Can I convert an artifactId to a classname prefix

问题:

I'm creating a maven archetype and in the projects generated a want a class that is named after the artifact id of the generated project.

The artifact id will be formatted like: the-project-name and the class should be named TheProjectNameMain.

I've tried to do this in my archetype-metadata.xml but I can't get it right.

<archetype-descriptor>
    <requiredProperties>
        <requiredProperty key="classNamePrefix">
            <defaultValue>${WordUtils.capitalize(artifactId.replaceAll("-", " ")).replaceAll(" ", "")}</defaultValue>
        </requiredProperty>        
    </requiredProperties>
</archetype-descriptor>

As you can see i tried to use WordUtils (from apache-commons) but i'm guessing this is not available because i'm getting an error. Error merging velocity templates:.... . I also tried different combinations of .replaceAll but i couldn't get the right format.

Does anyone know of a way to go from a-hypenated-string to a CamelCaseClassName in this case?

回答1:

There is no access to arbitrary java classes from Velocity, but you can call methods of existing objects. In the context of Maven archetype you can use methods from java.lang.String and a Velocity loop to get the job done.

#macro( ccase $str )
#foreach( $word in $str.split('-') )$word.substring(0,1).toUpperCase()$word.substring(1)#end
#end
#set( $classNamePrefix = "#ccase( $artifactId )" )

public class ${classNamePrefix}Application {
    // ...
}

If you are using a fileSet tag, add filtered="true" property to make sure source files are processed with Velocity.

See also:

• http://velocity.apache.org/engine/1.4/user-guide.html#Loops

There's updated documentation for version 2.0: http://velocity.apache.org/engine/2.0/user-guide.html#loops

回答2:

I wanted to be able to do this in file names, so I came up with a hack for a camel case artifactId property:

<requiredProperty key="artifactIdCamelCase">
  <defaultValue>${artifactId.replaceAll("^a|-a", "A").replaceAll("^b|-b", "B").replaceAll("^c|-c", "C").replaceAll("^d|-d", "D").replaceAll("^e|-e", "E").replaceAll("^f|-f", "F").replaceAll("^g|-g", "G").replaceAll("^h|-h", "H").replaceAll("^i|-i", "I").replaceAll("^j|-j", "J").replaceAll("^k|-k", "K").replaceAll("^l|-l", "L").replaceAll("^m|-m", "M").replaceAll("^n|-n", "N").replaceAll("^o|-o", "O").replaceAll("^p|-p", "P").replaceAll("^q|-q", "Q").replaceAll("^r|-r", "R").replaceAll("^s|-s", "S").replaceAll("^t|-t", "T").replaceAll("^u|-u", "U").replaceAll("^v|-v", "V").replaceAll("^w|-w", "W").replaceAll("^x|-x", "X").replaceAll("^y|-y", "Y").replaceAll("^z|-z", "Z")}</defaultValue>
</requiredProperty>

That will convert any artifactId that follows the naming convention of hyphenated, lower case a-z to camel case. From some limited testing, the format is fragile so small edits such as line breaks and regex additions may stop Velocity from replacing the property.

Should work on Maven versions after 2.1 (when this bug was fixed). My version:

> mvn -v
Apache Maven 3.2.5 (12a6b3acb947671f09b81f49094c53f426d8cea1; 2014-12-14T11:29:23-06:00)

---

Also here is a sometimes-useful, unhyphenated version of artifactId:

<requiredProperty key="artifactIdUnhyphenated">
  <defaultValue>${artifactId.replace("-","")}</defaultValue>
</requiredProperty>

回答3:

To variabilize your file name, you can set a requiredProperty and use other properties to build it

<requiredProperty key="routeBuilderFileName"><defaultValue>RouteBuilder${flowName.toUpperCase()}${flowWay.substring(0,1).toUpperCase()}${flowWay.substring(1)}</defaultValue></requiredProperty>

Then name the template file : __routeBuilderFileName__.java