php json_encode() does not output Chinese

php json_encode() does not output Chinese, but characters such as "u4e2du6587" appear.

Php code

<?php  
echo json_encode("中文");  
   
//"\u4e2d\u6587"  
 如何让它变成中文呢？就要使用JSON_UNESCAPED_UNICODE，让JSON不要输出Unicode编码。

Php code

<?php  
echo json_encode("中文", JSON_UNESCAPED_UNICODE);  
   
//"中文"