首先来看工程结构图：
项目所需要的包，如下所示：
JSP代码：
1 <%@ page language="java" import="java.util.*" pageEncoding="GBK"%> 2 <% 3 String path = request.getContextPath(); 4 String basePath = request.getScheme() + "://" 5 + request.getServerName() + ":" + request.getServerPort() 6 + path + "/"; 7 System.out.println("basePath="+basePath); 8 %> 9 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">10 <html>11 <head>12 <title>JsonCase</title>13 <script type="text/javascript" src='/images/loading.gif' data-original="<%=basePath %>js/jquery-1.7.2.min.js"></script>14 <script type="text/javascript">15 $(function($) {16 $("#record").append("当前测试页面完成加载。<br/>");17 });18 function getFirstFloorValue(element) {19 $("#record").append("<br/>获取到信息：您将要取得第一级选项信息……");20 $("#record").append("<br/>正在使用ajax为您获取数据，您可以继续停留在页面并进行其他操作。");21 $.ajax({22 url : 'ValueGetController',23 type : 'post',24 data : 'action=GetFirstFloorValue',25 datatype : 'json',26 success : function(data) {27 $("#record").append("<br/>操作成功，正在为您准备数据……");28 $(element).empty();29 $("#record").append("<br/>清除原始数据成功！");30 var ops = $.parseJSON(data);31 $("#record").append("<br/>即时数据准备成功！");32 for ( var i = 0; i < ops.length; i++)33 $(element).append(34 "<option value=\"" + ops[i] + "\">" + ops[i]35 + "</option>");36 $("#record").append("<br/>更新列表成功！<br/>");37 }38 });39 40 41 }42 </script>43 </head>44 45 <body>46 <div>47 48 <select id="select1" onfocus=getFirstFloorValue(this)>49 <option value="1">点击取值</option>50 </select>51 </div>52 <dir>53 <h3>记录信息：</h3>54 <span id="record"></span>55 </dir>56 </body>57 </html>
JAVA servlet代码：
1 package servlet; 2 3 import java.io.IOException; 4 import java.io.PrintWriter; 5 6 import javax.servlet.ServletException; 7 import javax.servlet.http.HttpServlet; 8 import javax.servlet.http.HttpServletRequest; 9 import javax.servlet.http.HttpServletResponse;10 import net.sf.json.JSONArray;11 12 public class ValueGetController extends HttpServlet {13 14 private static final long serialVersionUID = -1293610555518403602L;15 16 17 /**18 * Constructor of the object.19 */20 public ValueGetController() {21 super();22 }23 24 /**25 * Destruction of the servlet. <br>26 */27 public void destroy() {28 super.destroy(); // Just puts "destroy" string in log29 // Put your code here30 }31 32 /**33 * The doGet method of the servlet. <br>34 *35 * This method is called when a form has its tag value method equals to get.36 * 37 * @param request the request send by the client to the server38 * @param response the response send by the server to the client39 * @throws ServletException if an error occurred40 * @throws IOException if an error occurred41 */42 public void doGet(HttpServletRequest request, HttpServletResponse response)43 throws ServletException, IOException {44 45 doPost(request, response);46 47 48 }49 50 /**51 * The doPost method of the servlet. <br>52 *53 * This method is called when a form has its tag value method equals to post.54 * 55 * @param request the request send by the client to the server56 * @param response the response send by the server to the client57 * @throws ServletException if an error occurred58 * @throws IOException if an error occurred59 */60 public void doPost(HttpServletRequest request, HttpServletResponse response)61 throws ServletException, IOException {62 63 request.setCharacterEncoding("GBK");64 response.setContentType("text/html;charset=gbk");65 PrintWriter out = response.getWriter();66 String action = request.getParameter("action");67 System.out.println("action"+action);68 if (action.equals("GetFirstFloorValue")) {69 String[] str = GetFirstFloorValue();70 JSONArray ja = JSONArray.fromObject(str);71 String json = ja.toString();72 out.print(json);73 System.out.println(json);74 out.flush();75 out.close();76 return;77 }78 out.flush();79 out.close();80 }81 82 private String[] GetFirstFloorValue() {83 String[] str = new String[4];84 str[0] = "test1";85 str[1] = "test2";86 str[2] = "test3";87 str[3] = "test4";88 return str;89 90 }91 92 93 94 }关于servlet的web.
1 <??> 2 <web-app version="2.5" 3 ="http://java.sun.com/ 4 ="http://www.w3.org/2001/ 5 xsi:schemaLocation="http://java.sun.com/ 6 http://java.sun.com/> 7 <servlet> 8 <description>This is the description of my J2EE component</description> 9 <display-name>This is the display name of my J2EE component</display-name>10 <servlet-name>ValueGetController</servlet-name>11 <servlet-class>servlet.ValueGetController</servlet-class>12 </servlet>13 14 <servlet-mapping>15 <servlet-name>ValueGetController</servlet-name>16 <url-pattern>/ValueGetController</url-pattern>17 </servlet-mapping>18 19 20 21 <welcome-file-list>22 <welcome-file>index.jsp</welcome-file>23 </welcome-file-list>24 </web-app>
原标题：Jquery+ajax+JAVA(servlet)实现下拉菜单异步取值
关键词：JAVA
我知道了 