Java - xml文档如何使用XML目录加载DTD？

<!DOCTYPE rootElement SYSTEM "path/to/dtd/file.dtd">

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.Document;

// 创建XML解析器的工厂实例
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

// 开启验证模式，以便加载DTD
factory.setValidating(true);

// 创建XML解析器对象
DocumentBuilder builder = factory.newDocumentBuilder();

// 加载XML文档
Document document = builder.parse(new File("path/to/xml/file.xml"));

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;

// 定义实体解析器的实现类
EntityResolver resolver = new EntityResolver() {
    @Override
    public InputSource resolveEntity(String publicId, String systemId) {
        if (systemId.endsWith("file.dtd")) {
            // 加载DTD文件
            return new InputSource(new FileInputStream("path/to/dtd/file.dtd"));
        }
        return null;
    }
};

// 设置XML解析器的实体解析器
builder.setEntityResolver(resolver);