commons-configuration是Apache开源组织提供的用于操作配置文件的工具包。配置参数的来源可以是：Properties files、XML documents、Windows INI files、Property list files (plist)、JNDI、JDBC Datasource、System properties、Applet parameters和Servlet parameters。  下面为大家介绍几种常用的配置方法。

Properties files

首先我们创建一个属性文件，内容如下：

userId=jianggujin userName=\u848B\u56FA\u91D1 age=22 descript=${userId} ${userName} ${age} 1234 1234

示例代码：

package com.gujin.configuration; import java.net.URL; import java.util.Iterator; import org.apache.commons.configuration.PropertiesConfiguration; import org.junit.Test; public class ConfigurationTest { @Test public void testProperties() throws Exception { Class<?> clazz = getClass(); URL url = clazz.getResource("configuration.properties"); PropertiesConfiguration configuration = new PropertiesConfiguration(url); // 遍历配置的键 for (Iterator<String> iterator = configuration.getKeys(); iterator .hasNext();) { System.out.println(iterator.next()); } System.out.println(configuration.getString("userId")); System.out.println(configuration.getInt("age")); System.out.println(configuration.getString("descript")); } } 123456789101112131415161718192021222324252627 123456789101112131415161718192021222324252627

运行结果：

userId userName age descript jianggujin 22 jianggujin 蒋固金 22 1234567 1234567

XML documents

同样的，我们先来创建一个xml文件

<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> <display-name>Servlet</display-name> <servlet> <servlet-name>test</servlet-name> <servlet-class>com.gujin.servlet.UrlPatternTest</servlet-class> </servlet> <servlet-mapping> <servlet-name>test</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <filter> <filter-name>cd</filter-name> <filter-class>com.gujin.filter.CrossDomainFilter</filter-class> </filter> <filter-mapping> <filter-name>cd</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app> 1234567891011121314151617181920 1234567891011121314151617181920

很熟悉有木有，这就是Java WEB项目的配置文件。

示例代码：

package com.gujin.configuration; import java.net.URL; import java.util.Iterator; import java.util.List; import org.apache.commons.configuration.HierarchicalConfiguration; import org.apache.commons.configuration.PropertiesConfiguration; import org.apache.commons.configuration.XMLConfiguration; import org.junit.Test; public class ConfigurationTest { @Test public void testXML() throws Exception { Class<?> clazz = getClass(); URL url = clazz.getResource("configuration.xml"); XMLConfiguration configuration = new XMLConfiguration(url); System.out.println("RootElementName:" + configuration.getRootElementName()); System.out.println("id:" + configuration.getProperty("[@id]")); System.out.println("version:" + configuration.getProperty("[@version]")); System.out.println("xmlns:xsi:" + configuration.getProperty("[@xmlns:xsi]")); System.out.println("xmlns:" + configuration.getProperty("[@xmlns]")); System.out.println("xsi:schemaLocation:" + configuration.getProperty("[@xsi:schemaLocation]")); System.out.println("display-name:" + configuration.getProperty("display-name")); // 解析servlet System.out.println("-----------------parse servlet"); List<HierarchicalConfiguration> servlets = configuration .configurationsAt("servlet"); for (HierarchicalConfiguration servlet : servlets) { System.out .println("servlet-name:" + servlet.getString("servlet-name")); System.out.println("servlet-class:" + servlet.getString("servlet-class")); } // 解析servlet mapping System.out.println("-----------------parse servlet mapping"); List<HierarchicalConfiguration> servletMappings = configuration .configurationsAt("servlet-mapping"); for (HierarchicalConfiguration servletMapping : servletMappings) { System.out.println("servlet-name:" + servletMapping.getString("servlet-name")); System.out.println("url-pattern:" + servletMapping.getString("url-pattern")); } } } 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556

运行结果：

RootElementName:web-app id:WebApp_ID version:2.5 xmlns:xsi:http://www.w3.org/2001/XMLSchema-instance xmlns:http://java.sun.com/xml/ns/javaee xsi:schemaLocation:http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd display-name:Servlet -----------------parse servlet servlet-name:test servlet-class:com.gujin.servlet.UrlPatternTest -----------------parse servlet mapping servlet-name:test url-pattern:/ 12345678910111213 12345678910111213