数据库连接非ip，是域名的情况下

host, port, err := net.SplitHostPort(host)
                // net.ParseIP(host)中host如果是域名，则会被修改为localhost
		if err != nil || net.ParseIP(host) == nil {
			c.host = hostDef
		} else {
			c.host = host
		}
		tmpPort, err := strconv.Atoi(port)
		if err != nil {
			c.port = portDef
		} else {
			c.port = int32(tmpPort)
		}

net包里，解析IP和解析域名的函数不是一个，解析IP是用net.ParseIP函数，解析域名是用net.ResolveIPAddr函数，如下代码。

	var ip net.IP
	//host, port, err := net.SplitHostPort("127.0.0.1:5236")
	host, port, _ := net.SplitHostPort("www.baidu.com:5236")
	fmt.Println(host, port)
	ip = net.ParseIP(host)
	if ip == nil {
		var addr, _ = net.ResolveIPAddr("ip", host)
		if addr == nil {
			fmt.Println("Invalid address")
		} else {
			ip = net.ParseIP(addr.String())
			fmt.Println("The address is", ip.String())
		}
	} else {
		fmt.Println("The address is", ip.String())
	}
}

运行的结果是