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用.net 处理xmlhttp发送异步请求_asp.net技巧

2007-08-24 分类：ASP.NET教程阅读(763) 评论(0)

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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=”http://www.knowsky.com/javascript/prototype/extras-array.js”></script>
   <script language=”javascript” src=”http://www.knowsky.com/javascript/xmlHttp.js”></script>
   <script language=”javascript” src=”http://www.knowsky.com/javascript/eventRouter.js”></script>
    <script language=”javascript” src=”http://www.knowsky.com/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
    loadTestPost();
    //绑定Get发送xmlHttp事件到btnTestGet
    loadTestGet();
};

最后是.net处理xmlHttp的代码
.net 处理xmlHttp请求
public class DefaultHandler : IHttpHandler
{
protected XmlDocument _xmlResult;

        public void ProcessRequest(HttpContext context)
        {
            if (context.Request[“T”] != null)
            {//GET xmlhttp测试
                context.Response.ContentType = “text/xml”;
                XmlDocument xmlDoc = new XmlDocument();
                xmlDoc.LoadXml(string.Format(@”<time>GET:{0}</time>”, System.DateTime.Now));
                xmlDoc.Save(context.Response.OutputStream);
                context.Response.End();
            }
            else
            {//POST xmlhttp测试
                context.Response.ContentType = “text/xml”;
                XmlDocument xmlDoc = new XmlDocument();
                xmlDoc.Load(context.Request.InputStream);
                if (xmlDoc.DocumentElement.Name == “T”)
                {
                    xmlDoc.LoadXml(string.Format(@”<time>POST:{0}</time>”, System.DateTime.Now));
                    xmlDoc.Save(context.Response.OutputStream);
                    context.Response.End();
                }
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }

http://www.cnblogs.com/Files/laiwen/XmlHttpNet.rar
http://www.cnblogs.com/laiwen/archive/2006/12/26/604050.html

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