WRO4J是一个很有用的API，可以最小化和压缩Web资源文件，包括CSS和JavaScript文件。WRO4J可以在建立时进行配置——使用适当的Maven插件，也可以在运行时通过过滤器进行配置。
本文讲述怎样在构建应用程序时，配置和使用WRO4J。
第一步是需要定义分组——创建和包含的资源，这通过创建wro.xml配置文件实现，此文件放入WEB-INF目录。如下：
[html]
<?xml version="1.0" encoding="UTF-8"?>
<groups xmlns="http://www.isdc.ro/wro">
<group name="javaonly-base-scripts">
<js minimize="false">/scripts/jquery-1.6.1.min.js</js>
<js minimize="false">/scripts/jqXMLUtils.pack.js</js>
<js minimize="false">/scripts/cufon/cufon-yui.js</js>
<js minimize="false">/scripts/cufon/font.js</js>
<js minimize="false">/scripts/cufon/replace.js</js>
</group>
<group name="javaonly-scripts">
<js>/scripts/scriptFile1.js</js>
<js>/scripts/scriptFile2.js</js>
</group>
<group name="javaonly-debugging">
<js minimize="false">/scripts/scriptDebug1.js</js>
<js minimize="false">/scripts/scriptDebug1.js</js>
</group>
<group name="javaonly-styles">
<css>/styles/screen/base.css</css>
<css>/styles/screen/layout.css</css>
<css>/styles/screen/content.css</css>
<css>/styles/screen/menu.css</css>
<css>/styles/screen/footer.css</css>
<css>/styles/screen/login.css</css>
<css>/styles/screen/tooltip.css</css>
<css>/styles/screen/homepage.css</css>
</group>
</groups>
</pre>
随后，我们在Maven配置文件中添加WRO4J插件。如下：
[html]
<plugin>
<groupId>ro.isdc.wro4j</groupId>
<artifactId>wro4j-maven-plugin</artifactId>
<version>${wro4j.version}</version>
<executions>
<execution>
<id>optimize-web-resources</id>
<phase>compile</phase>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
<configuration>
<ignoreMissingResources>false</ignoreMissingResources>
<jsDestinationFolder>
${project.build.directory}/${project.build.finalName}/scripts/wro/
</jsDestinationFolder>
<cssDestinationFolder>
${project.build.directory}/${project.build.finalName}/styles/wro/
</cssDestinationFolder>
<wroManagerFactory>
ro.isdc.wro.maven.plugin.manager.factory.ConfigurableWroManagerFactory
</wroManagerFactory>
</configuration>
</plugin>
最后，我们在网页上添加最小化后的资源文件，如下：
[html]
<link rel="stylesheet" type="text/css" href="/wro/javaonly-styles.css" />
<script type="text/javascript" src="/wro/javaonly-base-scripts.js"></script>
