PHP实现自动识别Restful API的返回内容类型

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

<?php
// 请求初始化
$url = 'https://www.jb51.net';
$ch = curl_init();
curl_setopt($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, 'content_type');

// 关闭请求资源
curl_close($ch);

// 结果自动格式输出
$autoDetectFormats = array(
 'application/xml' => 'xml',
 'text/xml'  => 'xml',
 'application/json' => 'json',
 'text/json'  => 'json',
 'text/csv'  => 'csv',
 'application/csv' => 'csv',
 'application/vnd.php.serialized' => 'serialize'
);

if (strpos($contentType, ';'))
{
 list($contentType) = explode(';', $contentType);
}

$contentType = trim($contentType);

if (array_key_exists($contentType, $autoDetectFormats))
{
 echo '_' . $autoDetectFormats[$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, 'SimpleXMLElement', LIBXML_NOCDATA) : array();
}

/**
 * 格式化csv输出
 */
function _csv($string)
{
 $data = array();

 $rows = explode("\n", trim($string));
 $headings = explode(',', array_shift($rows));
 foreach( $rows as $row )
 {
 // 利用 substr 去掉 开始 与 结尾 的 "
 $data_fields = explode('","', trim(substr($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;
}