javaweb+mysql+c3p0ajax实现三级联动

1.首先要导入jar文件：

c3p0-0.9.5.1.jar
commons-beanutils-1.7.0.jar
commons-collections-3.2.jar
commons-dbutils-1.6.jar
commons-lang-2.4.jar
commons-logging-1.0.4.jar
ezmorph-1.0.3.jar
fastjson-1.1.40.jar
jackson-all-1.7.5.jar
json-lib-2.2.3-jdk15.jar
mchange-commons-java-0.2.10.jar
mysql-connector-java-5.1.30-bin.jar

2.c3p0配置文件

 <?xml version="1.0" encoding="UTF-8"?>

 <c3p0-config>

   <default-config>

     <property name="checkoutTimeout">30000</property>

     <property name="idleConnectionTestPeriod">30</property>

     <property name="initialPoolSize">10</property>

     <property name="maxIdleTime">30</property>

     <property name="maxPoolSize">100</property>

     <property name="minPoolSize">10</property>

     <property name="maxStatements">200</property>

     <!-- 驱动程序 -->

     <property name="driverClass">com.mysql.jdbc.Driver</property>

     <!-- 数据库连接url地址 -->

     <property name="jdbcUrl">jdbc:mysql://localhost:3306/day02</property>

     <!-- 用户名 -->

     <property name="user">****</property>

     <!-- 密码 -->

     <property name="password">****</property>

   </default-config>

 </c3p0-config>

 <!-- <?xml version="1.0" encoding="UTF-8"?>

 <c3p0-config>

   <named-config >

     <property name="acquireIncrement">5</property>

     <property name="initialPoolSize">3</property>

     <property name="minPoolSize">1</property>

     <property name="maxPoolSize">10</property>

     <property name="maxStatements">0</property>

     <property name="user">root</property>

     <property name="password">root</property>

     ?useUnicode=true&characterEncoding=UTF-8

     <property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>

     <property name="driverClass">com.mysql.jdbc.Driver</property>

   </named-config>

 </c3p0-config> -->

3..要建三张表，省市区分别一张

3.写对应的实体类

 public class Province {

     private Integer provinceId;

     private String provinceName;

       .....省略get和set代码

 }

 public class City {

     private Integer cityId;

     private String cityName;

    .....省略get和set方法

 }

 public class Area {

     private Integer areaId;

     private String areaName;

     ...省略set和get方法

 }

4.Util包下的DBManager

 public class DBManager {

         private static ComboPooledDataSource cpds=new ComboPooledDataSource();

         //获取数据库资源

         public static ComboPooledDataSource getDateResource(){

             return cpds;

         }

         //返回连接对象

         public static Connection getConn() throws SQLException{

             return cpds.getConnection();

         }

         //释放资源

         public static void release(Connection conn){

             DbUtils.closeQuietly(conn);

         }

 }

5.dao层

 public class BaseDao{

 private static final QueryRunner runner = new QueryRunner();

     public <T> List<T> getForList(String sql,Class<T> clazz,Object ...args) throws SQLException{

         List<T> list  = null;

         Connection conn = null;

         try {

             conn = DBManager.getConn();

             list = runner.query(conn, sql,new BeanListHandler<T>(clazz),args);

         } catch (Exception e) {

             throw new RuntimeException(e);

         }finally{

             DbUtils.close(conn);

         }

         return list;

     }

6.前台页面 index.jsp

<%

    response.sendRedirect("provinceServlet?method=listProvince");

%>

访问顺序是--->index.jsp----->provinceServlet?method=listProvince------>provice.jsp

7.provice.jsp(包含ajax代码)

 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

 <html>

   <head>

     <title>三级联动页面</title>

     <meta http-equiv="pragma" content="no-cache">

     <meta http-equiv="cache-control" content="no-cache">

     <meta http-equiv="expires" content="0">

     <!--

         1.获取#province，添加change函数

         2.使#province只保留一个option子节点

         3.获取province下来菜单选择的值，若选择的值为“”（请选择省份），此时不需要发送ajax请求

         4.若值不为“”，说明的确是province发生了改变，发送ajax请求

         4.1  url：provinceServlet?method=

         4.2  args:

