废话不多说，直接上代码

define("TOKEN",  config("wx_token"));
$wechatObj = new Wxapi();
if (isset($_GET['echostr'])) {
    $wechatObj->valid();
}else{
    $wechatObj->responseMsg();
}
class Wxapi
{
/**
 * 微信公众号验证
 */
public function valid()
{
    $echoStr = $_GET["echostr"];
    if($this->checkSignature()){
        echo $echoStr;
        exit;
    }
}

private function checkSignature()
{
    $signature = $_GET["signature"];
    $timestamp = $_GET["timestamp"];
    $nonce = $_GET["nonce"];

    $token = TOKEN;
    $tmpArr = array($token, $timestamp, $nonce);
    sort($tmpArr);
    $tmpStr = implode( $tmpArr );
    $tmpStr = sha1( $tmpStr );

    if( $tmpStr == $signature ){
        return true;
    }else{
        return false;
    }
}

public function responseMsg()
{
    //$postArr = $GLOBALS['HTTP_RAW_POST_DATA'];
    $postArr  = file_get_contents('php://input');
    //2.处理消息类型，并设置回复类型和内容
    $postObj = simplexml_load_string( $postArr );
    //判断该数据包是否是订阅的事件推送
    if(strtolower( $postObj->MsgType) == 'event'){
        //如果是关注 subscribe 事件
        // 超链接里边指定data-miniprogram-path跳转小程序某个页面
        if( strtolower($postObj->Event == 'subscribe') ) {
            Log::info("有人关注");
            Log::info("1");
            //回复用户消息(纯文本格式)
            $fromUsername = $postObj->FromUserName; //请求消息的用户
            $toUsername = $postObj->ToUserName; //"我"的公众号id
            $keyword = trim($postObj->Content); //消息内容
            $time = time(); //时间戳
            $msgtype = 'text'; //消息类型：文本
            $textTpl = "<xml>
            <ToUserName><![CDATA[%s]]></ToUserName>
            <FromUserName><![CDATA[%s]]></FromUserName>
            <CreateTime>%s</CreateTime>
            <MsgType><![CDATA[%s]]></MsgType>
            <Content><![CDATA[%s]]></Content>
            </xml>";

            if(strtolower($postObj->MsgType == 'event' )){ //如果XML信息里消息类型为event
                if($postObj->Event == 'subscribe'){ //如果是订阅事件
                    $contentStrq = $content = '欢迎关注';
                    $resultStrq = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgtype, $contentStrq);
                    echo $resultStrq;
                    exit();//一定要加！！！！不加程序运转正常就是不回复消息
                }
            }
        }
    }
}

}