[안드로이드] Android P (9.0) Error. CLEARTEXT communication 'IP' to not permitted by network security policy

에러발생 원인

안드로이드 P 버전(9.0) 에서 'HTTP' 를 사용하면 발생.

- java.net.UnknownServiceException : 

CLEARTEXT communication to xx.xxx.xxx.xx not permitted by network security policy

- java.io.IOException: Cleartext HTTP traffic to www.google.com not permitted

해결방법

1. AndroidManifest.xml 수정

android:usesCleartextTraffic="true" 추가

    <application
        ...
        android:usesCleartextTraffic="true"
        ...>

2. HTTPS 사용