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Several ways to implement ajax through XMLHttpRequest and jQuery_jquery
Several ways to implement ajax through XMLHttpRequest and jQuery_jquery
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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