模仿韩顺平老师做的web聊天系统，大神帮忙看下出了啥问题
*******chatRoom.php******<html><head><?php//接受open传递的用户名 $username=$_GET['username']; $username=trim($username); session_start(); $loginuser=$_SESSION['loginuser'];?><meta http-equiv="content-type" content="text/html;charset=utf-8"/><script type="text/javascript" src="my.js"></script><script type="text/javascript"> window.resizeTo(800,700); window.setInterval("getMessage()",3000); function getMessage(){ //创建一个xmlHttpRequest对象 var myXmlHttpRequest=getXmlHttpObject(); if(myXmlHttpRequest){ var url="getMessageController.php"; var data="getter=<?php echo $loginuser; ?>&sender=<?php echo $username; ?>"; myXmlHttpRequest.open("post",url,true); myXmlHttpRequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); myXmlHttpRequest.onreadystatechange=function(){ if(myXmlHttpRequest.readyState==4){ if(myXmlHttpRequest.status==200){ var mesRes=myXmlHttpRequest.responseXML; var cons=mesRes.getElementsByTagName("con"); var sendtimes=mesRes.getElementsByTagName("sendtime"); if(cons.length!=0){ for(var i=0;i<cons.length;i++){ $("mycons").value+="<?php echo $username;?>说:"+cons[i].childNodes[0].nodeValue+"___"+sendtimes[i].childNodes[0].nodeValue; } } } } } myXmlHttpRequest.send(data); } } function sendMessage(){ //创建一个xmlHttpRequest对象 var myXmlHttpRequest=getXmlHttpObject(); if(myXmlHttpRequest){ var url="sendMessageController.php"; var data="con="+$('con').value+"&getter=<?php echo $username; ?>&sender=<?php echo $loginuser; ?>"; myXmlHttpRequest.open("post",url,true); myXmlHttpRequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); myXmlHttpRequest.onreadystatechange=function(){ if(myXmlHttpRequest.readyState==4){ if(myXmlHttpRequest.status==200){ //这里是返回信息，暂不需要 } } } myXmlHttpRequest.send(data); } }</script></head><body><center><h1 id="网页聊天室-font-nbsp-color-blue-php-nbsp-echo-nbsp-loginuser-nbsp-font-正在和-font-nbsp-color-red-php-nbsp-echo-nbsp-username-nbsp-font-聊天">网页聊天室(<font color="blue"><?php echo $loginuser; ?></font>正在和<font color="red"><?php echo $username; ?></font>聊天)</h1><textarea cols="60" rows="20" id="mycons"></textarea><br/><input type="text" style="width:300px" id="con"/><input type="button" value="发送" onclick="sendMessage()"/></center></body></html>*********getMessageController.php********<?phprequire_once 'MessageService.class.php';header("content-type:text/xml;charset=utf-8");header("Cache-Control:no-cache"): $getter=$_POST['getter']; $sender=$_POST['sender']; $messageService=new MessageService(); $messageList=$messageService->getMessage($getter,$sender); echo $messageList; ?>*********MessageService.class.php********<?phprequire_once 'SqlHelper.class.php';class MessageService{ function addMessage($sender,$getter,$con){$sql="insert into messages (sender,getter,content,sendtime) values ('$sender','$getter','$con',now())";$sqlHelper=new SqlHelper();return $sqlHelper->execute_dml($sql);} function getMessage($getter,$sender){ $sql="select * from messages where getter='$getter' and sender='$sender' and isGet=0"; $sqlHelper=new SqlHelper(); $array=$sqlHelper->execute_dql2($sql); $messageInfo="<meses>"; for($i=0;$i<count($array);$i++){ $row=$array[$i]; $messageInfo.="<mesid>{$row['id']}</mesid><sender>{$row['sender']}</sender><getter>{$row['getter']}</getter><con>{$row['content']}</con><sendtime>{$row['sendtime']}</sendtime>"; } $messageInfo.="</meses>"; $sqlHelper->close_connect(); return $messageInfo; }}?>大神帮忙看下问题出在哪了？
回复讨论(解决方案)
没仔细看。单这一句： session_start();
因其前面有html标签的输出，肯定会有“headers already sent”的错误提示的吧？
你都没说你出什么问题了，让大家如何下手
没仔细看。单这一句： session_start();
因其前面有html标签的输出，肯定会有“headers already sent”的错误提示的吧？
你都没说你出什么问题了，让大家如何下手
function getMessage(){ //创建一个xmlHttpRequest对象 var myXmlHttpRequest=getXmlHttpObject(); if(myXmlHttpRequest){ var url="getMessageController.php"; var data="getter=<?php echo $loginuser; ?>&sender=<?php echo $username; ?>"; myXmlHttpRequest.open("post",url,true); myXmlHttpRequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); myXmlHttpRequest.onreadystatechange=function(){ if(myXmlHttpRequest.readyState==4){ if(myXmlHttpRequest.status==200){ //注释1 window.alert("aaa"); var mesRes=myXmlHttpRequest.responseXML; var cons=mesRes.getElementsByTagName("con"); var sendtimes=mesRes.getElementsByTagName("sendtime"); //注释2 window.alert("bbb"); if(cons.length!=0){ for(var i=0;i<cons.length;i++){ $("mycons").value+="<?php echo $username;?>说:"+cons[i].childNodes[0].nodeValue+"___"+sendtimes[i].childNodes[0].nodeValue; } } } } } myXmlHttpRequest.send(data); } }主要就是回调函数出问题， 注释1处的能响应，但是注释2处的window.alert就无法响应。大神帮忙看下。
书写健壮的代码是很重要的
....if(myXmlHttpRequest.status==200){ var mesRes=myXmlHttpRequest.responseXML; if(mesRes.xml == '') { //如果不是 xml 对象 alert(myXmlHttpRequest.responseText);//看一下究竟返回了什么 return; }.... 这个估计也就是个外表吧，性能比较差。
聊天室，采用websockeet或comet，
其次也不必用数据库，redis或文件存储即可
书写健壮的代码是很重要的
....if(myXmlHttpRequest.status==200){ var mesRes=myXmlHttpRequest.responseXML; if(mesRes.xml == '') { //如果不是 xml 对象 alert(myXmlHttpRequest.responseText);//看一下究竟返回了什么 return; }....
这个估计也就是个外表吧，性能比较差。
聊天室，采用websockeet或comet，
其次也不必用数据库，redis或文件存储即可
header("Cache-Control:no-cache"):
这种错误，提示应该很明显吧
谢谢，已经解决了，怪我粗心了，原来是MessageService.class.php中，第二个header（）的分号写成了冒号，晕死啊！
我的错误跟你的一样，但是MessageService.class.php并没有使用header（）呀？？
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