Implement wro4j in five steps.

WRO4J (Web Resource Optimizer For Java) is an awesome open source resource optimizer. I recently implemented it in my application. So here I am providing steps I followed to implement it and issues I faced.

Tools used: Maven

1. Add maven dependency for the WRO4J in you pom.xml as follows:

	<dependency>
	<groupId>ro.isdc.wro4j</groupId>
	<artifactId>wro4j-core</artifactId>
	<version>1.5.0</version>
	<type>jar</type>
	<scope>compile</scope>
	</dependency>
	<dependency>
	<groupId>ro.isdc.wro4j</groupId>
	<artifactId>wro4j-extensions</artifactId>
	<version>1.5.0</version>
	<type>jar</type>
	<scope>compile</scope>
	</dependency>

view raw wro-dependency hosted with ❤ by GitHub

2. Add a filter in web.xml as follows:

	<filter>
	<filter-name>WebResourceOptimizer</filter-name>
	<filter-class>ro.isdc.wro.http.WroFilter</filter-class>
	</filter>
	<filter-mapping>
	<filter-name>WebResourceOptimizer</filter-name>
	<url-pattern>/resources/*</url-pattern>
	</filter-mapping>

view raw wro-filter hosted with ❤ by GitHub

3. Under WEB-INF create a folder wro.xml with content as follows:

	<?xml version="1.0" encoding="UTF-8"?>
	<groups xmlns="http://www.isdc.ro/wro"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.isdc.ro/wro wro.xsd">
	<group name="all">
	<js>/js/app.js</js>
	<js>/js/app1.js</js>
	<css>/css/main.css</css>
	<css>/css/main1.css</css>
	</group>
	</groups>

view raw wro-xml hosted with ❤ by GitHub

This will create a js and css at runtime by combining all js and css under the group all and return and all.js and all.css respectively.

4. Under same folder WEB-INF create another file wro.properties with content as follows:

debug=true
disableCache=true
gzipResources=true
jmxEnabled=false
preProcessors=semicolonAppender
postProcessors=jsMin,cssCompressor,cssMin

5. Open any new existing JSP page and add a js call as follows:

and for css add the call as:

Thats it!! Now start your server and open your page.

I faced one issue while implementing wro4j and that is due to a dependency of wro4j jars. This version of wro4j requires commons-io.2.1 but because some other dependency older version of common-io got loaded. I did not get any error but was getting empty results when calling /wro/all.js and /wro/all.css. So, be careful.

~Manish