claude-code/skills/pdf/SKILL.md

name	description
pdf	Process PDF files - extract text, create PDFs, merge documents. Use when user asks to read PDF, create PDF, or work with PDF files.

PDF Processing Skill

You now have expertise in PDF manipulation. Follow these workflows:

Reading PDFs

Option 1: Quick text extraction (preferred)

# Using pdftotext (poppler-utils)
pdftotext input.pdf -  # Output to stdout
pdftotext input.pdf output.txt  # Output to file

Option 2: Page-by-page with metadata (Apache PDFBox)

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.text.PDFTextStripper;
import java.io.File;

PDDocument doc = PDDocument.load(new File("input.pdf"));
System.out.println("Pages: " + doc.getNumberOfPages());
System.out.println("Metadata: " + doc.getDocumentInformation().getTitle());

PDFTextStripper stripper = new PDFTextStripper();
for (int i = 1; i <= doc.getNumberOfPages(); i++) {
    stripper.setStartPage(i);
    stripper.setEndPage(i);
    String text = stripper.getText(doc);
    System.out.println("--- Page " + i + " ---");
    System.out.println(text);
}
doc.close();

Creating PDFs

Option 1: From Markdown (recommended)

# Using pandoc
pandoc input.md -o output.pdf

# With custom styling
pandoc input.md -o output.pdf --pdf-engine=xelatex -V geometry:margin=1in

Option 2: Programmatically (Apache PDFBox)

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.font.PDType1Font;

PDDocument doc = new PDDocument();
PDPage page = new PDPage();
doc.addPage(page);

try (PDPageContentStream content = new PDPageContentStream(doc, page)) {
    content.beginText();
    content.setFont(PDType1Font.HELVETICA, 12);
    content.newLineAtOffset(100, 750);
    content.showText("Hello, PDF!");
    content.endText();
}
doc.save("output.pdf");
doc.close();

Option 3: From HTML (OpenHTMLToPDF)

import com.openhtmltopdf.pdfboxout.PdfRendererBuilder;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;

String html = Files.readString(Path.of("input.html"));
try (OutputStream os = new FileOutputStream("output.pdf")) {
    PdfRendererBuilder builder = new PdfRendererBuilder();
    builder.withHtmlContent(html, new File("input.html").toURI().toString());
    builder.toStream(os);
    builder.run();
}

Merging PDFs

import org.apache.pdfbox.multipdf.PDFMergerUtility;
import java.io.File;

PDFMergerUtility merger = new PDFMergerUtility();
merger.addSource(new File("file1.pdf"));
merger.addSource(new File("file2.pdf"));
merger.addSource(new File("file3.pdf"));
merger.setDestinationFileName("merged.pdf");
merger.mergeDocuments(null);

Splitting PDFs

import org.apache.pdfbox.multipdf.Splitter;
import org.apache.pdfbox.pdmodel.PDDocument;
import java.io.File;
import java.util.List;

PDDocument doc = PDDocument.load(new File("input.pdf"));
Splitter splitter = new Splitter();
splitter.setSplitAtPage(1); // 每页拆分为一个文件
List<PDDocument> pages = splitter.split(doc);

for (int i = 0; i < pages.size(); i++) {
    pages.get(i).save("page_" + (i + 1) + ".pdf");
    pages.get(i).close();
}
doc.close();

Key Libraries

Task	Library	Maven Dependency
Read/Write/Merge/Split	Apache PDFBox	org.apache.pdfbox:pdfbox:3.0.x
Create from HTML	OpenHTMLToPDF	com.openhtmltopdf:openhtmltopdf-pdfbox:1.0.x
Advanced layout	iText	com.itextpdf:itext7-core:8.0.x
Text extraction	pdftotext	brew install poppler / apt install poppler-utils

Best Practices

1. Always check if tools are installed before using them
2. Handle encoding issues - PDFs may contain various character encodings
3. Large PDFs: Process page by page to avoid memory issues; use try-with-resources 确保资源释放
4. OCR for scanned PDFs: Use Tesseract4J (net.sourceforge.tess4j:tess4j) if text extraction returns empty