Android创建文件失败，导致下载文件失败的问题

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"