// init the template engine
templateEngine = new SpringTemplateEngine();
templateResolver = new ClassLoaderTemplateResolver();
templateEngine.addTemplateResolver(templateResolver);

// generate the template
Context ctx = new Context(locale);
// i would like, for example, to format dates
ctx.setVariable("date", new Date());
String text = this.templateEngine.process(templateName, ctx);

Set<IDialect> dialects = this.templateEngine.getDialects();
StandardDialect standardDialect = (StandardDialect) dialects.iterator().next();
IStandardConversionService conversionService = new MyConversionService();
standardDialect.setConversionService(conversionService);

public MyConversionService implements IStandardConversionService {
    GenericConversionService myConverter = new MyConverter();
    StandardConversionService standardConversionService = new StandardConversionService();

    @Override
    public <T> T convert(Configuration configuration, IProcessingContext processingContext, Object object, Class<T> targetClass) {

        if (myConverter.canConvert(object.getClass(), targetClass)) {
            return myConverter.convert(object, targetClass);
        }

        return standardConversionService.convert(configuration, processingContext, object, targetClass);
    }
}

${{variable}}

<dependency>
    <groupId>org.thymeleaf</groupId>
    <artifactId>thymeleaf-spring4</artifactId>
    <version>2.1.4.RELEASE</version>
</dependency>

public class DateFormatter implements Formatter<Date> {

public DateFormatter() {
    super();
}

@Override
public Date parse(final String text, final Locale locale) throws ParseException {
    final SimpleDateFormat dateFormat = createDateFormat(locale);
    return dateFormat.parse(text);
}

@Override
public String print(final Date object, final Locale locale) {
    final SimpleDateFormat dateFormat = createDateFormat(locale);
    return dateFormat.format(object);
}

private SimpleDateFormat createDateFormat(final Locale locale) {
    final String format = "dd/MM/yyyy";
    final SimpleDateFormat dateFormat = new SimpleDateFormat(format, locale);
    dateFormat.setLenient(false);
    return dateFormat;
}