点击这里
  

servlet：

public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        System.out.println("Hello AJAX!");        response.getWriter().print("Hello AJAX!!!");    }        public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html;charset=utf-8");        request.setCharacterEncoding("UTF-8");                String username = request.getParameter("username");//获取请求参数        System.out.println("(POST：) Hello AJAX!" + username);        response.getWriter().print("(POST：) Hello AJAX!!!" + username);    }

public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        request.setCharacterEncoding("utf-8");        response.setContentType("text/html;charset=utf-8");                /*         * 1. 获取参数username         * 2. 判断是否为itcast         *   3. 如果是：响应1         *   4. 如果不是：响应0         */        String username = request.getParameter("username");        if(username.equalsIgnoreCase("itcast")) {            response.getWriter().print("1");        } else {            response.getWriter().print("0");        }    }

1 52   53   54   55 
演示用户名是否被注册
56 
     
      57 用户名：
      
      
      
58 密　码：
      
      
59 
      60 
     
61   

4:xml显示到jsp

      点击这里
  

1 public class BServlet extends HttpServlet { 2     public void doGet(HttpServletRequest request, HttpServletResponse response) 3             throws ServletException, IOException { 4         String xml = "
     
      " + 5             "
      
       " + 6             "
       
        zhangSan
       " + 7             "
       
        18
       " +  8             "
       
        male
       " + 9             "
      " +10             "
     ";11         12         response.setContentType("text/xml;charset=utf-8");13         response.getWriter().print(xml);14     }15 }

 

联动：

cityservlet：

1 public class CityServlet extends HttpServlet { 2  3     public void doPost(HttpServletRequest request, HttpServletResponse response) 4             throws ServletException, IOException { 5         request.setCharacterEncoding("utf-8"); 6         response.setContentType("text/xml;charset=utf-8");//注意：发送xml这里要修改！！！ 7          8         /* 9          * 获取省份名称，加载该省对应的
     
      元素！10          * 把元素转换成字符串发送给客户端11          */12         /*13          * 1. 获取省份的名称14          * 2. 使用省份名称查找到对应的
      
       元素15          * 3. 把
       
        元素转换成字符串，发送！16          */17         try {18             /*19              * 得到Document20              */21             SAXReader reader = new SAXReader();22             InputStream input = this.getClass().getResourceAsStream("/china.xml");23             Document doc = reader.read(input);24             25             /*26              * 获取参数27              */28             String pname = request.getParameter("pname");//获取省份名称29             Element proEle = (Element) doc.selectSingleNode("//province[@name='" + pname + "']");30             String xmlStr = proEle.asXML();//把元素转换成字符串31             response.getWriter().print(xmlStr);32         } catch(Exception e) {33             throw new RuntimeException(e);34         }35     }
       
      
     

provinceservlet：

1 public class ProvinceServlet extends HttpServlet { 2  3     public void doGet(HttpServletRequest request, HttpServletResponse response) 4             throws ServletException, IOException { 5         response.setContentType("text/html;charset=utf-8"); 6         /* 7          * 响应所有省份名称，使用逗号分隔！ 8          */ 9         /*10          * 1. Document对象11          *   * 创建解析器对象12          *   * 调用解析器的读方法，传递一个流对象，得到Document13          */14         try {15             SAXReader reader = new SAXReader();16             InputStream input = this.getClass().getResourceAsStream("/china.xml");17             Document doc = reader.read(input);18             19             /*20              * 查询所有province的name属性，得到一堆的属性对象21              * 循环遍历，把所有的属性值连接成一个字符串，发送给客户端22              */23             List
     
       arrList = doc.selectNodes("//province/@name");24             StringBuilder sb = new StringBuilder();25             for(int i = 0; i < arrList.size(); i++) {26                 sb.append(arrList.get(i).getValue());//把每个属性的值存放到sb中。27                 if(i < arrList.size() - 1) {28                     sb.append(",");29                 }30             }31             response.getWriter().print(sb);32         } catch(Exception e) {33             throw new RuntimeException(e);34         }35     }
     

jsp：

1 106   107   108   109 
省市联动
110 111   ===请选择省===112 113 　　　114 115   ===请选择市===116 117