dom4j回车换行符（给群中朋友需要解决的基础写的乱看看就行）

public class Main {    public Main() {    }    public static void main(String[] args) {        Main user = new Main();        user.newXML();    }    public void newXML(){        Document doc = DocumentHelper.createDocument();         Element users = doc.addElement("users");         doc.setRootElement(users);        doc.getRootElement().addAttribute(QName.get("space", Namespace.XML_NAMESPACE),                  "preserve");//就是这里        Element user = users.addElement("user");         user.addAttribute("id","1");        Element username = user.addElement("username");        username.setText("yy");        Element password = user.addElement("password");         password.setText("1234\r\n5678"); //就是这里        OutputFormat format = OutputFormat.createPrettyPrint();         format.setEncoding("GB2312");         try {            XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(new File("a.xml")),format);            xmlWriter.write(users);            xmlWriter.close();        } catch (Exception e) {            e.printStackTrace();        }    }  }