<?php
	//將timestamp,nonce,token按字典序排序
	$timestamp?=?$_GET['timestamp'];
	$nonce?????=?$_GET['nonce'];
	$token?????=?'weixin';
	$signature?=?$_GET['signature'];
	$array?????=?array($timestamp,$nonce,$token);
	sort(?$array?);
	//將排序后的三個參數拼接之后用shal加密
	$tmpstr?=?implode('',$array);
	$tmpstr?=?shal($tmpstr);
	//將加密后的字符串與signature進行對比，判斷該請求是否來自微信
	if($tmpstr?==?$signature){
		echo?$_GET['echostr'];
		exit;
	}