java实现的二级联动菜单效果

<%@ page language="java" pageEncoding="UTF-8"%>

  
    
    
  
  
    

      
        

          

            

              二级联动示例
            
          
          

            

              
                
                
                  请选择
                
                
                  北京
                
                
                  天津
                
                
                  山东
                
              
              
                
                
                  请选择
                
              
            
          
          

            

            
          

        
      
    
  

package com;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/***
 *
 * @author zdw
 *
 */
public class SelectServlet extends HttpServlet
{
  private static final long serialVersiOnUID= 1L;
  public SelectServlet()
  {
    super();
  }
  public void destroy()
  {
    super.destroy();
  }
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException
  {
//    response.setCharacterEncoding("GBK");
    response.setContentType("text/xml");
    response.setHeader("Cache-Control", "no-cache");
    request.setCharacterEncoding("GBK");
    response.setCharacterEncoding("UTF-8");
    String targetId = request.getParameter("id").toString();
    System.out.println(targetId);
    // 获得请求中参数为id的值
    String xml_start = "";
    String xml_end = "";
    String xml = "";
    if (targetId.equalsIgnoreCase("0"))
    {
      xml = "0请选择";
    } else if (targetId.equalsIgnoreCase("1"))
    {
      xml = "1昌平";
      xml += "2丰台";
      xml += "3海淀";
      xml += "4朝阳";
    } else if (targetId.equalsIgnoreCase("2"))
    {
      xml = "1塘沽区";
      xml += "2汉沽区";
      xml += "3大港区";
      xml += "4东丽区";
    } else
    {// 如果是3,则返回下面的字符
      xml = "1济南";
      xml += "2青岛";
      xml += "3淄博";
      xml += "4枣庄";
    }
    String last_xml = xml_start + xml + xml_end;
    response.getWriter().write(last_xml);
  }
  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException
  {
    doGet(request, response);
  }
  public void init() throws ServletException
  {
  }
}

<&＃63;xml version="1.0" encoding="UTF-8"&＃63;>

  
    SelectServlet
    com.SelectServlet
  
  
    SelectServlet
    /select
  
  
    index.jsp