A very simple Java String template renderer based on Java Reflection API

StringTemplateRenderer

public class StringTemplateRenderer {
    private static final Logger log = LoggerFactory.getLogger(StringTemplateRenderer.class);

    public String render(String templateString, RenderContext context) {
        final List<String> expressions = getExpressions(templateString);
        // each expression is turned into a value
        Stream<String> values = expressions.stream()
                .map(e -> resolve(context, getMethods(e)))
                .map(v -> v+"");
        String format = templateString.replaceAll("\\{.*?\\}", "%s");

        return String.format(format, values.toArray());
    }

    private List<String> getExpressions(String subject) {
        List<String> expressions = Lists.newArrayList();
        Matcher m = Pattern.compile("\\w*\\{(.*?)\\}").matcher(subject);
        while (m.find()) {
            String expression = m.group(1);
            expressions.add(expression);
        }
        return expressions;
    }

    private List<String> getMethods(String expression) {
        return Arrays.stream(expression.split("\\."))
                .map(m -> "get" + m.substring(0, 1).toUpperCase() + m.substring(1))
                .collect(Collectors.toList());
    }

    private Object resolve(Object o, List<String> methods)  {
        if (methods.size() == 0) return o;

        if (o instanceof RenderContext) {
            String key = methods.get(0).replace("get", "");
            key = key.substring(0, 1).toLowerCase() + key.substring(1);
            Object result = ((RenderContext) o).get(key);
            methods.remove(0);
            return resolve(result, methods);
        }
        Object result = null;
        try {
            Method m = o.getClass().getMethod(methods.get(0));
            result = m.invoke(o);
        } catch (NoSuchMethodException e) {
            log.error(e.getMessage(), e);
            return String.format("[ERR: Method not found %s.%s]", o.getClass().getSimpleName(), methods.get(0));
        } catch (IllegalAccessException e) {
            log.error(e.getMessage(), e);
            return String.format("[ERR: %s: %s/%s]", e.getMessage(), o.getClass().getSimpleName(), methods.get(0));
        } catch (InvocationTargetException e) {
            log.error(e.getMessage(), e);
            return String.format("[ERR: %s: %s/%s]", e.getMessage(), o.getClass().getSimpleName(), methods.get(0));
        }
        if (result == null) {
            return String.format("[ERR: %s.%s is NULL]", o.getClass().getSimpleName(), methods.get(0));
        }
        methods.remove(0);
        return resolve(result, methods);

    }

}