这不就是个json吗？ php的系统函数 json_encode() 可以把数组转化成json

具体怎么写呢？我现在的QR.php生成的是二维码图片，代码如下：
<?php

include "phpqrcode/phpqrcode.php"; 

$url = 'http://wx.weiaitang.com/'.$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF'].'?'.$_SERVER['QUERY_STRING'];
$burl = strstr( $url,'qr.php');
$qurl = strstr( strstr( $url, '?url='), 'http');
if ($burl !== "qr.php?" and strpos($burl,'?url=http://') !== false) {
$value=$qurl;
}
else {
$value = "http://wx.weiaitang.com/";
}

$errorCorrectionLevel = "L"; 
$matrixPointSize = "8"; 
$margin="1";
QRcode::png($value, false, $errorCorrectionLevel, $matrixPointSize,$margin); 
echo $burl;
exit; 

?>