How to resolve the name properly by BeanELResolver

Question

we have to work with a very specific class in Java that has the following property:

protected SPSExchangedDocumentType spsExchangedDocument;

public SPSExchangedDocumentType getSPSExchangedDocument() {
  return spsExchangedDocument;
}

I use the instance of that class inside a jsp page:

<c:out value = "${certificate.spsExchangedDocument.id.value}"/>

It throws me the following exception:

javax.el.PropertyNotFoundException: The class 'un.unece.uncefact.data.standard.spscertificate._5.SPSCertificateType' does not have the property 'spsExchangedDocument'. at javax.el.BeanELResolver.getBeanProperty(BeanELResolver.java:579) at javax.el.BeanELResolver.getValue(BeanELResolver.java:281) at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:175) at com.sun.el.parser.AstValue.getValue(AstValue.java:138) at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:206) at org.apache.jasper.runtime.PageContextImpl.evaluateExpression(PageContextImpl.java:1001)

I think the problem is directly with the fact, that the property is called spsExchangedDocument, but the method is called getSPSExchangedDocument. I cannot change the code of the class, because it's generated automatically from XSD, that we cannot alter, so I should change the page. But what name should I use in order for EL to resolve it properly:

• spsExchangedDocument.
• SPSExchangedDocument.
• sPSExchangedDocument.

What is the rule for such naming conventions in java and EL anyway?

Answer 1

Assuming the BeanELResolver implementation conforms to the JavaBeans spec:

8.8 Capitalization of inferred names.

Thus when we extract a property or event name from the middle of an existing Java name, we normally convert the first character to lower case. However to support the occasional use of all upper-case names, we check if the first two characters of the name are both upper case and if so leave it alone. So for example,

• “FooBah” becomes “fooBah”
• “Z” becomes “z”
• “URL” becomes “URL”

The java.beans API resolves the property name as SPSExchangedDocument:

import java.beans.*;

public class Bean {
  public Object getSPSExchangedDocument() {
    return null;
  }

  public static void main(String[] args) throws IntrospectionException {
    BeanInfo info = Introspector.getBeanInfo(Bean.class);
    for (PropertyDescriptor prop : info.getPropertyDescriptors()) {
      System.out.println(prop.getName());
    }
  }
}

That said, there have been bugs in this area before.