localhost and 127.0.0.1 are both ways of saying 'the current machine'. So localhost on your PC is the PC and localhost on the android is the phone. Since your phone isn't running a webserver of course it will refuse the connection.
You need to get the IP address of your machine (use ipconfig on windows to find out) and use that instead of 127.0.0.1. This may still not working depending on how your network/firewalls are set up. But that is a completely different topic.
Since you have not specified you are connected to a server from the device or emulator so I guess you are using your application in the emulator.
If you are referring your localhost on your system from the Android emulator then you have to use http://10.0.2.2:8080/ Because Android emulator runs in a Virtual Machine therefore here 127.0.0.1 or localhost will be emulator's own loopback address.
If you are using localhost in your url and testing your application in emulator , simply you can replace system's ip address for localhost in the URL.or you can use 10.0.2.2 instead of localhost.
Replacing localhost with 10.0.2.2 is correct, but you can alsor replace localhost with your physical machine's ip(it is better for debug purposes).
Ofc, if ip is provided by dhcp you would have to change it each time...
1.Firstly i was checked my local ip. goto command mode>> And write ipconfig.
Example: Windows 10>> search cmd>>then Write ipconfig .
2. Then get your local ip information >>>
3.Use give your localhost ip and virtual box ip. You need to use virtual box ip for genymotion.Check below screenshot. You can you below any ip under virtualbox host network