如何在Spring Boot中自定义Thymeleaf的标签和属性

要在Spring Boot中自定义Thymeleaf的标签和属性，你需要遵循以下步骤：

1. 添加Thymeleaf依赖

确保你的项目中已经添加了Thymeleaf的依赖。在pom.xml文件中添加以下内容：

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

2. 创建自定义标签处理器

首先，创建一个类，实现IProcessor接口，用于处理自定义标签。例如，我们创建一个名为CustomTagProcessor的类：

import org.thymeleaf.context.ITemplateContext;
import org.thymeleaf.model.IProcessableElementTag;
import org.thymeleaf.processor.element.AbstractElementTagProcessor;
import org.thymeleaf.processor.element.IElementTagStructureHandler;
import org.thymeleaf.templatemode.TemplateMode;

public class CustomTagProcessor extends AbstractElementTagProcessor {

    private static final String TAG_NAME = "custom";
    private static final int PRECEDENCE = 1000;

    public CustomTagProcessor(String dialectPrefix) {
        super(TemplateMode.HTML, dialectPrefix, TAG_NAME, true, null, false, PRECEDENCE);
    }

    @Override
    protected void doProcess(ITemplateContext context, IProcessableElementTag tag, IElementTagStructureHandler structureHandler) {
        // 在这里处理自定义标签的逻辑
        String attributeValue = tag.getAttributeValue("attributeName");
        // ... 根据属性值进行相应的处理
    }
}

3. 创建自定义属性处理器

与创建自定义标签处理器类似，创建一个实现IProcessor接口的类，用于处理自定义属性。例如，我们创建一个名为CustomAttributeProcessor的类：

import org.thymeleaf.context.ITemplateContext;
import org.thymeleaf.model.IProcessableElementTag;
import org.thymeleaf.processor.element.AbstractAttributeTagProcessor;
import org.thymeleaf.processor.element.IElementTagStructureHandler;
import org.thymeleaf.templatemode.TemplateMode;

public class CustomAttributeProcessor extends AbstractAttributeTagProcessor {

    private static final String ATTR_NAME = "customAttr";
    private static final int PRECEDENCE = 1000;

    public CustomAttributeProcessor(String dialectPrefix) {
        super(TemplateMode.HTML, dialectPrefix, null, false, ATTR_NAME, true, PRECEDENCE);
    }

    @Override
    protected void doProcess(ITemplateContext context, IProcessableElementTag tag, AttributeName attributeName, String attributeValue, IElementTagStructureHandler structureHandler) {
        // 在这里处理自定义属性的逻辑
        // ... 根据属性值进行相应的处理
    }
}

4. 创建自定义方言

接下来，创建一个实现IDialect接口的类，用于注册自定义标签和属性处理器。例如，我们创建一个名为CustomDialect的类：

import org.thymeleaf.dialect.AbstractProcessorDialect;
import org.thymeleaf.processor.IProcessor;

import java.util.HashSet;
import java.util.Set;

public class CustomDialect extends AbstractProcessorDialect {

    private static final String DIALECT_NAME = "Custom Dialect";
    private static final String DIALECT_PREFIX = "custom";

    public CustomDialect() {
        super(DIALECT_NAME, DIALECT_PREFIX, 1000);
    }

    @Override
    public Set<IProcessor> getProcessors(String dialectPrefix) {
        Set<IProcessor> processors = new HashSet<>();
        processors.add(new CustomTagProcessor(dialectPrefix));
        processors.add(new CustomAttributeProcessor(dialectPrefix));
        return processors;
    }
}

5. 注册自定义方言

最后，需要将自定义方言注册到Thymeleaf中。创建一个配置类，继承WebMvcConfigurer，并重写addViewControllers方法，将自定义方言添加到templateEngine中：

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.thymeleaf.spring5.SpringTemplateEngine;
import org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver;
import org.thymeleaf.spring5.view.ThymeleafViewResolver;

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Bean
    public SpringResourceTemplateResolver templateResolver() {
        SpringResourceTemplateResolver templateResolver = new SpringResourceTemplateResolver();
        templateResolver.setPrefix("/WEB-INF/templates/");
        templateResolver.setSuffix(".html");
        return templateResolver;
    }

    @Bean
    public SpringTemplateEngine templateEngine() {
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        templateEngine.setTemplateResolver(templateResolver());
        templateEngine.setEnableSpringELCompiler(true);
        templateEngine.addDialect(new CustomDialect());
        return templateEngine;
    }

    @Bean
    public ThymeleafViewResolver viewResolver() {
        ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
        viewResolver.setTemplateEngine(templateEngine());
        return viewResolver;
    }
}

现在，你可以在Thymeleaf模板中使用自定义标签和属性了。例如：

<!DOCTYPE html>
<html xmlns:custom="http://www.example.com/custom">
<head>
    <title>Custom Tag and Attribute Example</title>
</head>
<body>
    <custom:custom attributeName="value">Content</custom:custom>
    <div custom:customAttr="value">Content</div>
</body>
</html>

这样，当Thymeleaf解析到<custom:custom>标签或包含custom:customAttr属性的元素时，它会调用相应的处理器来处理这些元素。