使用该json_decode函数将JSON字符串转换为对象数组，然后遍历该数组直到找到所需的对象：

$str = '{
  "people":[
    {
      "id": "8080",
      "content": "foo"
    },
    { 
      "id": "8097",
      "content": "bar"
    }
  ]
}';

$json = json_decode($str);
foreach ($json->people as $item) {
    if ($item->id == "8097") {
        echo $item->content;
    }
}