuery.properties中配置的参数值不会被后面的覆盖;
(2)如果jdbc-parms.properties,base-config.properties彼此有相同参数名配置,jdbc-parms.properties中的配置的值会被覆盖;
自定义扩展PropertyPlaceholderConfigurer实现
例如:配置文件的路径,需要动态确定的,就需要自己扩展PropertyPlaceholderConfigurer的实现,自己获取文件路径,load properties文件,然后将load后的properties加入PropertyPlaceholderConfigurer
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- package com.common.spring.ext;
- import java.util.Properties;
- import java.util.Set;
- import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
- import com.common.exception.ApplicationException;
- import com.common.util.GlobalProperties;
- import com.common.util.PropertiesUtil;
- public class GollfPropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {
- public void setGollfPropFiles(Set<String> gollfPropFiles) {
- String propPath = GlobalProperties.getProperty(GlobalProperties.PROPERTIES_FOLDER_PATH); //通过其他配置获取路径
- String fileSeparator = System.getProperty("file.separator");
- Properties properties = new Properties();
- for (String gollfPropFile : gollfPropFiles) {
- String nodeName = System.getProperty("weblogic.Name");
- gollfPropFile = gollfPropFile.replaceAll("\\[NODE_NAME\\]", nodeName); //NODE_NAME 是根据不同weblogic server确定
- String file = propPath + fileSeparator + gollfPropFile;
- try {
- logger.info("Loading properites file from " + file);
- Properties prop = PropertiesUtil.loadProperties(file); //返回properties文件
- logger.debug("Properties -> " + prop);
- if(prop != null) {
- properties.putAll(prop);
- }
- } catch (Exception e) {
- logger.fatal(new ApplicationException("Properties file " + gollfPropFile +
- " cannot be found. All related functionalities may be unavailable", e, true));
- }
- }
- this.setProperties(properties); //关键方法,调用的PropertyPlaceholderConfigurer中的方法,
- //通过这个方法将自定义加载的properties文件加入spring中
- }
- }
xml配置
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- <bean id="auditJmsProperties"
- class="com.common.spring.ext.GollfPropertyPlaceholderConfigurer">
- <property name="gollfPropFiles">
- <set>
- <value>[NODE_NAME]_jms.properties</value>
- </set>
- </property>
- </bean>
PropertyPlaceholderConfigurer中加载properties文件时,实际调用的:org.springframework.core.io.support.PropertiesLoaderSupport中的mergeProperties
Spring源码
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- protected Properties mergeProperties() throws IOException {
- Properties result = new Properties();
- if (this.localOverride) {
- // Load properties from file upfront, to let local properties override.
- loadProperties(result);
- }
- if (this.localProperties != null) {
- for (Properties localProp : this.localProperties) {
- //将用户自定义加载的属性值,与spring加载的合并
- CollectionUtils.mergePropertiesIntoMap(localProp, result);
- }
- }
- if (!this.localOverride) {
- // Load properties from file afterwards, to let those properties override.
- loadProperties(result);
- }
- return result;
- }
将多个properties文件中的配置加载以后合并成一个Properties对象返回.
上面的this.setProperties(properties)方法,就是设置localProperties的引用,localProperties不为空的话,将用户自定义加载的properties属性合并到Spring加载的result Properties对象中
localOverride参数:为true的话,表示用户自定义加载的属性值覆盖spring系统加载的,如果同名的话.
自定义使用注意:用户自定义方法的调用务必在spring 初始化调用PropertyPlaceholderConfigurer的mergeProperties()方法之前调用,否则配置文件就没有合并.一般就set值的时候调用.