googleworkspace · sqrrrl · Feb 23, 2022 · Jan 14, 2022 · Jan 14, 2022 · Jan 14, 2022
diff --git a/drive/snippets/drive_v2/src/main/java/DownloadFile.java b/drive/snippets/drive_v2/src/main/java/DownloadFile.java
@@ -0,0 +1,69 @@
+/* Copyright 2022 Google LLC
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.*/
+
+// [START drive_download_file]
+
+import com.google.api.client.googleapis.json.GoogleJsonResponseException;
+import com.google.api.client.http.HttpRequestInitializer;
+import com.google.api.client.http.javanet.NetHttpTransport;
+import com.google.api.client.json.gson.GsonFactory;
+import com.google.api.services.drive.Drive;
+import com.google.api.services.drive.DriveScopes;
+import com.google.auth.http.HttpCredentialsAdapter;
+import com.google.auth.oauth2.GoogleCredentials;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.Arrays;
+
+/* Class to demonstrate use-case of drive's download file. */
+public class DownloadFile {
+
+    /**
+     * Download a Document file in PDF format.
+     * @param realFileId file ID of any workspace document format file.
+     * @return byte array stream if successful, {@code null} otherwise.
+     * @throws IOException if service account credentials file not found.
+     */
+    private static ByteArrayOutputStream downloadFile(String realFileId) throws IOException{
+        /* Load pre-authorized user credentials from the environment.
+           TODO(developer) - See https://developers.google.com/identity for
+          guides on implementing OAuth2 for your application.*/
+        GoogleCredentials credentials = GoogleCredentials.getApplicationDefault().createScoped(Arrays.asList(DriveScopes.DRIVE_FILE));
+        HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(
+                credentials);
+
+        // Build a new authorized API client service.
+        Drive service = new Drive.Builder(new NetHttpTransport(),
+                GsonFactory.getDefaultInstance(),
+                requestInitializer)
+                .setApplicationName("Drive samples")
+                .build();
+
+        try {
+            OutputStream outputStream = new ByteArrayOutputStream();
+
+            service.files().get(realFileId)
+                    .executeMediaAndDownloadTo(outputStream);
+
+            return (ByteArrayOutputStream) outputStream;
+        }catch (GoogleJsonResponseException e) {
+            // TODO(developer) - handle error appropriately
+            System.err.println("Unable to move file: " + e.getDetails());
+            throw e;
+        }
+    }
+}
+// [END drive_download_file]