由于Android系统对用户权限有限制，未经授权的应用程序不能直接访问设备标识符（如IMEI）。为了解决这个问题，需要在应用程序中请求相应的权限，如READ_PHONE_STATE权限，以获取设备标识符。以下是一个示例代码片段，阐明了如何请求READ_PHONE_STATE权限：

if (ContextCompat.checkSelfPermission(thisActivity, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) { // Permission is not granted // Should we show an explanation? if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity, Manifest.permission.READ_PHONE_STATE)) { // Show an explanation to the user asynchronously -- don't block // this thread waiting for the user's response! After the user // sees the explanation, try again to request the permission. } else { // No explanation needed; request the permission ActivityCompat.requestPermissions(thisActivity, new String[]{Manifest.permission.READ_PHONE_STATE}, MY_PERMISSIONS_REQUEST_READ_PHONE_STATE);

    // MY_PERMISSIONS_REQUEST_READ_PHONE_STATE is an
    // app-defined int constant. The callback method gets the
    // result of the request.
}

} else { // Permission has already been granted }

在上面的代码中，对应用程序进行了检查，看是否已获得所请求的权限，如果没有，则将向用户显示请求权限的对话框并等待用户响应。如果用户授予了权限，则可以继续使用相关的API来访问设备标识符。