新闻阅读器，responseXML替空

2012-10-18

新闻阅读器，responseXML为空照着书上打得，老是出错，http.responseXML is null,请各路英雄帮忙看看问题出哪

新闻阅读器，responseXML为空
照着书上打得，老是出错，http.responseXML is null,请各路英雄帮忙看看问题出哪

HTML code

<html><head><script language="javascript" src="rssd.js"></script></head><style type="text/css">.title{    font:16px bold helvetica,arial,sans-serif;    padding:0px 30px 0px 30px;    text-decoration:underline;}</style><body><h3>An Ajax RSS Reader</h3><form name="form1">URL of Rss feed:<input type="text" name="feed" size="50" value="http://"><input type="button" value="Get Feed" onclick="getRSS()"><br><div id="news"><h4>Feed Titles</h4></div></form></body></html>

JScript code

function getXMLHTTPRequest(){    var request=false;    try{        request=new XMLHttpRequest();       }     catch(err1)    {    try{        request=new ActiveXObject("Msxml2.XMLHTTP");       }    catch(err2)    {    try{        request=new ActiveXObject("Microsoft.XMLHTTP");       }    catch(err3)       {        request=false;       }    }    }    return request;}var http=getXMLHTTPRequest();function getRSS(){    var myurl='rssproxy.php?feed=';    var myfeed=document.form1.feed.value;    myRand=parseInt(Math.random()*999999999);    var modurl=myurl+escape(myfeed)+"&rand="+myRand;    http.open("GET",modurl,true);    http.onreadystatechange=useHttpResponse;    http.send(null);}function useHttpResponse(){    if(http.readyState==4){        if(http.status==200){/*       alert("The server said:"+http.responseText);}else{       alert("An error has occurred:"+http.statusText);}}}*/        while(document.getElementById('news').hasChildNodes())        {            document.getElementById('news').removeChild(document.getElementById('news').firstChild);        }        var titleNodes=http.responseXML.getElementsByTagName("title");    var descriptionNodes=http.responseXML.getElementsByTagName("description");    var linkNodes=http.responseXML.getElementsByTagName("link");    for(var i=1;i<titleNodes.length;i++)        {            var newtext=document.createTextNode(titleNodes[i].childNodes[0].nodeValue);            var newpara=document.createElement('p');            var para=document.getElementById('news').appendChild(newpara);            newpara.appendChild(newtext);            newpara.className="title";            var newtext2=document.createTextNode(descriptionNodes[i].childNodes[0].nodeValue);            var newpara2=document.createElement('p');            var para2=document.getElementById('news').appendChild(newpara2);            newpara2.appendChild(newtext2);            newpara2.className="descrip";            var newtext3=document.createTextNode(linkNodes[i].childNodes[0].nodeValue);            var newpara3=document.createElement('p');            var para3=docuement.getElementById('news').appendChild(newpara3);            newpara3.appendChild(newtext3);            newpara3.className="link";        }    } }}

PHP code

<?php$mysession=curl_init($_GET['feed']);curl_setopt($mysession,CURLOPT_HEADER,false);curl_setopt($mysession,CURLOPT_RETURNTRANSFER,true);$out=curl_exec($mysession);header('Content-Type:text/xml');echo $out;curl_close($mysession);?>

[解决办法]
js不能跨域

如果代码没有跨域，则返回的是正确的xml的格式吗
[解决办法]
如果跨域了的话，还是让服务器代理一下任务、在SERVER端获取远程数据吧。当然，这需要服务器的支持，可以在PHP.INI里设置一下。

PHP code

<?php   $url='http://www.baidu.com/';  $html=file_get_contents($url);  //print_r($http_response_header);  //.........?>
[解决办法]
探讨

还有为什么http.onreadystatechange=useHttpResponse;
调用useHttpResponse函数的时候不用括号呢？

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