SimpleXMLElement处理CData内容为字符串
$content = simplexml_load_string(
'<content><![CDATA[Hello, world!]]></content>'
, null
, LIBXML_NOCDATA
);
$content = simplexml_load_string(
'<content><![CDATA[Hello, world!]]></content>'
, null
, LIBXML_NOCDATA
);