使用pdfbox合并PDF

<dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>pdfbox</artifactId>
            <version>2.0.14</version>
        </dependency>

public static File mergeDocuments(File files, String filePath) throws IOException {
        PDFMergerUtility pdf = new PDFMergerUtility();
        for (File f : files.listFiles()) {
            if (f.getName().contains("汇总")) {
                continue;
            }
            if (f.exists() && f.isFile()) {
                pdf.addSource(f);
            }
        }
        // 设置合并生成pdf文件名称
        pdf.setDestinationFileName(filePath);
        // 开始合并pdf
        pdf.mergeDocuments(MemoryUsageSetting.setupMainMemoryOnly());
        File file = new File(filePath);
        //加载PDF
        PDDocument document = PDDocument.load(file);
        AccessPermission accessPermission = new AccessPermission();
        accessPermission.setCanPrint(true);
        accessPermission.setCanModify(false);
        accessPermission.setCanExtractContent(false);
        StandardProtectionPolicy spp  = new StandardProtectionPolicy("编辑pdf需要密码",null, accessPermission);
        spp.setEncryptionKeyLength(256);
        spp.setPermissions(accessPermission);
        document.protect(spp);
        document.save(filePath);
        document.close();
        return file;
    }

files是已经生成好PDF的文件夹，filePath是合并后生成PDF路径