May 08, 2021 JSON
In this section we will introduce you to JSONP.
JSON with Padding is a "usage mode" for json that allows web pages to get information from other domain names (websites), which read data across domains.
Why do we need a special technology (JSONP) to access data from different domains (websites)? This is because of the same source policy.
What is a esotho-policy? It is a well-known security policy proposed by Netscape, which is now used by all JavaScript-enabled browsers.
Jsonp is implemented by using the hashtag to obtain the characteristics of different source resources for cross-domain access to a resource.
If the customer wants to visit : /try/ajax/jsonp.php?jsonp?callbackFunction.
Suppose the customer expects to return JSON data: "customername1", "customername2".
The data that actually returns to the client is: callbackFunction ("customername1", "customername2").
The service-side file jsonp .php code is:
<?php header('Content-type: application/json');
//获取回调函数名
$jsoncallback = htmlspecialchars($_REQUEST ['jsoncallback']);
//json数据
$json_data = '["customername1","customername2"]';
//输出jsonp格式的数据
echo $jsoncallback . "(" . $json_data . ")"; ?>
<script type="text/javascript">
function onCustomerLoaded(result, methodName)
{
var html = '<ul>';
for(var i = 0; i < result.length; i++) { html += '<li>' + result[i] + '</li>';
}
html += '</ul>';
document.getElementById('divCustomers').innerHTML = html;
}
</script>
<div id="divCustomers"></div>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>JSONP 实例</title>
</head>
<body>
<div id="divCustomers"></div>
<script type="text/javascript">
function callbackFunction(result, methodName)
{
var html = '<ul>';
for(var i = 0; i < result.length; i++) { html += '<li>' + result[i] + '</li>';
}
html += '</ul>';
document.getElementById('divCustomers').innerHTML = html;
}
</script>
<script type="text/javascript" src="/try/ajax/jsonp.php?jsoncallback=callbackFunction"></script>
</body>
</html>
The above code can use examples of jQuery code:
<!DOCTYPE html>
<html>
<head>
<title>JSONP 实例</title>
<script src="http://apps.bdimg.com/libs/jquery/1.8.3/jquery.js" rel="external nofollow" ></script>
</head>
<body>
<div id="divCustomers"></div>
<script>
$.getJSON("/try/ajax/jsonp.php?jsoncallback=?", function(data) {
var html = '<ul>';
for(var i = 0; i < data.length; i++) { html += '<li>' + data[i] + '</li>';
}
html += '</ul>';
$('#divCustomers').html(html);
});
</script>
</body>
</html>