Java - Using Ant to automatically generate boilerplate code

Question

Intro: I'm asking this before I try, fail and get frustrated as I have 0 experience with Apache Ant. A simple 'yes this will work' may suffice, or if it won't please tell me what will.

Situation: I'm working on a project that uses JavaFX to create a GUI. JavaFX relies on Java Bean-like objects that require a lot of boilerplate code for it's properties. For example, all functionality I want to have is a String called name with default value "Unnamed", or in a minimal Java syntax:

String name = "Unnamed";

In JavaFX the minimum amount of code increases a lot to give the same functionality (where functionality in this case means to me that I can set and get a certain variable to use in my program):

private StringProperty name = new StringProperty("Unnamed");
public final String getName() { return name.get(); }
public final void setName(String value) { name.set(value); }

Question: Can I use Ant to generate this boilerplate code?

It seems possible to make Ant scripts that function as (Java) preprocessors. For instance by using the regex replace (https://ant.apache.org/manual/Tasks/replaceregexp.html) functions. I'm thinking of lines of code similar to this in my code, which then will be auto-replaced:

<TagToSignifyReplaceableLine> StringProperty person "Unnamed"

Final remark: As I've said before I have never used Ant before, so I want to check with you if 1) this can be done and 2) if this is a good way to do it or if there are better ways.

Thanks!

Answer 1

Yes, possible. You can even implement your own Ant task, that does this job very easily.

Something like so in ant:

<taskdef name="codegen" classpath="bin/" classname="com.example.CodeGen" />

and then

<codegen className="Test.java">
   <Property name="StringProperty.name" value="Unnamed"/>
</codegen>

The CodeGen.java then like so:

public class CodeGen extends Task {
    private String className = null;
    private List properties = new ArrayList();

    public void setClassName(String className) {
        this.className = className;
    }

    /**
     * Called by ant for every <property> tag of the task.
     *  
     * @param property The property.
     */
    public void addConfiguredProperty(Property property) {
      properties.add(property);
    }

    public void execute() throws BuildException {
        // here we go!
    }

}

Answer 2

I know it can be done because my previous firm used ant to generate model objects in java.

The approach they used was to define model objects in an XML file and run an ant task to generate the pojo and dto.

I quickly googled and saw that there are tools that allow you to generate java from XML. You could probably give your schema/default values etc in XML and have an nt task to run the tool.

Answer 3

I would look at JSR-269 specifically: genftw which makes JSR-269 easier...

And yes it will work with Ant with out even having to write a plugin and will work better than a brittle RegEx.

The other option if your really adventurous is to check out XText for code generation but it is rather complicated.

Answer 4

Yes, it can be done :-)

I once wrote a webservices adapter that used a WSDL document (XML file describing a SOAP based webservice) to generate the POJO Java class that implemented the functional interface to my product. What lead me to do this was the mindlessly repetitive Java code which was necessary to talk to our proprietary system.

The technical solution used an XSLT stylesheet to transform the input XML document into an output Java text file which was subsequently compiled by ANT.

<!-- Generate the implementation classes -->
<xslt force="true" style="${resources.dir}/javaServiceStub.xsl" in="${src.dir}/DemoService.wsdl" out="${build.dir}/DemoService/src/com/myspotontheweb/DemoServiceSkeleton.java" classpathref="project.path">
    <param name="package" expression="com.myspotontheweb"/>
    ..
    ..
</xslt> 

Unfortunately XSLT is the closest thing to a templating engine supported by native ANT.

Best of luck!