ajax技术
上面是index.jsp页面，如果要使用标签那么就要导入jstl的包，然后采用绝对路径来访问其他的界面。
下面是ajaxXml.jsp页面
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <!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>ajax处理xml数据演示示例</title> <script type="text/javascript"> function send1(){ alert("返回的信息是:"); var name = document.getElementById("nm").value; //1创建ajax对象 var xhr=null; if(window.XMLHttpRequest){//高版本IE,火狐等 xhr = new XMLHttpRequest(); }else{//低版本IE xhr = new ActiveXObject("Microft.XMLHttp"); } //2请求地址 var url = "<c:url value='/XmlServlet?name="+name+"'/>"; //get方式，请求参数在地址栏中 //3设置访问方式 xhr.open("GET", url, true); //4设置访问成功返回后的操作 xhr.onreadystatechange = function(){ if(xhr.readyState==4){ if(xhr.status==200){ var txt = xhr.responseText; alert("返回的信息是:"+txt); } } }; //5发送 xhr.send(null); } function send2(){ //1创建ajax对象 var xhr=null; if(window.XMLHttpRequest){//高版本IE,火狐等 xhr = new XMLHttpRequest(); }else{//低版本IE xhr = new ActiveXObject("Microft.XMLHttp"); } //2请求地址 var url = "<c:url value='/XmlServlet'/>"; //post方式，请求参数在 send()方法的实参 //3设置访问方式 xhr.open("POST", url, true); //4设置访问成功返回后的操作 xhr.onreadystatechange = function(){ if(xhr.readyState==4){ if(xhr.status==200){ //接收后台发过来的xml格式文档(字符串) var xmlDomObj = xhr.responseXML;//★★★这种方式接收到的是一个 XmlDomObject //alert(xmlDomObj); //object //从XmlDom对象中解析出数据 var users = xmlDomObj.getElementsByTagName("user");//array for(var i=0; i<users.length; i++){ var id = users[i].getAttribute("id"); var name = users[i].childNodes[0].firstChild.data; var age = users[i].childNodes[1].firstChild.data; alert(id+", "+name+", "+age);//这个地方的数据是通过获取后台数据进行显示 的； } } } }; ///////////////////////1111///////////////////////// //向后台发送XML格式的字符串 var name = document.getElementById("nm").value; var age = document.getElementById("ag").value; var xml ="<user><name>"+name+"</name><age>"+age+"</age></user>"; xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded" ); //5发送 xhr.send(xml); } </script> </head> <body> Name:<input type="text" id="nm" name="name" /><br/> Age:<input type="text" id="ag" name="age" /> <br/> <!-- send1()和XmlServlet的doGet()不是我们今天的新知识，只是复习，便于我们过渡到新知识点 --> <input type="button" onclick="send1();" value="get发送ajax"><br/><br/> <input type="button" onclick="send2();" value="post-ajax发送XML数据"> </body> </html>
下面是servlet层,下面是XmlServlet.servlet
package cn.hncu.servlet;
import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.StringReader; import java.util.ArrayList; import java.util.List; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.dom4j.Document; import org.dom4j.DocumentException; import org.dom4j.Element; import org.dom4j.io.SAXReader; import cn.hncu.domain.User; @WebServlet("/XmlServlet") public class XmlServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("get...."); String name = request.getParameter("name"); // name = new String(name.getBytes("ISO8859-1"),"utf-8"); // System.out.println("name:"+name); // response.setContentType("text/html;charset=utf-8"); response.getWriter().println("XmlServlet Answer 1223: "+name); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); InputStream in = request.getInputStream(); BufferedReader br = new BufferedReader( new InputStreamReader(in)); String line = null; String xml=""; while((line=br.readLine())!=null){ xml = xml + line; } System.out.println(xml); //上面只是把前端发过来的 符合xml格式的字符串(文档)读取出来 //下面用dom4j来解析出 xml格式的文档 SAXReader sax = new SAXReader(); try { Document dom = sax.read( new StringReader( xml ) ); Element root = dom.getRootElement(); String name = root.elementText("name"); String age = root.elementText("age"); System.out.println("后台解析xml文档的结果:"+name+","+age); } catch (DocumentException e) { e.printStackTrace(); } ////////////////////////222///////////////////////// ////以下演示后台向前端发送xml格式的数据 //按理应该调用service、dao层并从数据库中把数据读取出来，这里模拟了... List<User> users = new ArrayList<User>(); users.add( new User("U001","Jack",22)); users.add( new User("U010","张三",12)); users.add( new User("U002","Rose",23)); //<users> <user id="U001"><name>Jack</name><age>22</age> </user> <user id="U010"><name>张三</name><age>12</age></user> ... </users> String res = "<users>"; for(User u:users){ res += "<user id=\""+u.getId()+"\"><name>"+u.getName()+"</name><age>"+u.getAge()+"</age></user>"; } res +="</users>"; //发给前端 response.setContentType("text/xml;charset=utf-8");//★★★ response.getWriter().print(res); } }
//发给前端
response.setContentType("text/xml;charset=utf-8");//★★★
response.getWriter().print(res);
//在前端页面获取后台发过来的信息
var xmlDomObj = xhr.responseXML;//★★★这种方式接收到的是一个 XmlDomObject
//alert(xmlDomObj); //object
//从XmlDom对象中解析出数据
var users = xmlDomObj.getElementsByTagName("user");//array
