自定义标题的层级关系

/**
     * 增加自定义标题样式。这里用的是stackoverflow的源码
     *
     * @param docxDocument 目标文档
     * @param strStyleId   样式名称
     * @param headingLevel 样式级别
     */
    private static void addCustomHeadingStyle(XWPFDocument docxDocument, String strStyleId, int headingLevel) {

        CTStyle ctStyle = CTStyle.Factory.newInstance();
        ctStyle.setStyleId(strStyleId);

        CTString styleName = CTString.Factory.newInstance();
        styleName.setVal(strStyleId);
        ctStyle.setName(styleName);

        CTDecimalNumber indentNumber = CTDecimalNumber.Factory.newInstance();
        indentNumber.setVal(BigInteger.valueOf(headingLevel));

        // lower number > style is more prominent in the formats bar
        ctStyle.setUiPriority(indentNumber);

        CTOnOff onoffnull = CTOnOff.Factory.newInstance();
        ctStyle.setUnhideWhenUsed(onoffnull);

        // style shows up in the formats bar
        ctStyle.setQFormat(onoffnull);

        // style defines a heading of the given level
        CTPPr ppr = CTPPr.Factory.newInstance();
        ppr.setOutlineLvl(indentNumber);
        ctStyle.setPPr(ppr);

        XWPFStyle style = new XWPFStyle(ctStyle);

        // is a null op if already defined
        XWPFStyles styles = docxDocument.createStyles();

        style.setType(STStyleType.PARAGRAPH);
        styles.addStyle(style);

    }
**使用方式**
//创建文档对象
        XWPFDocument document = new XWPFDocument();
        addCustomHeadingStyle(document, "标题 1", 1);
        addCustomHeadingStyle(document, "标题 2", 2);
        addCustomHeadingStyle(document, "标题 3", 3);