W/System.err: java.net.UnknownServiceException

錯誤：

W/System.err: java.net.UnknownServiceException: CLEARTEXT communication to api.qingyunke.com not permitted by network security policy
        at okhttp3.internal.connection.RealConnection.connect(RealConnection.java:164)
        at okhttp3.internal.connection.ExchangeFinder.findConnection(ExchangeFinder.java:224)
W/System.err:     at okhttp3.internal.connection.ExchangeFinder.findHealthyConnection(ExchangeFinder.java:108)
        at okhttp3.internal.connection.ExchangeFinder.find(ExchangeFinder.java:88)
        at okhttp3.internal.connection.Transmitter.newExchange(Transmitter.java:169)
        at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:41)
        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)
        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117)
W/System.err:     at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:94)
        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)
        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117)
        at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93)
        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)
        at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:88)
W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)
W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117)
        at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:229)
        at okhttp3.RealCall$AsyncCall.execute(RealCall.java:172)
        at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:764)

原因：新的保護機制對於僅使用安全通信的應用，Android 6.0 Marshmallow（API 級別 23）引入了兩種機制來解決回退到明文通信的問題：(1) 在生產/安裝庫中，禁止明文通信(2) 在開發/QA 期間，在遇到任何非 TLS/SSL 通信時，予以記錄或者觸發崩潰。

解決辦法：AndroidManifest.xml 文件，在 application 元素中添加：

 android:usesCleartextTraffic="true"