/
ComposeObject.java
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/
ComposeObject.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_compose_file]
import com.google.cloud.storage.Blob;
import com.google.cloud.storage.BlobInfo;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
public class ComposeObject {
public static void composeObject(
String bucketName,
String firstObjectName,
String secondObjectName,
String targetObjectName,
String projectId) {
// 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 first GCS object to compose
// String firstObjectName = "your-first-object-name";
// The ID of the second GCS object to compose
// String secondObjectName = "your-second-object-name";
// The ID to give the new composite object
// String targetObjectName = "new-composite-object-name";
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, targetObjectName) == 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, targetObjectName).getGeneration());
}
Storage.ComposeRequest composeRequest =
Storage.ComposeRequest.newBuilder()
// addSource takes varargs, so you can put as many objects here as you want, up to the
// max of 32
.addSource(firstObjectName, secondObjectName)
.setTarget(BlobInfo.newBuilder(bucketName, targetObjectName).build())
.setTargetOptions(precondition)
.build();
Blob compositeObject = storage.compose(composeRequest);
System.out.println(
"New composite object "
+ compositeObject.getName()
+ " was created by combining "
+ firstObjectName
+ " and "
+ secondObjectName);
}
}
// [END storage_compose_file]