• accp8.0转换教材第10章Ajax和jQuery理解与练习


    C/S (Client/Server)结构,即大家熟知的客户机和服务器结构。
    B/S(Browser/Server)结构即浏览器和服务器结构。

    认识ajax 、XMLHttpRequest、使用jquery实现ajax、处理json格式的响应数据、使用原生态JavaScript实现ajax

    一.杂记

    1.传统web技术和ajax的请求方式不同 ajax是只获得需要的元素  传统刷新全部

    2.ajax的全称是“Asynchronous Javascript And XML”(异步JavaScript和XML)

    3.ajax的工作流程 用户界面通过JavaScript到ajax发送http请求---服务器(处理请求)

    再返回xml/json/html数据到ajax引擎再由dom+css返回到用户界面

    4.XMLHttpRequest提供异步发送请求能力

    常用方法

    open(String method,String url,boolean async)创建一个新的HTTP请求、

    send(String data) 发送请求到服务器端、

    setRequestHeader(String header,String value)设置请求的某个HTTP头信息、

    5.老版本的IE浏览器和新版的即大部分浏览器的创建XMLHttpRequest不一样

    6.事件onreadystatechange:回调函数

    二.上机部分

    1.实现检查注册用户的邮箱是否存在(使用原生态JavaScript实现ajax)

    <div style="left: 2200px;">
    <form action="" method="get">
    注册邮箱:<input type="text" id="email" onblur="checkemail()" ><label id="samp">*</label><br/><br/>
    &nbsp;用户名:<input type="text">*<br/><br/>
    &nbsp;&nbsp;密码:<input type="password">*<br/><br/>
    确认密码:<input type="password">*<br/><br/>
    <div style="margin-left: 100px;"><input type="submit" value="注册"></div>

    </form>
    <script type="text/javascript" language="JavaScript">
    function checkemail() {
    //alert("hnjkl");
    //创建XMLHttpRequest对象
    if(window.XMLHttpRequest){//返回true时说明是新版本IE浏览器或其他浏览器
    xmlHttpRequest=new XMLHttpRequest();
    }else{//返回false时说明是老版本IE浏览器
    xmlHttpRequest=new XMLHttpRequest("Microsoft.XMLHTTP");
    }
    //设置回调函数
    xmlHttpRequest.onreadystatechange=callBack;
    //获取用户名文本框的值
    var email=$("#email").val();
    //初始化XMLHttpRequest组件
    var url="userServlet?email="+email;//服务器端URL地址,name为用户名文本框的值
    xmlHttpRequest.open("GET",url,true);
    //发送请求
    xmlHttpRequest.send(null);
    //回调函数callBack()中处理服务器响应的关键代码
    function callBack(){
    if(xmlHttpRequest.readyState==4&&xmlHttpRequest.status==200){
    var date=xmlHttpRequest.responseText;
    if(date=="true"){
    $("#samp").html("邮箱已被占用");//samp为显示消息的samp的id
    }else{
    $("#samp").html("邮箱可注册");
    }
    }
    }
    }

    </script>
    </div>

    在servlet中代码如下

    package web;

    import java.io.IOException;
    import java.io.PrintWriter;

    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;

    public class userServlet extends HttpServlet{

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    // TODO Auto-generated method stub

    request.setCharacterEncoding("UTF-8");
    boolean emailCheck=false;
    String email=request.getParameter("email");
    if("22@qq.com".equals(email)){
    emailCheck=true;

    }
    else {
    emailCheck=false;
    }
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out=response.getWriter();
    out.print(emailCheck);
    out.flush();
    out.close();

    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    // TODO Auto-generated method stub
    request.setCharacterEncoding("UTF-8");
    this.doGet(request, response);
    }
    }

    2.使用$.ajax()方法实现异步检查注册邮箱是否已存在

    <div style="left: 2200px;">
    <form action="" method="get">
    注册邮箱:<input type="text" id="email" onblur="checkemail()" ><label id="samp">*</label><br/><br/>
    &nbsp;用户名:<input type="text">*<br/><br/>
    &nbsp;&nbsp;密码:<input type="password">*<br/><br/>
    确认密码:<input type="password">*<br/><br/>
    <div style="margin-left: 100px;"><input type="submit" value="注册"></div>

    </form>
    <script type="text/javascript" language="JavaScript">
    function checkemail(){
    var email=$("#email").val();
    $.ajax({
    "url" :"userServlet",
    "type" :"get",
    "data" :"email="+email,
    "dataType" :"text",
    "success" :callBack,
    "error" :function () {
    alert("出现错误");
    }
    });
    function callBack(data) {
    if(data=="true"){
    $("#samp").html("邮箱已被占用");//samp为显示消息的samp的id
    }else{
    $("#samp").html("邮箱可注册");
    }
    }

    }
    </script>
    </div>

    3.以常见页面元素展示JSON数据

    <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
    <%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
    %>

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
    <head>
    <base href="<%=basePath%>">

    <title>My JSP 'workthree.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 rel="stylesheet" type="text/css" href="styles.css">
    -->
    <script type="text/javascript" src="js/jquery-1.8.3.js"></script>
    <script type="text/javascript">
    $(document).ready(function(){
    var personary=["大东-河南省周口13838381438市-","小顺-广东省xx市"];
    var person=[{"id":"1001","name":"大东","address":"河南省周口市","phone":"13838381438"},
    {"id":"1002","name":"小圳","address":"湖南省xx市","phone":"13838381438"},
    {"id":"1003","name":"小顺","address":"广东省xx市","phone":"13838381438"},
    {"id":"1004","name":"小莫","address":"河北省xx市","phone":"13838381438"}];
    var $divv=$("#con");
    var $table=$(" <table border='1' ></table>").append("<tr><td>ID</td><td>姓名</td><td>住址</td><td>手机</td></tr>");
    $divv.append($table);
    $(person).each(function(){
    $table.append("<tr><td>"+this.id+"</td><td>"
    +this.name+"</td><td>"
    +this.address+"</td><td>"
    +this.phone+"</td></tr>");
    });


