PHP handles ajax requests and ajax cross-domain
When sending an ajax request, you can create custom header information through the xmlHttpRequest object. In the jquery framework, when requesting web content through its $.ajax, $.get, or $.post method , it will pass an HTTP_X_REQUESTED_WITH parameter to the server. In PHP, it is judged at the header level whether it is an ajax request, and the corresponding judgment is based on $_SERVER['HTTP_X_REQUESTED_WITH']. Generally, $_SERVER['HTTP_X_REQUESTED_WITH'] defaults to XMLHttpRequest. $_SERVER['HTTP_X_REQUESTED_WITH'] can also be customized and created using XMLHttpRequest.setRequestHeader(name,value). Example: The front-end page sends a normal ajax request to the back-end test.php.
$.ajax({
type: "GET",
url: 'test.php',
success: function(data) {
console.log(data);
}
});
服务端test.php可以判断该请求是不是Ajax异步请求，然后根据业务需求做出响应的回应。 以下是服务端test.php的简单验证是否为ajax请求的代码：
function isAjax() {
return @$_SERVER['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest' ? true : false;
}
if (isAjax()) {
echo 'Ajax Request Success.';
} else {
echo 'No.';
}
Ajax发起JSONP跨域请求 我们通过jQuery的JSONP方式可以实现跨域ajax请求，服务端php也需要做出相应的处理，也就是说php这边必须和前端页面按照一定的格式请求和返回数据。 示例：前端页面发起JSONP请求：
$.ajax({
type: "get",
data: "random="+Math.random(),
url: "http://demo.thinkphp.net/phpajax/jsonp.php",
dataType: "jsonp",
jsonp: "callback",
success: function(data) {
console.log(data);
},
error: function() {
console.log('Request Error.');
}
});
我们会发现，ajax请求参数中有dataType: "jsonp"和jsonp: "callback"，这个就表明了我要请求的是jsonp，并且会有回调callback返回。当然，我们也可以自定义回调函数，如jsonpCallback:"success_jsonpCallback" 还可以简单的写成：
jQuery.getJSON('http://demo.thinkphp.net/phpajax/jsonp.php?callback=?",{
random: Math.random()
}, function(data){
console.log(data);
});
php后端服务代码可以这样写（注意输出返回的格式）：
$data = array(
'rand' => $_GET['random'],
'msg' => 'Success'
);
echo $_GET['callback'].'('.json_encode($data).')';
Ajax跨域请求：CORS CORS，又称跨域资源共享，英文全称Cross-Origin Resource Sharing。假设我们想使用Ajax从a.com的页面上向b.com的页面上要点数据，通常情况由于同源策略，这种请求是不允许的，浏览器也会返回“源不匹配”的错误，所以就有了“跨域”这个说法。但是我们也有解决办法，我们可以再b.com的页面header信息中增加一行代码：
header("Access-Control-Allow-Origin: *");
当我们设置的header为以上信息时，任意一个请求过来之后服务端我们都可以进行处理和响应，那么在调试工具中可以看到其头信息设置，其中见红框中有一项信息是“*Access-Control-Allow-Origin：* ”，表示我们已经启用CORS，如果要限制只允许某个域名的请求，可以这样：
header("Access-Control-Allow-Origin: http://www.thinkphp.com");
示例：通过CORS跨域请求数据
$.ajax({
type: "get",
data: "random="+Math.random(),
url: "http://demo.thinkphp.net/phpajax/ajax.php",
dataType: "json",
success: function(data) {
console.log(data);
$("#result_3").html(data.msg+':'+data.rand);
},
error: function() {
$("#result_3").html('Request Error.');
}
});
我们在另一个网站域名下的ajax.php加上这样的代码：
header("Access-Control-Allow-Origin: http://www.thinkphp.com");
$data = array(
'rand' => $_GET['random'],
'msg' => 'Success'
);
echo json_encode($data);The above is the detailed content of PHP handles ajax requests and ajax cross-domain. For more information, please follow other related articles on the PHP Chinese website!
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