使用Java/Liferay读取PDF文件并将其再次保存为PDF

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.text.PDFTextStripper;

// 读取PDF文件
PDDocument document = PDDocument.load(new File("input.pdf"));
PDFTextStripper pdfStripper = new PDFTextStripper();
String content = pdfStripper.getText(document);
document.close();

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

// 修改PDF内容
PDDocument document = PDDocument.load(new File("input.pdf"));
PDPage page = document.getPage(0);
PDPageContentStream contentStream = new PDPageContentStream(document, page);
contentStream.beginText();
contentStream.setFont(PDType1Font.HELVETICA_BOLD, 12);
contentStream.newLineAtOffset(100, 700);
contentStream.showText("Hello, World!");
contentStream.endText();
contentStream.close();
document.save("output.pdf");
document.close();

// 保存PDF文件
document.save("output.pdf");
document.close();