         5.返回的是一个json数组

         6.遍历，创建<option value="provinceId">provinceName</option>

         并把新创建的option节点加为#city的子节点

      -->

     <script type="text/javascript" src="js/jquery-2.1.4.js"></script>

     <script type="text/javascript">

         $(function(){

         //第二级

              $("#province").change(function(){

                 $("#city option:not(:first)").remove();

                 var province = $(this).val();

                     //alert(province);

                     var url = "provinceServlet?method=listCity";

                     var args = {"provinceId":province/* ,"time":new Date() */};

                     $.getJSON(url, args, function(data){

                     //alert("11111");

                         for(var i = 0;i < data.length; i++){

                             var cityId = data[i].cityId;

                             var cityName = data[i].cityName;

                             $("#city").append("<option value='"+ cityId  + "'>"+cityName+"</option>")

                         }

                     });

                 }

             );

          //第三极

          $("#city").change(function(){

                 $("#area option:not(:first)").remove();

                 var city = $(this).val();

                     //alert(province);

                     var url = "provinceServlet?method=listArea";

                     var args = {"cityId":city,"time":new Date()}; //这里写一个时间戳 每次点击时，时间戳都不一样，浏览器就认为是新的图片，然后就发送请求了。

                     $.getJSON(url, args, function(data){

                     //alert("11111");

                         for(var i = 0;i < data.length; i++){

                             var areaId = data[i].areaId;

                             var areaName = data[i].areaName;

                             $("#area").append("<option value='"+ areaId  + "'>"+areaName+"</option>")

                         }

                     });

                 }

             );

         });

     </script>

   </head>

   <body>

            省份：<select id="province">

             <option>请选择省份</option>

             <c:forEach items="${provinces}" var="province">

                 <option value="${province.provinceId}">${province.provinceName}</option>

             </c:forEach>

             </select>

             城市：<select id="city">

                     <option>请选择城市</option>

                 </select>

             区域：<select id="area">

                     <option>请选择区域</option>

                 </select>

   </body>

 </html>

8.proviceServlet

 package three.controller;

 import java.io.IOException;

 import java.lang.reflect.Method;

 import java.sql.SQLException;

 import java.util.List;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import org.codehaus.jackson.map.ObjectMapper;

 import three.dao.BaseDao;

 import three.domain.Area;

 import three.domain.City;

 import three.domain.Province;

 public class provinceServlet extends HttpServlet {

     public void doGet(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         request.setCharacterEncoding("UTF-8");

         response.setContentType("text/html;charset=UTF-8");

         String methodName = request.getParameter("method");

         try {

             Method method = getClass().getDeclaredMethod(methodName,HttpServletRequest.class,HttpServletResponse.class);

             method.invoke(this, request,response);

         } catch (Exception e) {

             e.printStackTrace();

         } 

     }

     private BaseDao  baseDao = new BaseDao();

     public void listProvince(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, SQLException{

         String sql = "SELECT provinceid,provincename FROM province;";

         List<Province> provinces = baseDao.getForList(sql, Province.class);

         request.setAttribute("provinces", provinces);

         request.getRequestDispatcher("/province.jsp").forward(request, response);

     }

     public void listCity(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, SQLException{

         String provinceId = request.getParameter("provinceId");

         String sql = "select cityid,cityname from city c where c.cityid = ?";

         List<City> cities = baseDao.getForList(sql, City.class, Integer.parseInt(provinceId));

         System.out.println(cities+"===========");

         ObjectMapper mapper = new ObjectMapper();

         String result = mapper.writeValueAsString(cities);

         System.out.println(result);

         response.setContentType("text/javascript");

         response.getWriter().print(result);

     }

 public void listArea(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, SQLException{

     String cityId = request.getParameter("cityId");

     String sql = "select areaid,areaname from area a where a.areaid = ?";

     List<Area> areas = baseDao.getForList(sql, Area.class, Integer.parseInt(cityId));

     System.out.println(areas+"===========");

     ObjectMapper mapper = new ObjectMapper();

     String result = mapper.writeValueAsString(areas);

     System.out.println(result);

     response.setContentType("text/javascript");

     response.getWriter().print(result);

 }

     public void doPost(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         doGet(request,response);

     }

 }

巴特西

javaweb+mysql+c3p0ajax实现三级联动

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