Question

Here is an example of my question:

1) I have an XML files where Rules for my Invoice are definded

<rules>
..
  <price>
   <Required>True</Required>
   <MinValue>0.1</MinValue>
  <price>
..
</rules>

2) I have an Invoice Object in java (important: this should stay so (plain). No annotations or anything should be included.)

public class Invoice implements Serializable {

    private String details;
    private String tax;
    private String recipient;
    private double price;

    //getter and setter

}

3) And at least I have a Validator Object

public class Validator(){

    public boolean validate(String xmlfile, Invoice i) {
           //todo: Invoice i should be validated with xmlfile
    }
}

What I need:
The Validator should take the XML File with the rules inside
e.g.

  <price>
   <Required>True</Required>
   <MinValue>0.1</MinValue>
  <price>

and use that rule to validate the Invoice java object.

Are there any good frameworks I could use for that? Or tutorials? Approaches?
Any help is really appreciated.

Thank you.

Answer 1

You can use Hibernate Validator which is implementation of JSR 303. You can write constrains in XML as below

<field name="x2"  ignore-annotations="true"    >  <!-- XML is stronger -->
        <constraint annotation="javax.validation.constraints.Min">
             <element name="value">2</element>
        </constraint>
    </field>

A complete and nice tutorial can be found here