Example 1: An example of using Ajax to dynamically obtain time.
HTML code:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> <script type="text/javascript" src="Scripts/jquery-1.7.1.js"></script> <script type="text/javascript" src="Scripts/jwy.js"></script> </head> <body> <form id="form1" runat="server"> <div> <input type="text" name="textbox" id="text1" /> <input type="button" name="button" id="Button1" value="显示时间" onclick="btnclick()" /> </div> </form> </body> </html>
Create a "general handler" to handle foreground requests and return the current system time:
Handler.ashx
<%@ WebHandler Language="C#" Class="Handler" %> using System; using System.Web; using System.Linq; using System.Collections.Generic; using System.Text; public class Handler : IHttpHandler { public void ProcessRequest (HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write(ShowTime()); } public bool IsReusable { get { return false; } } public static string ShowTime() { return DateTime.Now.ToString(); } }
js code:
function btnclick() { var httprequest = null; // 初始化XMLHttpRequest对象 if (window.XMLHttpRequest) { // Firefox等现代浏览器中的XMLHttpRequest对象创建 httprequest = new XMLHttpRequest(); } else if (window.ActiveXObject) { // IE中的XMLHttpRequest对象创建 httprequest = new ActiveXObject("Microsoft.XMLHTTP"); } if (!httprequest) { alert("创建httprequest对象出现异常!"); } httprequest.open("POST", "Handler.ashx", true); //httprequest向handler发送post请求,最后参数是设定是否为异步请求,true为异步,false为同步 httprequest.onreadystatechange = function () { //指定onreadystatechange事件句柄对应的函数 if (httprequest.readyState == 4) { //4代表服务器返回完成 if (httprequest.status == 200) { //200代表成功了 document.getElementById("text1").value = httprequest.responseText; //responsetext表示服务器返回的文本,还有一种方式是responseXML是为了获取服务器返回的xml } else { alert("AJAX服务器返回错误!"); } } } httprequest.send(); //在这里才真正的向服务器端发送请求 }
We use jquery to make the front-end js code very simple:
JS code based on jquery:
Note: The HTML code needs to remove the onclick event of the button, because we use event binding directly in js.
$(document).ready(function () { //button1绑定事件 $("#Button1").bind("click", function () { $.ajax({ url: "Handler.ashx", type: "POST", success: function (data) { //$("#text1").val(data); document.getElementById("text1").value = data; } }); }); });
I have to say that jquery is "simple but not simple"...
$.ajax in jquery integrates get and post methods, and the default is get.
If you use POST directly, the code is simpler
$(document).ready(function () { //button1绑定事件 $("#Button1").bind("click", function () { $.post("Handler.ashx", function (data) { document.getElementById("text1").value = data; }); }); });
Example 2:
1. XMLHttpRequest implementation to obtain data
Do not use jQuery to achieve the method of obtaining content without refreshing the page. We use XMLHttpRequest native code to implement it here;
js code is as follows:
//1.获取a节点,并为其添加Oncilck响应函数 document.getElementsByTagName("a")[0].onclick = function(){ //3、创建一个XMLHttpRequest(); var request = new XMLHttpRequest(); //4、准备发送请求的数据url var url = this.href; var method = "GET"; //5、调用XMLHttpRequest对象的open方法 request.open(method,url); //6、调用XMLHttpRequest对象的send方法 request.send(null); //7、为XMLHttpRequest对象添加onreadystatechange 响应函数 request.onreadystatechange = function(){ //8、判断响应是否完成:XMLHttpRequest 对象的readystate的属性值为4的时候 if(request.readyState == 4){ //9、在判断响应是否可用:XMLHttpRequest 对象status 属性值为200 if(request.status == 200){ //10、响应结果 alert(request.responseText); } } } //2、取消a节点的额默认行为 return false; }
Insert HTML code:
<a href = "hello.txt">点击获取文本内容</a>
2. jQuery implements ajax to obtain information
This example is to dynamically obtain data from the background to change the content of the drop-down button;
js code is as follows:
function bindCarteam0(){ //通过URL请求数据 var URL = <select:link page="/xiaoshouwl.do?method=getCarteamList"/>; $.ajax({ url:URL, type:'GET', dataType: "json", success:function(html){ var str="<option value='-1'>全部</option>"; for(var i=0;i<html.length;i++){ str+="<option value='"+html[i].id+"'>"+html[i].name+"</option>"; } $("#carteam_code").empty().html(str); } }); }
HTML code is as follows:
<select:select property="carteam_code" styleId="carteam_code" style="width:150px"> <select:option value="-1">全部</select:option> </select:select>
There are two types of types: get and post;
The amount of data that post can transmit is relatively large, and get has a byte limit;

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