dom4j,标签属性添加不上问题

Question

1.问题是:xmlns属性为什么没有加进去呢？
直接放代码（结果图在后面）

 public static void main(String[] args){
        XMLWriter writer=null;
        FileOutputStream out=null;
        try {
            Document doc = DocumentHelper.createDocument();
            Element Cole = doc.addElement("Cole");
            Cole.addAttribute("xmlns","http://www.gzrst.gov.cn/DA");
            Cole.addAttribute("xmlns:xsi","http://www.w3.org/2001/XMLSchema-instance");
            Cole.addAttribute("xsi:schemaLocation","http://www.gzrst.gov.cn/DA SIP.xsd");

            out = new FileOutputStream("d:/test2.xml");
            OutputFormat format = OutputFormat.createPrettyPrint();
            format.setEncoding("utf-8");
            writer = new XMLWriter(out,format);
            writer.write(doc);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (writer != null) {
                try {
                    writer.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }

2.结果:

Answer 1

改一句就可以了：

 Document doc = DocumentHelper.createDocument();
            Element Cole = doc.addElement("Cole");

            Namespace namespace = Namespace.get("http://www.gzrst.gov.cn/DA");

//            Cole.addAttribute("xmlns","http://www.gzrst.gov.cn/DA");
            Cole.add(namespace);
            Cole.addAttribute("xmlns:xsi","http://www.w3.org/2001/XMLSchema-instance");
            Cole.addAttribute("xsi:schemaLocation","http://www.gzrst.gov.cn/DA SIP.xsd");