code: function getUri(url) {
      let uriObj = url_opera.parse(url);
  
      let uri = url;
      let hostname = uriObj.hostname;
      let ip = config.hosts && config.hosts[hostname];
  
      // 如果有hosts的配置，且有对应域名的IP，则更改uri中的域名为IP
      if (ip) {
        let protocol = uriObj.protocol + '//';
  
        uri = url.replace(protocol + hostname, protocol + ip);
      }
  
      return {
        uri: uri,
        hostname: hostname,
        host: uriObj.host
      }
    }
docs: 根据当前host配置，生成正确的URL
  @param  {url} url    当前请求的URL
  @return {Object}     返回请求的正确URL及uri