struts2, freemarker: load template from memory

1. register in struts.xml


2. Extends FreeMarkerManager
public class FreeMarkerManager extends FreemarkerManager {
    protected TemplateLoader getTemplateLoader(ServletContext servletContext) {
        FormTemplateLoader templateLoader = new FormTemplateLoader();

        return new MultiTemplateLoader(new TemplateLoader[]{
                   templateLoader,
                   new WebappTemplateLoader(servletContext),
                   new StrutsClassTemplateLoader()
                });
    }
}

3. Implement TemplateLoader
public class FormTemplateLoader implements TemplateLoader {
  public Object findTemplateSource(String name) {
    // getTemplates() returns map containing template list with template name as key
    source = (String) getTemplates().get(name);
    lastModified = System.currentTimeMillis();
    return source;
  }

   ...
}

struts 2: integrate groovy batch

// Using groovy to find out next page by evaluating rule defined in form schema.
Binding binding = new Binding();
binding.setVariable("page", page);
GroovyShell shell = new GroovyShell(binding);
String result = (String) shell.evaluate(page.getFlowRule());

struts 2: integrate ValangValidator

public void validate() {
    ValangValidator validator = new ValangValidator();
    
    Page page = getPage();
    if (page != null) {
        int index = 0;
        // Currently, this only provides field level validation.
        // TODO: add page/form level validation.
        for (index = 0; index < page.getFields().size(); index++) {
            Field field = (Field) page.getFields().get(index);
            if (field.getValidateRule() != null) {
                try {
                    // Use springmodules ValangValidator to validate field.
                    Errors errors = new BindException(field, "field");
                    String validateStr = field.getValidateRule();
                    validator.setValang(validateStr);
                    validator.afterPropertiesSet(); 
                    validator.validate(field, errors);
                    if (errors.getErrorCount() > 0) {
                        addFieldError("page.fields["+index+"].value", 
                        errors.getFieldError().getDefaultMessage());
                    }
                }
                catch(Exception e) {
                    LOG.error(e);
                    addActionError("Validation has failed: "+e.getMessage());
                }
            }
        }
    }
}