User login page (js implements ajax request in get mode)
login.html code is as follows:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<hr size="1">
用户：<input type="text" id="username" name="username"/><br>
密码：<input type="password" id="password" name="password" /><br>
<div id="error_message" style="color: red"></div>
<input type="submit" id='login' name='login' value="登录">
<div id="success"></div>
</body>
<script type="text/javascript">
document.getElementById("login").onclick = function () {
var name = document.getElementById("username").value;
var pwd = document.getElementById("password").value;
var oError = document.getElementById("error_message");
var isNotError = true;
if(name==""){
oError.innerHTML = "警告:用户名为空 ";
isNotError = false;
return;
}else if(pwd==""){
oError.innerHTML = "警告:密码为空 ";
isNotError = false;
return;
}
//创建XHR对象
var xhr = new XMLHttpRequest();
//设置请求URL
var url = "./success.php?username=" + name+"&password="+pwd;
//设置XHR对象readyState变化时响应函数
xhr.onreadystatechange = function () {
var success = document.getElementById("success");
//readyState是请求的状态，为4表示请求结束
if (xhr.readyState == 4) {
//responseText服务器响应的内容
var data = eval(this.responseText);
for(var index in data) {
if(data[index].code==1){
alert(data[index].message);//密码错误
}else if(data[index].code==2){
alert(data[index].message);//您已经登入了
success.innerHTML = "用户名："+data[index].session+"---"+"<a href='logout.php'>注销</a>";;
}else if(data[index].code==3){
alert(data[index].message);//登录成功
success.innerHTML = "您好！"+data[index].session+",欢迎回来！<a href='logout.php'>注销</a>";
}
else if(data[index].code==4){
alert(data[index].message);//没有此用户,请重新登录
location.href='login.html';
}
}
}
};
//打开链接
xhr.open("get", url, true);
//发送请求
xhr.send();
}
</script>
</html>ajax The submitted url address is success.php. In success.php, the database is connected and the data is processed. Then it is returned to the login page in json format and displayed, and is printed and viewed through alert
success.php code is as follows:
<?php
/**
* Created by PhpStorm.
* User: Administrator
* Date: 2018/2/27 0027
* Time: 上午 10:47
*/
header('Content-type:text/html;charset=utf-8');
if ($_SERVER['REQUEST_METHOD'] == 'GET') {
$username=trim($_GET['username']);
$password=$_GET['password'];
}
$mysqli = new mysqli('localhost', 'root', 'root', 'student');
$result = $mysqli->query("SELECT password FROM user WHERE username = "."'$username'");
$rs=$result->fetch_row();
if (!empty($rs)){
if ($password != $rs[0]) {
$data = array(
array('code' => 1, 'message' => '密码错误,请重新登录'),
);
echo json_encode($data);
}else{
$expire=3600;
ini_set('session.gc_maxlifetime', $expire);//保存1小时
if (empty($_COOKIE['PHPSESSID'])) {
session_set_cookie_params($expire);
session_start();
}else{
session_start();
setcookie('PHPSESSID', session_id(), time() + $expire);
}
if(isset($_SESSION['username'])){
$data = array(
array('code' => 2, 'message' => '您已经登入了，请不要重新登入','session'=>$_SESSION['username']),
);
echo json_encode($data);
}else{
$_SESSION['username']=$_GET['username'];
$data = array(
array('code' => 3, 'message' => '登录成功','session'=>$_SESSION['username']),
);
echo json_encode($data);
}
}
}else{
$data = array(
array('code' => 4, 'message' => '没有此用户,请重新登录'),
);
echo json_encode($data);
}
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