Spring Thymeleaf Extension Dialect Example

ThymeLeafConfig.java

@Configuration
public class ThymeLeafConfig {

    @Autowired
    private SpringResourceTemplateResolver templateResolver;

    @Bean
    public SpringTemplateEngine templateEngine(){
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        templateEngine.setEnableSpringELCompiler(true);
        templateEngine.setTemplateResolver(templateResolver);
        templateEngine.addDialect(new MyDialect());
        return templateEngine;
    }

}


class MyDialect extends AbstractProcessorDialect {

    public MyDialect() {
        super("My Dialect", "example", StandardDialect.PROCESSOR_PRECEDENCE);
    }

    @Override
    public Set<IProcessor> getProcessors(String dialectPrefix) {
        Set<IProcessor> processors = new HashSet<>();
        processors.add(new MyCSSTagProcessor(dialectPrefix));
        return processors;
    }

}

class MyCSSTagProcessor extends AbstractAttributeTagProcessor {
    /*
     * Example usage: <i example:updateCSS="${value}"></i>
     */
  
    private static final String ATTR_NAME = "updateCSS";
    private static final int PRECEDENCE = 10000;

    public MyCSSTagProcessor(String dialectPrefix) {
        super(TemplateMode.HTML, dialectPrefix, null, false, ATTR_NAME, true, PRECEDENCE, true);
    }

    @Override
    protected void doProcess(ITemplateContext context,
                             IProcessableElementTag tag,
                             AttributeName attributeName,
                             String attributeValue,
                             IElementTagStructureHandler structureHandler) {
        IEngineConfiguration configuration = context.getConfiguration();
        IStandardExpressionParser parser = StandardExpressions.getExpressionParser(configuration);
        IStandardExpression expression = parser.parseExpression(context, attributeValue);
        String value = (String) expression.execute(context);
        structureHandler.setAttribute("class", value);
    }

}