Email Internationalization using Velocity/FreeMarker Templates

Question

How can I achieve i18n using a templating engine such as Velocity or FreeMarker for constructing email body?

Typically people tend to create templates like:

Answer 1

Here's the solution (one template, several resource files) for Freemarker.

the main program

// defined in the Spring configuration file
MessageSource messageSource;

Configuration config = new Configuration();
// ... additional config settings

// get the template (notice that there is no Locale involved here)
Template template = config.getTemplate(templateName);

Map model = new HashMap();
// the method called "msg" will be available inside the Freemarker template
// this is where the locale comes into play 
model.put("msg", new MessageResolverMethod(messageSource, locale));

MessageResolverMethod class

private class MessageResolverMethod implements TemplateMethodModel {

  private MessageSource messageSource;
  private Locale locale;

  public MessageResolverMethod(MessageSource messageSource, Locale locale) {
    this.messageSource = messageSource;
    this.locale = locale;
  }

  @Override
  public Object exec(List arguments) throws TemplateModelException {
    if (arguments.size() != 1) {
      throw new TemplateModelException("Wrong number of arguments");
    }
    String code = (String) arguments.get(0);
    if (code == null || code.isEmpty()) {
      throw new TemplateModelException("Invalid code value '" + code + "'");
    }
    return messageSource.getMessage(code, null, locale);
  }

}

Freemarker template

${msg("subject.title")}