<?php

header('Content-type:text/html;charset=utf-8');

$s = array('message'=>'4月以降、遺体の捜索活動が続けられてきたが');

$sJSON = json_encode($s);

var_dump($sJSON); // 会转换成16进制

var_dump(json_decode($sJSON));

$sJSON = json_encode($s, defined('JSON_UNESCAPED_UNICODE') ? JSON_UNESCAPED_UNICODE : 0);

if (!defined('JSON_UNESCAPED_UNICODE') && function_exists('mb_convert_encoding')) {

  $sJSON = preg_replace_callback(

    '~\\\\u([0-9a-f]{4})~i',

    create_function('$aMatches', 'return mb_convert_encoding(pack("H*", $aMatches[1]), "UTF-8", "UTF-16");'),

    $sJSON);

}

var_dump($sJSON);

var_dump(json_decode($sJSON));