protected function renderJSON($data=[], $msg ="ok", $code = 200)
{
    //设置格式
    header('Content-type: application/json');
    //输出json格式的内容
    print_r(json_encode([
      "code" => $code,
      "msg"  => $msg,
      "data" => $data,
      "req_id" => uniqid()
    ]));
    //结束
    return Yii::$app->end();
}
 

<?php
// 告诉浏览器以json编码
header('Content-type:text/json');
$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
// 没有设置则输出对象
var_dump(json_decode($json));
echo "<br>";
// 为true则为输出数组
var_dump(json_decode($json, true));
echo "<br>";
$array=array('a','f','q','d','a','g');
var_dump(json_encode($array,JSON_HEX_TAG));
?>
 

<?php
// 告诉浏览器以json编码
header('Content-type:text/json');
$json = '{"fruit":{{"apple":"苹果"},{"banana":"苹果"}}';
// string(49) "{"fruit":{{"apple":"苹果"},{"banana":"苹果"}}"
var_dump($json);