PHP implements automatic identification of the return content type of Restful API

如题，PHP如何自动识别第三方Restful API的内容，自动渲染成 json、xml、html、serialize、csv、php等数据？

其实这也不难，因为Rest API也是基于http协议的，只要我们按照协议走，就能做到自动化识别 API 的内容，方法如下：

1、API服务端要返回明确的 http Content-Type头信息，如：

Content-Type: application/json; charset=utf-8
Content-Type: application/xml; charset=utf-8
Content-Type: text/html; charset=utf-8

2、PHP端（客户端）接收到上述头信息后，再酌情自动化处理，参考代码如下：

<?php
// 请求初始化
$url = &#39;http://www.php.cn&#39;;
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
 
// 返回的 http body 内容
$response = curl_exec($ch);
 
// 返回的 http header 的 Content-Type 的内容
$contentType = curl_getinfo($ch, &#39;content_type&#39;);
 
// 关闭请求资源
curl_close($ch);
 
// 结果自动格式输出
$autoDetectFormats = array(
 &#39;application/xml&#39; => &#39;xml&#39;,
 &#39;text/xml&#39;  => &#39;xml&#39;,
 &#39;application/json&#39; => &#39;json&#39;,
 &#39;text/json&#39;  => &#39;json&#39;,
 &#39;text/csv&#39;  => &#39;csv&#39;,
 &#39;application/csv&#39; => &#39;csv&#39;,
 &#39;application/vnd.php.serialized&#39; => &#39;serialize&#39;
);
 
if (strpos($contentType, &#39;;&#39;))
{
 list($contentType) = explode(&#39;;&#39;, $contentType);
}
 
$contentType = trim($contentType);
 
if (array_key_exists($contentType, $autoDetectFormats))
{
 echo &#39;_&#39; . $autoDetectFormats[$contentType]($response);
}
 
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++
// 常用 格式化 方法
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
/**
 * 格式化xml输出
 */
function _xml($string)
{
 return $string ? (array)simplexml_load_string($string, &#39;SimpleXMLElement&#39;, LIBXML_NOCDATA) : array();
}
 
/**
 * 格式化csv输出
 */
function _csv($string)
{
 $data = array();
 
 $rows = explode("\n", trim($string));
 $headings = explode(&#39;,&#39;, array_shift($rows));
 foreach( $rows as $row )
 {
 // 利用 substr 去掉 开始 与 结尾 的 "
 $data_fields = explode(&#39;","&#39;, trim(substr($row, 1, -1)));
 if (count($data_fields) === count($headings))
 {
  $data[] = array_combine($headings, $data_fields);
 }
 }
 
 return $data;
}
 
/**
 * 格式化json输出
 */
function _json($string)
{
 return json_decode(trim($string), true);
}
 
/**
 * 反序列化输出
 */
function _serialize($string)
{
 return unserialize(trim($string));
}
 
/**
 * 执行PHP脚本输出
 */
function _php($string)
{
 $string = trim($string);
 $populated = array();
 eval("\$populated = \"$string\";");
 
 return $populated;
}

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