jQuery+jsp实现省市县三级联动效果(附源码)_jquery

public class GetDropdownDataServlet extends HttpServlet {
 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws IOException, ServletException {
  doPost(request, response);
 }
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws IOException, ServletException {
  String parentId = request.getParameter("parentId");
  if (parentId == null || parentId == "") {
   parentId = "0";
  }
  Connection conn = null;
  String json = "";
  try {
   Class.forName("com.mysql.jdbc.Driver");
   conn = DriverManager.getConnection("jdbc:mysql://localhost/dropdown",
     "root", "root");
   Statement stat = conn.createStatement();
   ResultSet rs = stat
     .executeQuery("select region_id,region_name from region where parent_id = "
       + parentId);
   ArrayList rsList = new ArrayList();
   Map map = null;
   while (rs.next()) {
    map = new HashMap();
    map.put("id", rs.getInt(1));
    map.put("name", rs.getString(2));
    rsList.add(map);
   }
   rs = null;
   Gson gson = new Gson();
   json = gson.toJson(rsList);
   System.out.println("json=" + json);
  } catch (ClassNotFoundException e) {
   e.printStackTrace();
  } catch (SQLException e) {
   e.printStackTrace();
  } finally {
   if (conn != null) {
    try {
     conn.close();
    } catch (SQLException e) {
     e.printStackTrace();
    }
   }
  }
  response.setCharacterEncoding("UTF-8");
  response.getWriter().print(json);
 }
}