<!-- https://mvnrepository.com/artifact/org.apache.pdfbox/pdfbox -->

        <dependency>

            <groupId>org.apache.pdfbox</groupId>

            <artifactId>pdfbox</artifactId>

            <version>3.0.2</version>

        </dependency>

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {

        PDFMergerUtility mergePdf = new PDFMergerUtility();

        File file0 = new File("E:\\work_other\\third\\pdfmerge\\doc\\首页.pdf");

        File file1 = new File("E:\\work_other\\third\\pdfmerge\\doc\\流通报告样本.pdf");

        File file2 = new File("E:\\work_other\\third\\pdfmerge\\doc\\末页.pdf");

        try {

            PDFMergerUtility pdfMerger = new PDFMergerUtility();

            pdfMerger.addSource(file0);

            pdfMerger.addSource(file1);

            pdfMerger.addSource(file2);       

            pdfMerger.setDestinationFileName("E:\\work_other\\third\\pdfmerge\\doc\\test.pdf");

            // 合并文件

            pdfMerger.mergeDocuments(null);

        } catch (Exception ex) {

            Logger.getLogger(PdfMerge.class.getName()).log(Level.SEVERE, null, ex);

        }       

    } 

致敬 https://blog.csdn.net/YongHu00001/article/details/125341778