ajax使用之动态显示商品信息

来源：互联网发布：星辰0灯尤格萨隆数据编辑：程序博客网时间：2024/06/15 23:52

上一篇说到了利用ajax技术实现无刷新验证用户名，这篇将介绍无刷新获取后台商品信息并显示出来。实现的效果如下：

前台的操作逻辑和前面介绍的都差不多。都是获取XMLHttpRequest对象并进行请求监听等等。获取XMLHttpRequest对象封装在了util.js里面了。

util.js里代码如下：

/** * 得到XMLHttpRequest对象 */function getXHR(){var xmlHttp;try {xmlHttp=new XMLHttpRequest();}catch(e){try{xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");}catch(e){try{xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");}catch(e){alert("你的浏览器不支持ajax");return false;}}}return xmlHttp;}

前台页面代码如下:

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><style type="text/css">.odd{background-color:#c3f3c3;}.even{background-color:#f3c3f3;}</style><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><script type="text/javascript" src="${pageContext.request.contextPath}/util.js"></script><title>ajax用户名验证</title><script>window.onload = function() {document.getElementById("bt1").onclick = function() {//发出已补请求//1/得到xhr对象var xhr = getXHR();//2.注册状态变化监听器xhr.onreadystatechange = function() {if (xhr.readyState == 4) {if (xhr.status == 200) {document.getElementById("div1").innerHTML = xhr.responseText;}}}//3.建立与服务器的连接xhr.open("POST", "AjaxDemo2" + "?time=" + new Date().getTime());xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");//4.向服务器发出请求xhr.send();}}</script></head><body><button id="bt1">获取商品信息</button><div id="div1"></div></body></html>

后台servlet代码如下：

package com.levi.servletajax;import java.io.IOException;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.levi.domain.Product;/** * Servlet implementation class AjaxDemo2 */public class AjaxDemo2 extends HttpServlet {private static final long serialVersionUID = 1L;private List<Product>products=new ArrayList<Product>();           /**     * @see HttpServlet#HttpServlet()     */    public AjaxDemo2() {        super();        // TODO Auto-generated constructor stub    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overridepublic void init() throws ServletException{products.add(new Product(1, "篮球", 300));products.add(new Product(2, "足球", 100));products.add(new Product(3, "乒乓球",50));products.add(new Product(4, "羽毛球",100));products.add(new Product(5, "排球", 120));}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setAttribute("products", products);request.getRequestDispatcher("/listProducts.jsp").forward(request, response);}}

其中这里通过服务器转发到了listProducts.jsp这里，这里进行的是显示所有商品的代码。因为返回的是jsp文件，也就是相当于把所有的代码返回了。返回到前面前台页面的的div里面，达到了动态显示的效果。

listProducts.jsp中代码如下

<%@ 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>Insert title here</title></head><body><table border="1" width="438"><tr><th>编号</th><th>名称</th><th>单价</th></tr><c:forEach items="${products }" var="p" varStatus="vs"><tr class="${vs.index%2==0?'odd':'even'}"><th>${p.id }</th><th>${p.name }</th><th>${p.price }</th></tr></c:forEach></table></body></html>

其中这里稍微难理解的就是前台xhr.responseText获取到的文本数据其实就是那整个jsp文件。

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