如何指定 ObjectWrapper Freemarker

Question

请帮帮我。我的网络应用程序使用 Spring MVC 和 Freemarker 2.3.23。当我开始申请时，我有： "WARNING: Custom EL functions won't be loaded because no ObjectWrapper was specified" 。我尝试通过以下几种方式指定 ObjectWrapper：

@Configuration
public class CustomFreemarkerConfiguration extends WebMvcConfigurerAdapter {
@Bean
@Autowired
public TaglibFactory taglibFactory(ServletContext servletContext) throws 
 IOException, TemplateException {
    DefaultObjectWrapperBuilder owb = new 
DefaultObjectWrapperBuilder(freemarker.template.
Configuration.VERSION_2_3_23);
    owb.setForceLegacyNonListCollections(false);
    owb.setDefaultDateType(TemplateDateModel.DATETIME);
    DefaultObjectWrapper build = owb.build();
    TaglibFactory taglibFactory = new TaglibFactory(servletContext);
    taglibFactory.setObjectWrapper(build);
    return taglibFactory;
}
}

或

@Configuration
public class CustomFreemarkerConfiguration extends WebMvcConfigurerAdapter {
@Bean
public    DefaultObjectWrapper getDefaultObjectWrapper() {
    DefaultObjectWrapperBuilder defaultObjectWrapperBuilder = new 
DefaultObjectWrapperBuilder(freemarker.template.
Configuration.VERSION_2_3_23);
    defaultObjectWrapperBuilder.setExposeFields(true);
    DefaultObjectWrapper defaultObjectWrapper = 
defaultObjectWrapperBuilder.build();
    return defaultObjectWrapper;
}
}

或

@Configuration
public class CustomFreemarkerConfiguration extends WebMvcConfigurerAdapter {
...
@Bean
@Autowired
public TaglibFactory taglibFactory(ServletContext servletContext) throws 
IOException, TemplateException {
    FreeMarkerConfigurer freemarkerConfig = 
configFreeMarkerConfigurer(servletContext);

    TaglibFactory taglibFactory = freemarkerConfig.getTaglibFactory();

taglibFactory.setObjectWrapper(freemarker.template.Configuration.
getDefaultObjectWrapper(freemarker.template.Configuration.getVersion()));

    return taglibFactory;
}
...
}

但一直没有成功。也许有人有工作示例代码来指定 ObjectWrapper？

Answer 1

查看 FreeMarkerConfigurer 的源代码：它在收到 ServletContext 时重新创建 TaglibFactory，但不设置其 ObjectWrapper。所以你需要覆盖那个方法，然后调用 taglibFactory.setObjectWrapper(configuration.getObjectWrapper())。请注意，我假设 configuration 在那里总是最终的；我还没有检查过。（我不建议使用其他 ObjectWrapper，但 Configuration 包含的那个。所以你需要最后的 Configuration。）

创建一个 FreeMarkerConfigurer 子类的实例，作为 @Bean，让我们看看 Spring MVC 是否能接受它。（我不知道，我没试过。）

如果有效，则应在 Spring Jira 中报告此修复。

Answer 2

谢谢@ddekany 的回答，现在我的 WebConfig 如下所示：

 @Configuration
    @EnableWebMvc
    @ComponentScan(basePackages = "aquaplant")
    public class WebConfig extends WebMvcConfigurerAdapter {

    @Autowired
    public FreeMarkerConfigurer freeMarkerConfigurer;

    @Autowired
    public DefaultObjectWrapper defaultObjectWrapper;

    @Bean
    public ViewResolver getViewResolver() {
        FreeMarkerViewResolver resolver = new FreeMarkerViewResolver();
        resolver.setOrder(1);
        resolver.setSuffix(".ftl");
        resolver.setPrefix("");
        resolver.setExposeSpringMacroHelpers(true);
        resolver.setExposeRequestAttributes(true);
        resolver.setExposeSessionAttributes(true);
        resolver.setRequestContextAttribute("request");
        return resolver;
    }

    @Bean
    public FreeMarkerConfigurer getFreeMarkerConfigurer() {
        FreeMarkerConfigurer configurer = new FreeMarkerConfigurer();
        configurer.setTemplateLoaderPaths("/", "/WEB-INF/views");
        return configurer;
    }
    @Bean
    public DefaultObjectWrapper defaultObjectWrapper(){
        DefaultObjectWrapperBuilder owb=new DefaultObjectWrapperBuilder
                (freemarker.template.Configuration.VERSION_2_3_23);
        owb.setForceLegacyNonListCollections(false);
        DefaultObjectWrapper objectWrapper = owb.build();
        return objectWrapper;
    }
    @Bean
    @Autowired
    public TaglibFactory taglibFactory(ServletContext servletContext) throws
            IOException, TemplateException {
        freeMarkerConfigurer.setServletContext(servletContext);
        TaglibFactory taglibFactory = freeMarkerConfigurer.getTaglibFactory();
        taglibFactory.setObjectWrapper(defaultObjectWrapper);
        return taglibFactory;
    }

    }

我没有任何 "WARNING"，但在我的注册页面上我无法收到错误消息。这条鳕鱼不起作用：

  <div class="form-group">
        <@spring.bind "userForm"/>
          <#if spring.status.error>
            <div class="alert alert-danger" role="alert">
              <#list spring.status.errorMessages as error>
               <li>${error}</li>
              </#list>
            </div>
        </#if>
        <label for="username">Username</label>
        <input type="text" class="form-control" id="username" 
            placeholder="Username" name="username">    
  </div>

我哪里做错了？

Answer 3

最后，我重写了 getTaglibFactory()：

import freemarker.ext.jsp.TaglibFactory;
import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer;

public class DefaultFreeMarkerConfigurer extends FreeMarkerConfigurer{
    @Override
    public TaglibFactory getTaglibFactory() {
        TaglibFactory tagLibFactory = super.getTaglibFactory();
        if (tagLibFactory.getObjectWrapper()==null) {
            tagLibFactory.setObjectWrapper(super.getConfiguration().getObjectWrapper());
        }
        return tagLibFactory;
    }
}

它似乎有效。

如何指定 ObjectWrapper Freemarker

How to specify ObjectWrapper Freemarker

spring

freemarker