JAXB marshalling for BigDecimal using fractionDigits

Question

So here's my problem. I'm given an XSD to which my generated XML file should comply. Using the org.apache.cxf.cxf-xjc-plugin maven plugin and an external binding file I generate the source code. But when I'm trying marshall my object the generated XML doesn't meet my requirements.

My XSD contains the following:

<xsd:element maxOccurs="1" minOccurs="0" name="amount">
  <xsd:simpleType>
    <xsd:restriction base="xsd:decimal">
      <xsd:totalDigits value="13" />
      <xsd:fractionDigits value="2" />
    </xsd:restriction>
  </xsd:simpleType>
</xsd:element>
...
<xsd:element maxOccurs="1" minOccurs="0" name="rate">
  <xsd:simpleType>
    <xsd:restriction base="xsd:decimal">
      <xsd:totalDigits value="8" />
      <xsd:fractionDigits value="5" />
    </xsd:restriction>
  </xsd:simpleType>
</xsd:element>

And the generated piece of XML looks like this:

<amount>109.5</amount>
...
<rate>10.25</rate>

While I was expecting it to be:

<amount>109.50</amount>
...
<rate>10.25000</rate>

Is there a way to solve this problem in a clean way?

I would prefer not writing several adapters for every single totalDigits, fractionDigits combination. And as the XSD is subject to change I'd like to leave the generated source code untouched.

The w3c document on the decimal datatype says `fractionDigits` specifies the upper limit on the number of digits after the decimal separator. It should not matter to anything reading the data if the right-hand zeros are absent. What is the use case that requires the zero padding? — Jim Garrison, Feb 13 '13 at 08:18
@Jim The (legacy) application parsing my generated XML file requires the zero padding ;-) — Jasper, Feb 13 '13 at 08:26

score 6 · Accepted Answer · edited Dec 05 '13 at 20:18

You will need to use XmlAdapter for this use case. Below is a sample binding file that will help you generate them. The logic would be contained in a DecimalFormatter class that contained methods for all the different required formats.

<jxb:bindings xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:jxb="http://java.sun.com/xml/ns/jaxb" version="2.1">
    <jxb:bindings schemaLocation="schema.xsd">
        <jxb:bindings node="//xs:element[@name='amount']">
            <jxb:property>
                <jxb:baseType>
                    <jxb:javaType name="java.math.BigDecimal"
                        parseMethod="org.example.DecimalFormatter.parseDecimal"
                        printMethod="org.example.DecimalFormatter.printDecimal_2Places" />
                </jxb:baseType>
            </jxb:property>
        </jxb:bindings>
        <jxb:bindings node="//xs:element[@name='rate']">
            <jxb:property>
                <jxb:baseType>
                    <jxb:javaType name="java.math.BigDecimal"
                        parseMethod="org.example.DecimalFormatter.parseDecimal"
                        printMethod="org.example.DecimalFormatter.printDecimal_5Places" />
                </jxb:baseType>
            </jxb:property>
        </jxb:bindings>
    </jxb:bindings>
</jxb:bindings>

For More Information

http://blog.bdoughan.com/2011/08/xml-schema-to-java-generating.html

I'm actually doing this right now, but I'm trying to find a *cleaner* solution since this requires me to create a `printMethod` for every `totalDigits` - `fractionDigits` combination. — Jasper, Feb 13 '13 at 11:00

score 1 · Answer 2 · answered Jan 28 '19 at 11:45

I've created some special XmlAdapter, for example

public class BigDecimal8PlaceAdapter extends XmlAdapter<String, BigDecimal> {

@Override
public String marshal(BigDecimal v) throws Exception {
  DecimalFormatSymbols otherSymbols = new DecimalFormatSymbols();
  otherSymbols.setDecimalSeparator('.');
  DecimalFormat df = new DecimalFormat("#0.00000000",otherSymbols);
  return df.format(v);
}

@Override
public BigDecimal unmarshal(String v) throws Exception {
    Double d = Double.valueOf(v);
    return BigDecimal.valueOf(d);
}

}

then i add the XmlAdapter in the properties:

@XmlElement(name = "rate", required = true)
@XmlJavaTypeAdapter(BigDecimal8PlaceAdapter.class)
protected BigDecimal rate;

Then, do the same thing with 2 decimals adapeter.

score 0 · Answer 3 · answered Feb 13 '13 at 08:20

0

If you can change the XSD to use the precisionDecimal type documented here you might be able to use the minScale and maxScale facets set to the same value.

answered Feb 13 '13 at 08:20

Jim Garrison

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According to [this answer](http://stackoverflow.com/a/4901771/321366), the JAXB spec does not cover converting XML Schema 1.1 to Java. And XJC throws the following exception `[ERROR] src-resolve: Cannot resolve the name 'xsd:precisionDecimal' to a(n) 'type definition' component.` when I try it. – Jasper Feb 13 '13 at 09:55

score 0 · Answer 4 · edited May 23 '17 at 11:56

I'm confused as to what could possibly be gained by maintaining the trailing zeros.

If the trailing zeros are that important to preserve, then use a string value instead of a number and use attributes to specify its width and decimals.

In any case, the trailing zeros will never impact calculations using any of these values, and the only way you would be able to present them is by converting the results into a string and padding it yourself. For some help doing that, you may want to see...

CXF client SOAP message formatting

JAXB marshalling for BigDecimal using fractionDigits

4 Answers4

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