Spring, property file, empty values

I cannot explain it, but I think you can fix your problem using defaulting syntax, available since Spring 3.0.0.RC1 (see).

In the chageg log you can read: PropertyPlaceholderConfigurer supports "${myKey:myDefaultValue}" defaulting syntax

Anyway, I think that the problem is because "" is valid value, but no value in the property file don't.

Ok, I think this is a spring security bug.

If I debug and look at the class LdapServerBeanDefinition, there is a method called "parse". Here is an extract:

public BeanDefinition parse(Element elt, ParserContext parserContext) {
    String url = elt.getAttribute(ATT_URL);

    RootBeanDefinition contextSource;

    if (!StringUtils.hasText(url)) {
        contextSource = createEmbeddedServer(elt, parserContext);
    } else {
        contextSource = new RootBeanDefinition();
        contextSource.setBeanClassName(CONTEXT_SOURCE_CLASS);
        contextSource.getConstructorArgumentValues().addIndexedArgumentValue(0, url);
    }

    contextSource.setSource(parserContext.extractSource(elt));

    String managerDn = elt.getAttribute(ATT_PRINCIPAL);
    String managerPassword = elt.getAttribute(ATT_PASSWORD);

    if (StringUtils.hasText(managerDn)) {
        if(!StringUtils.hasText(managerPassword)) {
            parserContext.getReaderContext().error("You must specify the " + ATT_PASSWORD +
                    " if you supply a " + managerDn, elt);
        }

        contextSource.getPropertyValues().addPropertyValue("userDn", managerDn);
        contextSource.getPropertyValues().addPropertyValue("password", managerPassword);
    }

    ...
}

If I debug here, all variables (url, managerDn, managerPassword...) are not replaced by the value specified in the property file. And so, url has the value ${ldap.server.url}, managerDn has the value ${ldap.server.manager.dn} and so on.

The method parse creates a bean, a context source that will be used further. And when this bean will be used, place holders will be replaced.

Here, we got the bug. The parse method check if url is empty or not. The problem is that url is not empty here because it has the value ${ldap.server.url}. So, the parse method creates a context source as a distant server.

When the created source will be used, it will replace the ${ldap.server.url} by empty value (like specified in the property file). And....... Bug !

I don't know really how to solve this for the moment, but I now understand why it bugs ;)