回答

两种方式：

第一种类似于公众号的消息接受与发送，适合小程序

首先登陆小程序后台

在开发设置中，开启消息推送服务，填写你的服务器url地址，token，选择json数据格式

php的微信小程序客服接受消息和推送消息代码

<?php
    define("TOKEN", "213123123123!1232");  //填写自己的token,跟小程序后台填的一样即可

    if (isset($_GET['echostr'])) {          //校验服务器地址URL
        valid();
    }else{
        responseMsg();
    }
     function valid()
    {
        $echoStr = $_GET["echostr"];
        if(checkSignature()){
            header('content-type:text');
            echo $echoStr;
            exit;
        }else{
            echo $echoStr.'+++'.TOKEN;
            exit;
        }
    }
     function checkSignature()
    {
        $signature = $_GET["signature"];
        $timestamp = $_GET["timestamp"];
        $nonce = $_GET["nonce"];
    
        $token = TOKEN;
        $tmpArr = array($token, $timestamp, $nonce);
        sort($tmpArr, SORT_STRING);
        $tmpStr = implode( $tmpArr );
        $tmpStr = sha1( $tmpStr );
    
        if( $tmpStr == $signature ){
            return true;
        }else{
            return false;
        }
    }
     function responseMsg()
    {
        $postStr = file_get_contents('php://input');   //此处推荐使用file_get_contents('php://input')获取后台post过来的数据

        if (!empty($postStr) && is_string($postStr)){
        $postArr = json_decode($postStr,true);
            if(!empty($postArr['MsgType']) && $postArr['Content'] == "1"){          //用户发送1,回复公众号二维码
                $fromUsername = $postArr['FromUserName'];                           //发送者openid
                //$imgurl = "/300-300.png";                                           //公众号二维码,相对路径,修改为自己的
              //  $media_id = getMediaId($imgurl);                                    //获取图片消息的media_id
                // $data=array(
                //     "touser"=>$fromUsername,
                //     "msgtype"=>"image",
                //     "image"=>array("media_id"=>$media_id)
                // );
                 $content = '你好,回复1关注公众号，回复2获取官网链接';                
                 $data=array(
                    "touser"=>$fromUsername,
                    "msgtype"=>"text",
                    "text"=>array("content"=>$content)
                );
                $json = json_encode($data,JSON_UNESCAPED_UNICODE);  //php5.4+
                requestAPI($json);
            }
            
            elseif(!empty($postArr['MsgType']) && $postArr['Content'] == "2"){      //用户发送2,回复图文链接
                $fromUsername = $postArr['FromUserName'];                           //发送者openid
                $data=array(
                            "touser"=>$fromUsername,
                            "msgtype"=>"link",
                            "link"=>array(                                          //修改下面几项为自己的
                                    "title"=>'bfw爱编程',    
                                    "description"=>'bfw爱编程，专业的技术社区',
                                    "url"=>'https://www.bfw.wiki/',
                                    "thumb_url"=>'https://repo.bfw.wiki/bfwrepo/icon/60ecf359eb0c5.png',
                                    )
                           );
                $json = json_encode($data,JSON_UNESCAPED_UNICODE);  //php5.4+
                requestAPI($json);
            }
            

            elseif(!empty($postArr['MsgType']) && $postArr['Content'] == "3"){      //用户发送3,回复文字
                $fromUsername = $postArr['FromUserName'];                           //发送者openid
                $content = '你好,回复1关注公众号，回复2获取官网链接';                 //修改为自己需要的文字
                $data=array(
                    "touser"=>$fromUsername,
                    "msgtype"=>"text",
                    "text"=>array("content"=>$content)
                );
                $json = json_encode($data,JSON_UNESCAPED_UNICODE);  //php5.4+
                requestAPI($json);
            }
                        
