企业微信获取code

1. String url="https://open.weixin.qq.com/connect/oauth2/authorize?appid="+AuthUtil.APPID
2.  
   +"&redirect_uri="+URLEncoder.encode(backUrl)
3.  
   +"&response_type=code"
4.  
   +"&scope=snsapi_userinfo"
5.  
   +"&state=STATE#wechat_redirect";