jQuery+Ajax+Jsp做二级级联

2023-08-05 22:35:16

终于弄懂了这个级联，我去！必须得在博客记下来。

1, JS代码：

 $(document).ready(function(){

     $("#select1").change(function(){

         adjustCountyDropDown();

     });

 });

 function adjustCountyDropDown(){

     var selectedCity= $("#select1").val();

     var county= $("#select2");

     if(selectedCity.length== 0){

         county.attr("disabled", true);

     }

     else{

         county.attr("disabled", false);

 　　　　 //ajax异步

         $.getJSON(

         'http://localhost:8080/TestStu/ajaxSelectCityTest',　　//ajax提交的地址，我这里是servlet文件

         {city: selectedCity},　　//传递的参数，将city这个参数传到ajaxSelectCityTest这个servlet

         function(data){　　//data为返回的数据

             county.empty();        //jQuery清空options

             county.append("<option value=''>Please Choose:</option>");

             $.each(data, function(i, value) {

                 county.append("<option value=" + value.add_county + ">" + value.add_county+ "</option>");

             });

         }

         );

     }

 }

2, 后台Servlet

package test.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import java.sql.Connection;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.ruchi.dao.impl.addDaoImpl;

import com.ruchi.entity.addEntity;

import com.ruchi.util.ConnectionFactory;

import net.sf.json.JSONArray;

public class selectCity extends HttpServlet {

    private static final long serialVersionUID = 7609673947157450475L;

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        doPost(req, resp);

    }

    @Override

    protected void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

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

        response.setHeader("Pragam", "No-cache");

        PrintWriter pw = response.getWriter();

        Connection con = ConnectionFactory.getInstance().makeConnection();

        try {

            List<addEntity> list = new ArrayList<addEntity>();

            // String city= ${Parameter.selectedCity};

            System.out.println("Before : ");

            String city = request.getParameter("city");　　//接收来自前端传来的参数，后面的这个 city 就是第一片JS代码的第18行传来的

            System.out.println("You Just Reciived: "+ city);　　

            addDaoImpl adi = new addDaoImpl();　　//以下为获取后台数据

            list = adi.getCountyByCity(con, city);  //list为获取的所有数据

            JSONArray jsonArray = JSONArray.fromObject(list); //jsonArray为list转为成的JSON数据

            System.out.println(jsonArray.toString());

            pw.print(jsonArray.toString());  //将jsonArray返回到前台 被第一片JS代码的第19行接收

        } catch (SQLException e) {

            e.printStackTrace();

        } finally {

            try {

                con.close();

            } catch (Exception e2) {

                e2.printStackTrace();

            }

            pw.close();　

        }

    }

}

3, JSP页面代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

    <%@page import="java.util.Date"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

    <script src= "http://libs.baidu.com/jquery/1.10.2/jquery.min.js"></script>

    <script src="ajaxTest.js"></script>

    <script src="ajaxSelectCityTest.js"></script>

</head>

<body>

    <center>

        <h2>级联</h2>

        <select id="select1">

            <option value="">Please Choose:</option>

            <option value="xiamen">xiamen</option>

            <option value="changsha">changsha</option>

            <option value="anyang">anyang</option>

            <option value="beijing">beijing</option>

        </select>

        <hr />

        <select id="select2">

            <option value=''>Please Choose:</option>

        </select>

    </center>

</body>

</html>

4, 当然还有一些javaBean代码，操作数据库代码以及web.xml配置文件没有贴出来。

欢迎交流！

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