code: public void downloadFile(String bucketName, String srcFilename, Path destFilePath)
        throws IOException {
      // [START storage_download_file]
      // The name of the bucket to access
      // String bucketName = "my-bucket";
  
      // The name of the remote file to download
      // String srcFilename = "file.txt";
  
      // The path to which the file should be downloaded
      // Path destFilePath = Paths.get("/local/path/to/file.txt");
  
      // Instantiate a Google Cloud Storage client
      Storage storage = StorageOptions.getDefaultInstance().getService();
  
      // Get specific file from specified bucket
      Blob blob = storage.get(BlobId.of(bucketName, srcFilename));
  
      // Download file to specified path
      blob.downloadTo(destFilePath);
      // [END storage_download_file]
    }
docs: Example of downloading a file.