用.net 处理xmlHttp发送异步请求

2008-02-22 09:41:42来源：互联网阅读 ()

最近正在拜读<<Ajax in Action>>这本书，运用书中知识，结合.net，写了这篇用.net 处理xmlHttp发送异步请求的文章。

我们要达到的目的是点击按钮，获得服务器的当前时间，aspx的html如下：
Html
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="Linkedu.Web.WebWWW.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>测试</title>
<script language="javascript" src="javascript/prototype/extras-array.js"></script>
<script language="javascript" src="javascript/xmlHttp.js"></script>
<script language="javascript" src="javascript/eventRouter.js"></script>
<script language="javascript" src="Default.js"></script>
<script language="javascript">

</script>
</head>
<body>
<form id="form1" runat="server">
用Post方式获得服务器的当前时间
<input id="btnTestPost" type="button" value="Post" />
用Get方式获得服务器的当前时间
<input id="btnTestGet" type="button" value="Get" />
<div id="divResult"></div>
</form>
</body>
</html>

要用javascript 发送xmlHttp 请求必须解决的问题是跨浏览器的支持。我们把xmlHttp的发送封装在一个javascript对象中，同时在这个对象中解决了跨浏览器支持的问题。代码如下：

xmlHttp对象
/**//*
url-loading object and a request queue built on top of it
*/

/**//* namespacing object */
var net=new Object();

net.READY_STATE_UNINITIALIZED=0;
net.READY_STATE_LOADING=1;
net.READY_STATE_LOADED=2;
net.READY_STATE_INTERACTIVE=3;
net.READY_STATE_COMPLETE=4;

/**//*--- content loader object for cross-browser requests ---*/
net.xmlHttp=function(url, onload, params, method, contentType, onerror){
this.req=null;
this.onload=onload;
this.onerror=(onerror) ? onerror : this.defaultError;
if(typeof(method) == "undefined" || method == null)
{
method = "POST";
}
this.loadXMLDoc(url, params, method, contentType);
}

net.xmlHttp.prototype.loadXMLDoc=function(url, params, method, contentType){
if (!method){
method="GET";
}
if (!contentType && method=="POST"){
contentType='application/x-www-form-urlencoded';
}
if (window.XmlHttpRequest){
this.req=new XmlHttpRequest();
} else if (window.ActiveXObject){
this.req=new ActiveXObject("Microsoft.xmlHttp");
}
if (this.req){
try{
var loader=this;
this.req.onreadystatechange=function(){
net.xmlHttp.onReadyState.call(loader);
}
this.req.open(method,url,true);
if (contentType){
this.req.setRequestHeader('Content-Type', contentType);
}
this.req.send(params);
}catch (err){
this.onerror.call(this);
}
}
}

net.xmlHttp.onReadyState=function(){
var req=this.req;
var ready=req.readyState;
if (ready==net.READY_STATE_COMPLETE){
var httpStatus=req.status;
if (httpStatus==200 || httpStatus==0){
this.onload.call(this);
}else{
this.onerror.call(this);
}
}
}

net.xmlHttp.prototype.defaultError=function(){
alert("error fetching data!"
"\n\nreadyState:" this.req.readyState
"\nstatus: " this.req.status
"\nheaders: " this.req.getAllResponseHeaders());
}

下面开始写发送xmlHttp请求的代码：

default.js
//全局xmlHttp对象
var cobj;

/**//* Post begin*/
//绑定Post发送xmlHttp事件到btnTestPost
function loadTestPost()
{
var iobj = document.getElementById("btnTestPost");
//btnTestPost按钮监听的绑定
var clickRouter=new jsEvent.EventRouter(iobj,"onclick");
clickRouter.addListener(btnTestPostClick);
}
function btnTestPostClick()
{ // open参数 url, onload, params, method, contentType, onerror
cobj = new net.xmlHttp("DefaultHandler.ashx",dealResult, "<T/>", "POST");
}
/**//* Post end*/

/**//* Get begin*/
//绑定Get发送xmlHttp事件到btnTestGet
function loadTestGet()
{
var iobj = document.getElementById("btnTestGet");
//btnTestGet按钮监听的绑定
var clickRouter=new jsEvent.EventRouter(iobj,"onclick");
clickRouter.addListener(btnTestGetClick);
}
function btnTestGetClick()
{ // open参数 url, onload, params, method, contentType, onerror
cobj = new net.xmlHttp("DefaultHandler.ashx?T=1",dealResult, null, "GET");
}
/**//* Get end*/

function dealResult()
{
var dobj = document.getElementById("divResult");
dobj.innerHTML = cobj.req.responseXML.text;
}

window.onload = function()
{
//绑定Post发送xmlHttp事件到btnTestPost

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