string(248) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E5%A6%82%E4%BD%95%E7%90%86%E8%A7%A3%E7%B3%BB%E7%BB%9F%E9%9B%86%E6%88%90%E7%9A%84%E6%A6%82%E5%BF%B5 => Received HTTP code 403 from proxy after CONNECT"
如何理解系统集成的概念
