apache.poi设置word页眉页脚

1、通过几种页眉页脚跟奇偶不同设置实现，word导出差异化需求。
2、页脚也相同，如果显示每页页码，需要设置几种不同的页脚：FIRST（首页），DEFAULT（默认），EVEN（偶数）

            XWPFDocument docx = new XWPFDocument();
            XWPFHeaderFooterPolicy headerFooterPolicy = docx.getHeaderFooterPolicy();
            if (headerFooterPolicy == null) headerFooterPolicy = docx.createHeaderFooterPolicy();
            String sealType = "";
            sealType = paperTemplate.getPtSealLineType().toLowerCase();
            switch (sealType) {
                case "once":
                    //首页
                   docx.createHeader(HeaderFooterType.FIRST);
                    break;
                case "default":
                    //每页
                    headerFooterPolicy.createHeader(STHdrFtr.DEFAULT);
                    break;
                case "odd":
                    //奇数页
                    docx.setEvenAndOddHeadings(true);
                    headerFooterPolicy.createHeader(STHdrFtr.DEFAULT);
                    headerFooterPolicy.createHeader(STHdrFtr.EVEN);
                    break;
                case "even":
                    //偶数页
                    docx.setEvenAndOddHeadings(true);
                    headerFooterPolicy.createHeader(STHdrFtr.DEFAULT);
                    headerFooterPolicy.createHeader(STHdrFtr.EVEN);
                    break;

            }