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CopyOldVersionOfObject.java
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CopyOldVersionOfObject.java
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/*
* Copyright 2020 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.
*/
package com.example.storage.object;
// [START storage_copy_file_archived_generation]
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
public class CopyOldVersionOfObject {
public static void copyOldVersionOfObject(
String projectId,
String bucketName,
String objectToCopy,
long generationToCopy,
String newObjectName) {
// The ID of your GCP project
// String projectId = "your-project-id";
// The ID of your GCS bucket
// String bucketName = "your-unique-bucket-name";
// The ID of the GCS object to copy an old version of
// String objectToCopy = "your-object-name";
// The generation of objectToCopy to copy
// long generationToCopy = 1579287380533984;
// What to name the new object with the old data from objectToCopy
// String newObjectName = "your-new-object";
Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();
// Optional: set a generation-match precondition to avoid potential race
// conditions and data corruptions. The request returns a 412 error if the
// preconditions are not met.
Storage.BlobTargetOption precondition;
if (storage.get(bucketName, newObjectName) == null) {
// For a target object that does not yet exist, set the DoesNotExist precondition.
// This will cause the request to fail if the object is created before the request runs.
precondition = Storage.BlobTargetOption.doesNotExist();
} else {
// If the destination already exists in your bucket, instead set a generation-match
// precondition. This will cause the request to fail if the existing object's generation
// changes before the request runs.
precondition =
Storage.BlobTargetOption.generationMatch(
storage.get(bucketName, newObjectName).getGeneration());
}
Storage.CopyRequest copyRequest =
Storage.CopyRequest.newBuilder()
.setSource(BlobId.of(bucketName, objectToCopy, generationToCopy))
.setTarget(BlobId.of(bucketName, newObjectName), precondition)
.build();
storage.copy(copyRequest);
System.out.println(
"Generation "
+ generationToCopy
+ " of object "
+ objectToCopy
+ " in bucket "
+ bucketName
+ " was copied to "
+ newObjectName);
}
}
// [END storage_copy_file_archived_generation]