java+jquery处理xml数据的方法

import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
public class AjaxXmlServlet extends HttpServlet { 
    private static final long serialVersionUID = 1L; 
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
            throws ServletException, IOException { 
            Integer total = (Integer) req.getSession().getAttribute("total"); 
            int temp = 0; 
            if(total == null ){ 
                temp = 1; 
            }else{ 
                temp = total.intValue() + 1; 
            } 
        req.getSession().setAttribute("total",total.intValue()+temp); 
        try { 
            //1.取参数 
            resp.setContentType("text/xml;charset=GB2312"); 
            PrintWriter out = resp.getWriter(); 
            StringBuilder builder = new StringBuilder(); 
            String old = req.getParameter("name"); 
            //2、检查参数是否有问题 
            String name = old; 
            builder.append("<message>"); 
            if("".equals(old) || old == null){ 
                builder.append("用户名必须输入").append("</message>"); 
                 
            } 
            else     
                 {