    //2.下拉框
    var $ary=$(personary);
    //var $ul=$("#arul");
    var $sel=$("#arse");
    $ary.each(function(i) {
    $sel.append("<option value='"+(i+1)+"'>"+this+"</option>");
    });
    });
    </script>

    </head>

    <body>

    <div id="con">

    </div>
    <div id="conn">
    <select id="arse"></select>
    </div>
    </body>
    </html>

    4.在ajax中使用JSON生成管理员新闻管理页面

    //在这里页面就不上传了如有需要完整项目代码在csdn能找到 搜狗搜索 (accp8.0转换教材第X章)就能下载

    //最主要的是js

    /**
    * Created by Administrator on 2017/7/4.
    */
    $(function(){
    $.ajax({
    "url":"userServlet2",
    "type":"POST",
    "data":"por=user",
    "dataType":"json",
    "success":callBack
    });
    $("#news").click(function(){
    initnews();
    });
    $("#topics").click(function(){
    inittopics();
    });
    });

    function callBack(data){
    var $data=$(data);
    var $userul=$("#userul");
    $data.each(function(){
    $userul.append("<li>"+this.naem+"&nbsp;&nbsp;"+this.pwd+"&nbsp;&nbsp;<a href=''>修改</a>&nbsp;&nbsp;<a href=''>删除</a></li>");
    });
    }
    function initnews(){
    $.ajax({
    "url":"userServlet2",
    "type":"POST",
    "data":"por=news",
    "dataType":"json",
    "success":callNews
    });

    function callNews(news){
    //alert("ddd");
    var $userul=$("#userul").empty();
    for(var i=0;i<news.length;){
    $userul.append(
    "<li>"+news[i].title+"&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;"+news[i].author+"&nbsp;&nbsp;<a href=''>修改</a>&nbsp;&nbsp;<a href=''>删除</a></li>"
    );
    i++;
    if(i==news.length){

    break;
    }
    }

    }
    }
    function inittopics(){
    $.ajax({
    "url":"userServlet2",
    "type":"POST",
    "data":"por=top",
    "dataType":"json",
    "success":callTopics
    });

    function callTopics(top){

    var $userul=$("#userul").empty();
    for(var i=0;i<top.length;){
    //alert("ddd");
    $userul.append(
    "<li>"+top[i].topics+"&nbsp;&nbsp;<a href=''>修改</a>&nbsp;&nbsp;<a href=''>删除</a></li>"
    );
    i++;
    if(i==top.length){

    break;
    }
    }
    }
    }

    //servlet代码

    package web;

    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.List;

    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;


    import dao.newlist;
    import dao.topdao;
    import daoImpl.newlistimpl;
    import daoImpl.topimpl;
    import entity.news;
    import entity.top;


    public class userServlet2 extends HttpServlet{

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    // TODO Auto-generated method stub

    //doPost(request, response);

    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    // TODO Auto-generated method stub


    request.setCharacterEncoding("UTF-8");
    String por=request.getParameter("por");
    if(por.equals("news")){
    newlist nd=new newlistimpl();
    List<news> listnews=nd.allnewslist();
    StringBuffer newssub=new StringBuffer("[");
    for(int i=0;;){
    news n=listnews.get(i);
    newssub.append("{"title":""+n.getNtitle()+"","author":""+n.getAuthour()+""}");
    i++;
    if(i==listnews.size()){
    break;
    }else{
    newssub.append(",");
    }
    }
    newssub.append("]");
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out=response.getWriter();
    out.print(newssub);
    out.flush();
    out.close();

    }
    else if(por.equals("top")){
    topdao nd=new topimpl();
    List<top> listtop=nd.alltop();
    StringBuffer topsub=new StringBuffer("[");
    for(int i=0;;){
    top top=listtop.get(i);
    topsub.append("{"topics":""+top.getTcontent()+""}");
    i++;
    if(i==listtop.size()){
    break;
    }else{
    topsub.append(",");
    }
    }
    topsub.append("]");
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out=response.getWriter();
    out.print(topsub);
    out.flush();
    out.close();
    }
    }
    }

     5.在ajax中使用JSON生成主题管理页面

    //在上机四中

    五.总结部分

    1.传统的web开发技术通过浏览器发送请求 而ajax通过JavaScript的xmlhttprequest对象发送

    传统的响应的是一个完整页面  而JavaScript返回需要的数据

    2.Ajax 的关键元素

     →JavaScript语言:Ajax技术的主要开发语言

    →XML/JSON/HTML:用来封装数据

    →DOM(文档对象模型):修改页面元素

    →CSS:改变样式

    →Ajax引擎:即XMLHttpRequest对象

    3.创建XMLHttpRequest对象的方式(两种新的和旧的)

    欢迎提问,欢迎指错,欢迎讨论学习信息 有需要的私聊 发布评论即可 都能回复的

      原文在博客园http://www.cnblogs.com/a782126844/有需要可以联系扣扣:2265682997

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  • 原文地址:https://www.cnblogs.com/a782126844/p/7102370.html
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