尝试使用Apache Tika和XPath获取属性值

import org.apache.tika.Tika;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.parser.ParseContext;
import org.apache.tika.parser.pdf.PDFParser;
import org.apache.tika.sax.BodyContentHandler;
import org.w3c.dom.Document;
import org.xml.sax.ContentHandler;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;

public class TikaXPathExample {
    public static void main(String[] args) throws Exception {
        // 创建 Tika 实例
        Tika tika = new Tika();
        // 创建 PDF 解析器
        PDFParser pdfParser = new PDFParser();
        // 创建内容处理器
        ContentHandler handler = new BodyContentHandler(-1);
        // 创建解析上下文
        ParseContext pcontext = new ParseContext();

        // 打开 PDF 文件
        File file = new File("example.pdf");
        try (InputStream inputstream = new FileInputStream(file)) {
            // 解析 PDF 文件
            pdfParser.parse(inputstream, handler, metadata, pcontext);
        }

        // 将解析的内容转换为 XML 文档
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document doc = builder.parse(new ByteArrayInputStream(handler.toString().getBytes()));

        // 创建 XPath 实例
        XPath xpath = XPathFactory.newInstance().newXPath();
        // 使用 XPath 选择特定的节点
        String expression = "/pdf/document_INFO/author";
        String author = (String) xpath.evaluate(expression, doc, XPathConstants.STRING);

        System.out.println("Author: " + author);
    }
}