https://blog.csdn.net/zhuyu19911016520/article/details/103930541/String sfilepath = appPath + '/' + apkName;
Map<PermissionGroup, PermissionStatus> permissions =
await PermissionHandler().requestPermissions([PermissionGroup.storage]);
if (permissions[PermissionGroup.storage] == PermissionStatus.granted) {
InstallPlugin.installApk(sfilepath, 'com.toppms.khapp')
.then((result) {
print('install apk $result');
}).catchError((error) {
print('install apk error: $error');
});
} else {
print('Permission request fail!');
}