1.检查所需的权限是否给全。
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" /> <uses-permission android:name="android.permission.WRITE_SETTINGS" tools:ignore="ProtectedPermissions" /> <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" tools:ignore="ProtectedPermissions" />
2.配置文件AndroidManifest.xml增加一段代码
android:requestLegacyExternalStorage="true"
原文：https://www.cnblogs.com/niupi/p/14979836.html