php输出json 对象{‘code’:200,'data':对象模式}

<?php
class Cat{
public $name;
//public function __construct() {
// $this->name = $name;
//}
public function input($cityID){
$this->name = $cityID;
}
}

class Data{
public $code;
public $data;
public function input($de,$da){
$this->code = $de;
$this->data = $da;
}

}
$arrays=array();
$cat1=new Cat();
$cat1->input("Tom1") ;
array_push($arrays,$cat1);
$cat2=new Cat();
$cat2->input("Tom2") ;
array_push($arrays,$cat2);
$cat3=new Cat();
$cat3->input("Tom3");
array_push($arrays,$cat3);
$data=new Data();
$data->input("200",$arrays);
//$ary=array($cat1,$cat2,$cat3);
echo "<br/>";
//echo implode(",",$ary);
//echo json_encode($arrays);
echo json_encode($data);

?>