thymeleaf自定义标签

前言

使用thymeleaf自定义标签，环境：springboot 2.3.7 + thymeleaf 3.0.11(2021-01-14最新版)
由于使用shiro，我们需要与thymeleaf整合一些标签方便更好操作，以isAuthenticated为例。
ps：虽然有一个开源的框架，但是很久没维护了，还不如照着官网来自定义。

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-thymeleaf</artifactId>
      <version>2.3.7.RELEASE</version>
    </dependency>

参考官方文档：https://www.thymeleaf.org/doc/tutorials/3.0/extendingthymeleaf.html
官方demo：https://github.com/thymeleaf/thymeleafexamples-extrathyme

一、创建方言

前缀仍然使用th

package com.example.shirodemo.config.thymeleaf;

import java.util.HashSet;
import java.util.Set;
import org.thymeleaf.dialect.AbstractProcessorDialect;
import org.thymeleaf.processor.IProcessor;
import org.thymeleaf.standard.StandardDialect;

/**
 * @author 绫小路
 * @date 2021/1/14 22:43
 * @description
 */
public class ShiroDialect extends AbstractProcessorDialect {

  private static final String DIALECT_NAME = "shiro方言";

  public ShiroDialect() {
    // We will set this dialect the same "dialect processor" precedence as
    // the Standard Dialect, so that processor executions can interleave.
    super(DIALECT_NAME, "th", StandardDialect.PROCESSOR_PRECEDENCE);
  }

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

二、标签处理

package com.example.shirodemo.config.thymeleaf;

import static org.thymeleaf.standard.processor.StandardWithTagProcessor.PRECEDENCE;

import org.apache.shiro.SecurityUtils;
import org.apache.shiro.subject.Subject;
import org.thymeleaf.context.ITemplateContext;
import org.thymeleaf.engine.AttributeName;
import org.thymeleaf.model.IProcessableElementTag;
import org.thymeleaf.processor.element.AbstractAttributeTagProcessor;
import org.thymeleaf.processor.element.IElementTagStructureHandler;
import org.thymeleaf.templatemode.TemplateMode;

/**
 * @author 绫小路
 * @date 2021/1/14 23:02
 * @description
 */
public class AuthTagProcessor extends AbstractAttributeTagProcessor {

  private static final String SHIRO = "shiro";

  public AuthTagProcessor(String dialectPrefix) {
    super(
        TemplateMode.HTML, // This processor will apply only to HTML mode
        dialectPrefix,     // Prefix to be applied to name for matching 前缀
        null,              // No tag name: match any tag name
        false,             // No prefix to be applied to tag name
        SHIRO,         // Name of the attribute that will be matched
        true,              // Apply dialect prefix to attribute name
        PRECEDENCE,        // Precedence (inside dialect's own precedence)优先级
        true);             // Remove the matched attribute afterwards
//    super( TemplateMode.HTML, dialectPrefix, elementName, prefixElementName, isAuthenticated, prefixAttributeName, precedence, removeAttribute);
  }

  @Override
  protected void doProcess(ITemplateContext context, IProcessableElementTag tag, AttributeName attributeName, String attributeValue,
      IElementTagStructureHandler structureHandler) {
    Subject subject = SecurityUtils.getSubject();
    if ("isAuthenticated".equals(attributeValue)) {//判断是否登录
      if (!subject.isAuthenticated()) {
        structureHandler.removeElement();//未登录时将元素移除  例如<a href="/admin" th:shiro="isAuthenticated">admin</a>
      }
    }
  }
}

三、配置

直接交给spring容器管理即可

  @Bean
  public ShiroDialect shiroDialect() {
    return new ShiroDialect();//添加自定义的标签
  }

四、使用

index.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<body>
首页 <a href="/login">登录</a>
<br>
<a href="/logout" th:shiro="isAuthenticated">注销</a>
<br>
<a href="/admin" th:shiro="isAuthenticated">admin</a>
</body>
</html>

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