<?php

//获得参数 signature nonce token timestamp echostr

$nonce     = $_GET['nonce'];

$token     = 'imooc';

$timestamp = $_GET['timestamp'];

$echostr   = $_GET['echostr'];

$signature = $_GET['signature'];

//形成数组，然后按字典序排序

$array = array();

$array = array($nonce, $timestamp, $token);

sort($array);

//拼接成字符串,sha1加密 ，然后与signature进行校验

$str = sha1( implode( $array ) );

if( $str  == $signature && $echostr ){

//第一次接入weixin api接口的时候

echo  $echostr;

exit;

}