合并PDF

public static List<File> mergePdf(List<String> filePath) throws Exception {
        List<File> list = new ArrayList<File>();

        long m10 = 10 * 1024 * 1024;
        long legth = 0;
        File file = null;
        PDFMergerUtility mergePdf = new PDFMergerUtility();
        for (int i = 0; i < filePath.size(); i++) {
            file = new File(filePath.get(i));
            if (file != null) {
                if (i == (filePath.size() - 1)) {
                    mergePdf.addSource(file);
                    String mergePdfPath = file.getParentFile() + "\" + (new Date().getTime()) + ".pdf";
                    mergePdf.setDestinationFileName(mergePdfPath);
                    mergePdf.mergeDocuments();
                    list.add(new File(mergePdfPath));
                }
                if (file.length() >= m10) {// 单个文件大于10M,不合并
                    mergePdf = new PDFMergerUtility();
                    mergePdf.addSource(file);
                    String mergePdfPath = file.getParentFile() + "\" + (new Date().getTime()) + ".pdf";
                    mergePdf.setDestinationFileName(mergePdfPath);
                    mergePdf.mergeDocuments();
                    list.add(new File(mergePdfPath));
                    continue;
                }
                if ((file.length() + legth) >= m10) {// 合并pdf
                    String mergePdfPath = file.getParentFile() + "\" + (new Date().getTime()) + ".pdf";
                    mergePdf.setDestinationFileName(mergePdfPath);
                    mergePdf.mergeDocuments();
                    list.add(new File(mergePdfPath));

                    legth = file.length();
                    mergePdf = new PDFMergerUtility();
                    mergePdf.addSource(file);
                } else {
                    legth += file.length();
                    mergePdf.addSource(file);
                }
            }
        }
        return list;
    }