How to add custom code to JAXWS generated source

Question

Is it possible to customise the code for a JAXWS class. What I want to do is add some helper methods to the generated class to help extract information from it. I know I can subclass the generated source but this means I have to cast it everywhere I want the info.

Is it possible to have jaxws (or another tool) merge together the generated source code from the WSDL with some custom code containing my methods? (In C# I could do this with a partial class but java doesn't appear to have an equivalent)...

Answer 1

One approach to achieve this would be to introduce those helper methods via aspects. AspectJ would be a potential candidate for this, or if you're using Spring, then Spring AOP could also do the job.

So using AspectJ, you'd leverage the feature called "inter-type declaration", which allows one to introduce new features into existing classes. If your generated JAXWS class is called MyTypeGen, then you'd introduce new methods using an aspect (arbitrarily named MyTypeAspect) like this:

// generated class
class MyTypeGen  {      
    int x, y;

    public void setX(int x) { this.x = x; }
    public void setY(int y) { this.y = y; }
}

// introduce two new methods into MyTypeGen
aspect MyTypeAspect {
    public int MyTypeGen.multiply() {
        return x * y;
    }
    public int MyTypeGen.sum() {
        return x + y;
    }
}

At runtime, you can call those two new methods which have been weaved into MyTypeGen at build-time. No casting needed.

MyTypeGen mytype = new MyTypeGen();
mytype.setX(3);
mytype.setY(4);
int product = mytype.multiply();
// product = 12

If you decide to use Spring AOP instead, you'd create a normal Java class with the @Aspect annotation, in which you'd leverage the introductions feature.