            
            elseif(!empty($postArr['MsgType']) && $postArr['MsgType'] == 'image'){  //用户发送图片,这里示例为回复他公众号二维码
                $fromUsername = $postArr['FromUserName'];                           //发送者openid
                $imgurl = "/300-300.png";                                           //公众号二维码,相对路径,修改为自己的
                $media_id = getMediaId($imgurl);                                    //获取图片消息的media_id
                $data=array(
                    "touser"=>$fromUsername,
                    "msgtype"=>"image",
                    "image"=>array("media_id"=>$media_id)
                );
                $json = json_encode($data,JSON_UNESCAPED_UNICODE);  //php5.4以上版本才可使用
                requestAPI($json);              
            }
   
            elseif($postArr['MsgType'] == 'event' && $postArr['Event']=='user_enter_tempsession'){ //用户进入客服后马上回复，现在已失效,需要用户先发过消息
                $fromUsername = $postArr['FromUserName'];
                $content = '你好,回复1关注公众号，回复2获取官网链接';
                $data=array(
                    "touser"=>$fromUsername,
                    "msgtype"=>"text",
                    "text"=>array("content"=>$content)
                );
                $json = json_encode($data,JSON_UNESCAPED_UNICODE);  //php5.4+
                requestAPI($json);   
            }
   
   
            elseif($postArr['MsgType'] !== 'event'){        //用户发送其他内容,引导加客服
                $fromUsername = $postArr['FromUserName'];   //发送者openid
                $imgurl = "/miniapp300-300.png";            //客服微信二维码,相对路径
                $media_id = getMediaId($imgurl);            //获取图片消息的media_id
                $data=array(
                    "touser"=>$fromUsername,
                    "msgtype"=>"image",
                    "image"=>array("media_id"=>$media_id)
                );
                $json = json_encode($data,JSON_UNESCAPED_UNICODE);  //php5.4+
                requestAPI($json);
            }
            
            else{
                exit;
            }
            
        }else{
            echo "empty";
            exit;
        }
    }
    
    function requestAPI($json){
        $access_token = get_accessToken();
        /* 
         * POST发送https请求客服接口api
         */
        $url = "https://api.weixin.qq.com/cgi-bin/message/custom/send?access_token=".$access_token;
        //以'json'格式发送post的https请求
        $curl = curl_init();
        curl_setopt($curl, CURLOPT_URL, $url);
        curl_setopt($curl, CURLOPT_POST, 1); // 发送一个常规的Post请求
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE);
        if (!empty($json)){
            curl_setopt($curl, CURLOPT_POSTFIELDS,$json);
        }
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
        //curl_setopt($curl, CURLOPT_HTTPHEADER, $headers );
        $output = curl_exec($curl);
        if (curl_errno($curl)) {
            echo 'Errno'.curl_error($curl);//捕抓异常
        }
        curl_close($curl);
        if($output == 0){
            echo 'success';exit;
        }
    }       
    /* 调用微信api，获取access_token，有效期7200s*/
    function get_accessToken(){
    $url = 'https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=wx1231231321317&secret=12312313123122f376c6bf0e3a8'; //替换成自己的小程序id和secret
    @$weixin = file_get_contents($url);
    @$jsondecode = json_decode($weixin);
    @$array = get_object_vars($jsondecode);
    $token = $array['access_token'];
    return $token;
    }
    
    //获取上传图片的media_id
    function getMediaId($imgurl){
        $token=get_accessToken();
        $url = "https://api.weixin.qq.com/cgi-bin/media/upload?access_token={$token}&type=image";
        // echo $url;
        $ch1 = curl_init();
        $timeout = 10;
        $real_path = "{$_SERVER['DOCUMENT_ROOT']}$imgurl";//自动转成图片文件绝对路径,如果图片发送失败,检查PHP的$_SERVER['DOCUMENT_ROOT'的配置
        // echo $real_path;
        $data = array("media" =>  new CURLFile("{$real_path}"));//php5.6(含)以上版本使用此方法
        // var_dump($data);
        curl_setopt($ch1, CURLOPT_URL, $url);
        curl_setopt($ch1, CURLOPT_POST, 1);
        curl_setopt($ch1, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch1, CURLOPT_CONNECTTIMEOUT, $timeout);
        curl_setopt($ch1, CURLOPT_SSL_VERIFYPEER, FALSE);
        curl_setopt($ch1, CURLOPT_SSL_VERIFYHOST, false);
        curl_setopt($ch1, CURLOPT_POSTFIELDS, $data);
        $result = curl_exec($ch1);
        // echo $result;
        curl_close($ch1);
        if($result){
            $result = json_decode($result, true);
            return $result['media_id'];
        } else{
            return null;
        }
    }

?>

第二种是企业微信的微信客服，可以接入小程序、app、网页等地方。