需要加上

<?xml?version="1.0"?encoding="utf-8"?>
<network-security-config>
????<domain-config>
????????<domain?includeSubdomains="true">example.com</domain>
????????<pin-set?expiration="2018-01-01">
????????????<pin?digest="SHA-256">7HIpactkIAq2Y49orFOOQKurWxmmSFZhBCoQYcRhJ3Y=</pin>
????????????<!--?backup?pin?-->
????????????<pin?digest="SHA-256">fwza0LRMXouZHRC8Ei+4PyuldPDcf3UKgO/04cDM1oE=</pin>
????????</pin-set>
????</domain-config>
</network-security-config>

，這是res/xml/network_security_config.xml。自己新建xml目錄，加上上述文件。在AndroidManifest文件的application中加上

android:networkSecurityConfig="@xml/network_security_config"

應該是權限的問題。