freemarker+sitemesh3装饰器不能渲染ftl标签的解决方案

找了网上那么多，没有一个可以直接用的，由于最近在做这方面的调研，把经验心得分享给大家

1、需要把参数传递到freemarker渲染视图的地方

2、装饰器的拦截器优先级在最后

一、获取要渲染的参数

 这些参数一般在controller里放的，但是要传递到filter里，需要费一番功夫

例如我要在装饰器里获取这个变量

${headerCssJsVersion}

Controller代码

    @RequestMapping("/a")
    public String a(Model model) {

        model.addAttribute("headerCssJsVersion", "202511051509");

        return "test_zjs";
    }

可以利用spring自带的类，来做上下文传递，当然自己写threadLocal也可以做到

我用的是spring自带的是这段代码

		RequestContextHolder.currentRequestAttributes().setAttribute(LocalFtlConstant.LOCAL_FTL_MODEL_KEY, modelAndView.getModel(), PageContext.SESSION_SCOPE);

传递参数的拦截器全代码：

import com.dhgate.center.admin.constant.LocalFtlConstant;
import com.dhgate.center.admin.core.util.FtlUtil;
import com.dhgate.center.admin.core.util.I18nUtil;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.servlet.AsyncHandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.PageContext;
import java.util.HashMap;

/**
 * @Description:  cookie拦截、装载
 * @Author: zhangjianshou
 * @Date: 2025/2/7 15:00
 */
@Component
public class CookieInterceptor implements AsyncHandlerInterceptor {


	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
		return AsyncHandlerInterceptor.super.preHandle(request, response, handler);
	}

	@Override
	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
			ModelAndView modelAndView) throws Exception {

		// cookie
		if (modelAndView!=null && request.getCookies()!=null && request.getCookies().length>0) {
			HashMap<String, Cookie> cookieMap = new HashMap<String, Cookie>();
			for (Cookie ck : request.getCookies()) {
				cookieMap.put(ck.getName(), ck);
			}
			modelAndView.addObject("cookieMap", cookieMap);
		}

		// static method
		if (modelAndView != null) {
			//国际化数据
			modelAndView.addObject("I18nUtil", FtlUtil.generateStaticModel(I18nUtil.class.getName()));

			// 将modelAndView中的数据放入request中，方便在ftl装饰器渲染页面中使用
			RequestContextHolder.currentRequestAttributes().setAttribute(LocalFtlConstant.LOCAL_FTL_MODEL_KEY, modelAndView.getModel(), PageContext.SESSION_SCOPE);

		}

	}
	
}

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import javax.annotation.Resource;

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {


    @Resource
    private CookieInterceptor cookieInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(cookieInterceptor).addPathPatterns("/**").order(1);

    }
}

二、sitemesh3装饰器，渲染freemarker的页面拦截器：

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.servlet.DispatcherType;
import java.util.EnumSet;

@Configuration
public class SitemeshFilterConfig {

    @Bean
    public FilterRegistrationBean<CustomFreemarkerFilter> customFreemarkerFilter(freemarker.template.Configuration freemarkerConfig) {
        FilterRegistrationBean<CustomFreemarkerFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new CustomFreemarkerFilter(freemarkerConfig));
        // 配置过滤器 URL 模式
        registrationBean.addUrlPatterns("*.html");

        // 配置请求调度类型，包括请求和转发
        registrationBean.setDispatcherTypes(EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD));

        registrationBean.setOrder(1000); // 设置过滤器的执行顺序
        return registrationBean;
    }
}

装饰freemarker拦截器的实现代码：

import com.dhgate.center.admin.constant.LocalFtlConstant;
import com.dhgate.logging.Log;
import com.dhgate.logging.LogFactory;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.PageContext;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;

// FreeMarker自定义的过滤器
public class CustomFreemarkerFilter implements Filter {

    private static final Log log = LogFactory.getLogger(CustomFreemarkerFilter.class);


    private freemarker.template.Configuration freemarkerConfig;

    public CustomFreemarkerFilter(Configuration freemarkerConfig) {
        this.freemarkerConfig = freemarkerConfig;
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;


        String uri = req.getRequestURI();
        if (uri.endsWith(".html")) {
            try {
                Template template = freemarkerConfig.getTemplate(uri.substring(1)); // Remove leading '/'

                Map<String, Object> model = new HashMap<>();
//                model.put("headerCssJsVersion", "World");

                RequestAttributes requestAttributes = RequestContextHolder.currentRequestAttributes();

                Object modelGet = requestAttributes.getAttribute(LocalFtlConstant.LOCAL_FTL_MODEL_KEY, PageContext.SESSION_SCOPE);
                if (modelGet != null) {
                    model = (Map<String, Object>) modelGet;
                }

                response.setContentType("text/html;charset=UTF-8");
                PrintWriter writer = response.getWriter();
                template.process(model, writer);
            } catch (TemplateException e) {
                log.error("error when process template", e);
            }
        }

    }

    @Override
    public void destroy() {

    }
}

三、sitemesh3装饰器页面，参考：

<html>
  <head>
    <title>SiteMesh Example: <sitemesh:write property="title">Title goes here</sitemesh:write></title>



      <sitemesh:write property="head"/>
  </head>
  <body>

  ${headerCssJsVersion}

    <sitemesh:write property="body">33  Body goes here. Blah blah blah.</sitemesh:write>

  </body>
</html>