用Ajax发送请求，查询数据库是否有自己的数据，如果有自己的数据，就返回
前端页面
<head>
<meta charset="UTF-8">
<title>登录聊天室</title>
<?php
session_start();
$sender = $_SESSION[‘loginuser‘];
$username = $_GET[‘username‘];
?>
<meta name="name" content="content" charset="utf-8">
<script type="text/javascript">
function ismsg(){//是否有信息
var xhr=myAjax();
xhr.open(‘post‘,‘ismsg.php‘,true);
xhr.setRequestHeader(‘content-type‘,‘application/x-www-form-urlencoded‘);
xhr.onreadystatechange=function (){
if(this.readyState==4){
$(‘mymess‘).innerHTML+=this.responseText;
}
}
var name=$(‘user‘).innerHTML;
//alert(name);
xhr.send(‘username=‘+name);
}
function sendMessage(){
ismsg();
var myXmlHttpRequest = myAjax();
//alert(myXmlHttpRequest);
if(myXmlHttpRequest){
var url = "sendMessage.php";
var data = "con="+$(‘con‘).value+"&getter=<?php echo $username;?>&sender=<?php echo $sender;?>";
//alert($(‘con‘).value);
myXmlHttpRequest.open(‘post‘,url,true);
myXmlHttpRequest.onreadystatechange = function(){
if(myXmlHttpRequest.readyState == 4){
//alert(‘das‘);
//document.getElementById(‘re‘).innerHTML=myXmlHttpRequest.responseText;
if(myXmlHttpRequest.status == 200){
//alert(200);
//alert(myXmlHttpRequest.responseText);
if(myXmlHttpRequest.responseText ==1){
var con = $(‘con‘).value;
$(‘mymess‘).innerHTML += "<br/>"+"<?php echo $sender;?> "+show()+"<br/>"+con+"\n"+"<br/>";
$(‘con‘).value = ‘‘;
//ismsg();
}
}
}
}
myXmlHttpRequest.setRequestHeader(‘Content-Type‘,‘application/x-www-form-urlencoded‘);
myXmlHttpRequest.send(data);
}
}
//获取响应ID信息的公用函数
function $(id){
return document.getElementById(id);
}
//考虑浏览器兼容创造ajax对象
function myAjax(){
var myAjax = false;
if(window.XMLHttpRequest){
myAjax = new XMLHttpRequest();
}else{
myAjax = new window.Activexobject(‘Microsoft.XMLHttp‘);
}
return myAjax;
}
function show(){
var date = new Date();
var now = "";
now = date.getFullYear()+"-";
now = now + (date.getMonth()+1)+"-";
now = now + date.getDate()+" ";
now = now + date.getHours()+":";
now = now + date.getMinutes()+":";
now = now + date.getSeconds()+"";
return now;
}
</script>
</head>
<body>
<h1>聊天室(<span id=‘user‘><?php echo $sender;?></span>正在与<?php echo $username;?>)聊天</h1>
<div id="re"></div>
<div style="width:500px; height:400px; overflow:auto; border:1px solid green; background=grey;" id="mymess"></div><br />
<input type="text" id="con" style="width:375px;">
<input type="button" value="发送" onclick="sendMessage();">
<input type="button" value="看看有没有信息" onclick="ismsg();"/>
</body>
</html>
ismsg.php
<?php
header("Content-type:text/html;charset=utf-8");
//获取所有未读的信息
require(‘./mysql.php‘);
$mysql=mysql::getIns();
$sql="select * from messages where isget=0 and geter=‘".$_POST[‘username‘]."‘";
$rs=$mysql->getAll($sql);
$str=‘‘;
//echo ‘haha‘;
if($rs){
foreach($rs as $v){
echo $v[‘sender‘].‘ ‘.date(‘Y-m-d H:i:s‘).‘<br/>‘.$v[‘content‘].‘<br/>‘;
}
//echo $str;
}
$sql="update messages set isget=1 where isget=0 and geter=‘".$_POST[‘username‘]."‘";
$mysql->query($sql);
?>
sendMessage.php
<?php
header("Content-type:text/html;charset=utf-8");
$sender = $_POST[‘sender‘];
$getter = $_POST[‘getter‘];
$con = $_POST[‘con‘];
//echo $con;
//echo $sender,$getter,$con;
echo add_message($sender,$getter,$con);
//file_put_contents(‘send.txt‘,$sender."-".$getter."-".$con."\t\n",FILE_APPEND);
function sql_con(){
$link = mysql_connect(‘localhost‘,‘root‘,‘111111‘);
if(!$link){
echo "连接失败".mysql_error();die;
}
//mysql_select_db(‘chatroom‘,$link);
//mysql_query(‘set names utf8‘);
return $link;
}
function add_message($sender,$getter,$con){
$conn=sql_con();
mysql_query(‘use chatroom‘,$conn);
mysql_query(‘set names utf8‘,$conn);
$sql = "insert into messages(sender,geter,content,sendtime) values(‘$sender‘,‘$getter‘,‘$con‘,now())";
//echo $sql;
$res = mysql_query($sql,$conn);
//print_r($res);
return $res;
}
?>
原文：http://www.cnblogs.com/lzzhuany/p/4893343.html