PHPで配列をJSONに変換

$array_1 = array(); //一维数组
$array_2 = array(); //多维数组
$array_1['username']='ericwolf';
$array_1['age']=25;
$array_2['menber']['aa']['username']='ericwolf';
$array_2['menber']['aa']['age']=25;
$array_2['menber']['bb']['username']='eeee';
$array_2['menber']['bb']['age']=22;
print_r($array_2);
$jsonObj_1 = json_encode($array_1);
var_dump($jsonObj_1);
$jsonObj_1 = json_encode($array_2);
var_dump($jsonObj_1);
运行结果：
Array
(
    [menber] => Array
        (
            [aa] => Array
                (
                    [username] => ericwolf
                    [age] => 25
                )
            [bb] => Array
                (
                    [username] => eeee
                    [age] => 22
                )
        )
)
string(32) "{"username":"ericwolf","age":25}"
string(84) "{"menber":{"aa":{"username":"ericwolf","age":25},"bb":{"username":"eeee","age":22}}}"