<?php
$json='{"id":"0100","regionList":[{}],"pinyin":"beijing"}';
print_r(json_decode($json,true));

------解决方案--------------------
正则法：
PHP code
$s='{"id":"0100","regionList":[{JSON数据}],"pinyin":"beijing"}';
preg_match('/id":"(.*?)".+?pinyin":"(.*?)"/',$s,$m);
echo $m[1];
echo $m[2];

------解决方案--------------------
$json='{"id":"0100","regionList":[{}],"pinyin":"beijing"}';
$myArray = json_decode($json,true);
echo $myArray['id'];//输出的就是0100
echo $myArray['pinyin'];//输出的就是beijing