Springboot freemark自定义标签

矫情吗；* 2022-04-15 06:06 291阅读 0赞

spring-boot开发网站使用freemarker里的自定义标签方法

创建类实现 TemplateDirectiveModel 类

@Component
    public class UserTopicDirective implements TemplateDirectiveModel {
    
      @Autowired
      private UserService userService;
      @Autowired
      private TopicService topicService;
    
      @Override
      public void execute(Environment environment, Map map, TemplateModel[] templateModels,
                          TemplateDirectiveBody templateDirectiveBody) throws TemplateException, IOException {
        Page<Topic> page = new PageImpl<>(new ArrayList<>());
        if (map.containsKey("username") && map.get("username") != null) {
          String username = map.get("username").toString();
          if (map.containsKey("p")) {
            int p = map.get("p") == null ? 1 : Integer.parseInt(map.get("p").toString());
            int limit = Integer.parseInt(map.get("limit").toString());
            User currentUser = userService.findByUsername(username);
            if (currentUser != null) {
              page = topicService.findByUser(p, limit, currentUser);
            }
          }
        }
        DefaultObjectWrapperBuilder builder = new DefaultObjectWrapperBuilder(Configuration.VERSION_2_3_25);
        environment.setVariable("page", builder.build().wrap(page));
        templateDirectiveBody.render(environment.getOut());
      }
    }

## 创建配置类 ##

@Component
    public class FreemarkerConfig {
     
      @Autowired
      private Configuration configuration;
      @Autowired
      private UserTopicDirective userTopicDirective;
     
      @PostConstruct
      public void setSharedVariable() throws TemplateModelException {
        configuration.setSharedVariable("user_topics_tag", userTopicDirective);
      }
     
    }

## 用法 ##

跟自定义macro用法一样，直接使用 `<@xx></@xx>` 来使用即可，值就直接在 user\_topics\_tag 标签里传就可以了

<@user_topics_tag username='tomoya' p=1 limit=10>
      <#list page.getContent() as topic>
        <p>${topic.title!}</p>
      </#list>
    </@user_topics_tag>

## 扩展 ##

FreemarkerConfig类不止可以加入自定义的标签，还可以加入系统自定义的变量等，下面举例说明

spring-boot里的配置文件

# application.yml
    site:
      baseUrl: http://localhost:8080/

对应的类是 `SiteConfig.java` 要取里面的值，使用方法如下

@Autowired
    private SiteConfig siteConfig;
    
    //...
    siteConfig.getBaseUrl();

如果把siteConfig加入到freemarker的configuration里就可以直接在freemarker页面上使用变量了

@PostConstruct
    public void setSharedVariable() throws TemplateModelException {
      configuration.setSharedVariable("site", siteConfig);
      configuration.setSharedVariable("user_topics_tag", userTopicDirective);
    }

页面里就可以这样来取值