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?

In general, the naming of the getters and setters are the name of the property with the first character capitalized and preceeded with get/set. So please try it with getSpsExchangedDocument. Normally this can be generated by your IDE of choice. — Mike de Dood, Feb 26 '14 at 12:08
Once again - I cannot change the name of the getter, because it's generated automatically by the Jaxb tool. — SPIRiT_1984, Feb 26 '14 at 12:19

score 1 · Accepted Answer · answered Feb 26 '14 at 12:23

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.

How to resolve the name properly by BeanELResolver

1 Answers1