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:

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

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

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