dynamicLists.html
例子来源：《Ajax 基础教程》 金灵 等译 这本书非常不错dynamicLists.html
<html><head><title>Dynamically Filling Lists</title><script type="text/javascript">var xmlHttp;function createXMLHttpRequest() {if (window.ActiveXObject) {xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");}else if (window.XMLHttpRequest) {xmlHttp = new XMLHttpRequest();}}function refreshModelList() {var make = document.getElementById("make").value;var modelYear = document.getElementById("modelYear").value;if (make == "" || modelYear == "") {clearModelsList();return;}var url = "RefreshModelList?"+ createQueryString(make, modelYear) + "&ts=" + new Date().getTime();createXMLHttpRequest();xmlHttp.onreadystatechange = handleStateChange;xmlHttp.open("GET", url, true);xmlHttp.send(null);}function createQueryString(make, modelYear) {var queryString = "make=" + make + "&modelYear=" + modelYear;return queryString;}function handleStateChange() {if (xmlHttp.readyState == 4) {if (xmlHttp.status == 200) {updateModelsList();}}}function updateModelsList() {clearModelsList();var models = document.getElementById("models");var results = xmlHttp.responseXML.getElementsByTagName("model");var option = null;for (var i = 0; i < results.length; i++) {option = document.createElement("option");option.appendChild(document.createTextNode(results.firstChild.nodeValue));models.appendChild(option);}}function clearModelsList() {var models = document.getElementById("models");while (models.childNodes.length > 0) {models.removeChild(models.childNodes);}}</script></head><body><h1>Select Model Year and Make</h1><form action="#"><span style="font-weight:bold;">Model Year:</span><select id="modelYear" onchange="refreshModelList();"><option value="">Select One</option><option value="2006">2006</option><option value="1995">1995</option><option value="1985">1985</option><option value="1970">1970</option></select><br/><br/><span style="font-weight:bold;">Make:</span><select id="make" onchange="refreshModelList();"><option value="">Select One</option><option value="Chevrolet">Chevrolet</option><option value="Dodge">Dodge</option><option value="Pontiac">Pontiac</option></select><br/><br/><span style="font-weight:bold;">Models:</span><br/><select id="models" size="6" style="width:300px;"></select></form></body></html>
RefreshModelListServlet.java
package ajaxbook.chap4;import java.io.IOException;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class RefreshModelListServlet extends HttpServlet {private static List availableModels = new ArrayList();protected void processRequest(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");int modelYear = Integer.parseInt(request.getParameter("modelYear"));String make = request.getParameter("make");StringBuffer results = new StringBuffer("<models>");MakeModelYear availableModel = null;for (Iterator it = availableModels.iterator(); it.hasNext();) {availableModel = (MakeModelYear) it.next();if (availableModel.modelYear == modelYear) {if (availableModel.make.equals(make)) {results.append("<model>");results.append(availableModel.model);results.append("</model>");}}}results.append("</models>");response.setContentType("text/xml");response.getWriter().write(results.toString());}protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {processRequest(request, response);}public void init() throws ServletException {availableModels.add(new MakeModelYear(2006, "Dodge", "Charger1"));availableModels.add(new MakeModelYear(1995, "Dodge", "Charger2"));availableModels.add(new MakeModelYear(1985, "Dodge", "Charger3"));availableModels.add(new MakeModelYear(1970, "Dodge", "Charger4"));availableModels.add(new MakeModelYear(2006, "Dodge", "Charger5"));availableModels.add(new MakeModelYear(2006, "Dodge", "Charger6"));availableModels.add(new MakeModelYear(2006, "Dodge", "Charger7"));availableModels.add(new MakeModelYear(2006, "Dodge", "Charger8"));}private static class MakeModelYear {private int modelYear;private String make;private String model;public MakeModelYear(int modelYear, String make, String model) {this.modelYear = modelYear;this.make = make;this.model = model;}}}
页:
[1]