XMLHttpRequest对象提供了两个可以用来访问服务器响应的属性。第一个属性responseText将响应提供为一个串，第二个属性 responseXML将响应提供为一个XML对象。一些简单的用例就很适合按简单文本来获取响应，如将响应显示在警告框中，或者响应只是指示成功还是失 败的词
前面<ajax小结>中的例子是从XMLHttpRequest对象获取服务器响应，并使用XMLHttpRequest对象的responseText属性将响应获取为文本。
这次我们来使用XMLHttpRequest对象的responseXML属性，将结果获取为XML文档.这样一来，我们就可以使用W3C DOM方法来遍历XML文档。(前面文章或多或少讲过些DOM,在此不重复)
OK,下面来看例子.
首先还是一段XML文档代码(parseXML.xml)如下:
parseXML.xml如下：
<?xml version="1.0" encoding="UTF-8"?> <states> <north> <state>Minnesota</state> <state>Iowa</state> <state>North Dakota</state> </north> <south> <state>Texas</state> <state>Oklahoma</state> <state>Louisiana</state> </south> <east> <state>New York</state> <state>North Carolina</state> <state>Massachusetts</state> </east> <west> <state>California</state> <state>Oregon</state> <state>Nevada</state> </west> </states>
MyJsp.jsp如下：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"https://www.jb51.net/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="https://www.jb51.net/<%=basePath%>"> <title>My JSP 'MyJsp.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link type="text/css" href="https://www.jb51.net/styles.css"> --> </head> <script type="text/javascript"> var flg=false; var requestType = ""; //得到XMLHttpRequest对象 function newXMLHttpRequest() { var xmlreq = false; if (window.XMLHttpRequest) { xmlreq = new XMLHttpRequest(); } else if (window.ActiveXObject) { try { xmlreq = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e1) { try { xmlreq = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e2) {} } } return xmlreq; } function startRequest(requestedList){ requestType=requestedList; flg=newXMLHttpRequest(); //当XMLHttpRequest对象在请求过程中间状态改变的时候 //回来调用handleStateChange方法 flg.onreadystatechange = handleStateChange; flg.open("GET", "parseXML.xml", true); flg.send(null); } //处理函数 function handleStateChange(){ if(flg.readyState==4){ if(flg.status==200){ if(requestType=="north"){ listNorthStates(); }else if(requestType=="all"){ listAllStates(); }if(requestType=="south"){ listSouthStates(); } } } } //用于显示NorthStates方法 function listNorthStates(){ var xmlDoc=flg.responseXML; var northNode=xmlDoc.getElementsByTagName("north")[0]; var northStates=northNode.getElementsByTagName("state"); outputList("North States",northStates); } //用于显示SouthStates方法 function listSouthStates(){ var xmlDoc=flg.responseXML; var SouthNode=xmlDoc.getElementsByTagName("south")[0]; var SouthStates=SouthNode.getElementsByTagName("state"); outputList("South States",SouthStates); } //用于显示AllStates方法 function listAllStates(){ var xmlDoc=flg.responseXML; var allStates=xmlDoc.getElementsByTagName("state"); outputList("All States in Document", allStates); } //输出元素并显示于提示框中 function outputList(title,states){ var out=title; var currState=null; for(var i=0;i<states.length;i++){ currState=states; out=out+"\n-"+currState.childNodes[0].nodeValue; } alert(out); } </script> <body> <form action="#"> <input type="button" value="View All Listed States"/><br> <input type="button" value="View All Listed Northern States"/><br> <input type="button" value="View All Listed Southern States"/> </form> </body> </html>