Is there a PropertyPlaceholderConfigurer-like class for use with Spring that accepts XML?

Question

Spring has a very handy convenience class called PropertyPlaceholderConfigurer, which takes a standard .properties file and injects values from it into your bean.xml config.

Answer 1

I'm not sure about the Apache digester-style config files, but I found a solution that was not that hard to implement and suitable for my xml config-file.

You can use the normal PropertyPlaceholderConfigurer from spring, but to read your custom config you have to create your own PropertiesPersister, where you can parse the xml (with XPath) and set the required properties yourself.

Here's a small example:

First create your own PropertiesPersister by extending the default one:

public class CustomXMLPropertiesPersister extends DefaultPropertiesPersister {
            private XPath dbPath;
            private XPath dbName;
            private XPath dbUsername;
            private XPath dbPassword;

            public CustomXMLPropertiesPersister() throws JDOMException  {
                super();

            dbPath = XPath.newInstance("//Configuration/Database/Path");
            dbName = XPath.newInstance("//Configuration/Database/Filename");
            dbUsername = XPath.newInstance("//Configuration/Database/User");
            dbPassword = XPath.newInstance("//Configuration/Database/Password");
        }

        public void loadFromXml(Properties props, InputStream is)
        {
            Element rootElem = inputStreamToElement(is);

            String path = "";
            String name = "";
            String user = "";
            String password = "";

            try
            {
                path = ((Element) dbPath.selectSingleNode(rootElem)).getValue();
                name = ((Element) dbName.selectSingleNode(rootElem)).getValue();
                user = ((Element) dbUsername.selectSingleNode(rootElem)).getValue();
                password = ((Element) dbPassword.selectSingleNode(rootElem)).getValue();
            }
            catch (JDOMException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            props.setProperty("db.path", path);
            props.setProperty("db.name", name);
            props.setProperty("db.user", user);
            props.setProperty("db.password", password);
        }

        public Element inputStreamToElement(InputStream is)
        {       
            ...
        }

        public void storeToXml(Properties props, OutputStream os, String header)
        {
            ...
        }
    }

Then inject the CustomPropertiesPersister to the PropertyPlaceholderConfigurer in the application context:

After that you can use your properties like this: