BAEL-3091: The Prototype Pattern in Java (changed code based on valid comments from a reader)

google-cloud/src/main/java/com/baeldung/google/cloud/storage/GoogleCloudStorage.java

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+package com.baeldung.google.cloud.storage;
+
+import com.google.api.gax.paging.Page;
+import com.google.auth.Credentials;
+import com.google.auth.oauth2.GoogleCredentials;
+import com.google.cloud.storage.*;
+import lombok.extern.slf4j.Slf4j;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.WritableByteChannel;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+/**
+ * Simple class for creating, reading and modifying text blobs on Google Cloud
+ */
+@Slf4j
+public class GoogleCloudStorage {
+
+    private Storage storage;
+    private Bucket bucket;
+
+    public static void main(String[] args) throws Exception {
+
+        // Use this variation to read the Google authorization JSON from the resources directory with a path
+        // and a project name.
+        GoogleCloudStorage googleCloudStorage =
+            new GoogleCloudStorage("google-cloud/src/main/resources/google_auth.json", "baeldung-cloud-tutorial");
+
+        // Bucket require globally unique names, so you'll probably need to change this
+        Bucket bucket = googleCloudStorage.getBucket("baeldung-1-bucket");
+
+        // Save a simple string
+        BlobId blobId = googleCloudStorage.saveString("my-first-blob", "Hi there!", bucket);
+
+        // Get it by blob id this time
+        String value = googleCloudStorage.getString(blobId);
+
+        log.info("Read data: {}", value);
+
+        googleCloudStorage.updateString(blobId, "Bye now!");
+
+        // Get the string by blob name
+        value = googleCloudStorage.getString("my-first-blob");
+
+        log.info("Read modified data: {}", value);
+
+
+    }
+
+
+    // Use path and project name
+    private GoogleCloudStorage(String pathToConfig, String projectId) throws IOException {
+        Credentials credentials = GoogleCredentials.fromStream(new FileInputStream(pathToConfig));
+        storage = StorageOptions.newBuilder().setCredentials(credentials).setProjectId(projectId).build().getService();
+    }
+
+    // Check for bucket existence and create if needed.
+    private Bucket getBucket(String bucketName) {
+        bucket = storage.get(bucketName);
+        if (bucket == null) {
+            System.out.println("Creating new bucket.");
+            bucket = storage.create(BucketInfo.of(bucketName));
+        }
+        return bucket;
+    }
+
+    // Save a string to a blob
+    private BlobId saveString(String blobName, String value, Bucket bucket) {
+        byte[] bytes = value.getBytes(UTF_8);
+        Blob blob = bucket.create(blobName, bytes);
+        return blob.getBlobId();
+    }
+
+
+    // get a blob by id
+    private String getString(BlobId blobId) {
+        Blob blob = storage.get(blobId);
+        return new String(blob.getContent());
+    }
+
+
+    // get a blob by name
+    private String getString(String name) {
+        Page<Blob> blobs = bucket.list();
+        for (Blob blob: blobs.getValues()) {
+            if (name.equals(blob.getName())) {
+                return new String(blob.getContent());
+            }
+        }
+        return "Blob not found";
+    }
+
+    // Update a blob
+    private void updateString(BlobId blobId, String newString) throws IOException {
+        Blob blob = storage.get(blobId);
+        if (blob != null) {
+            WritableByteChannel channel = blob.writer();
+            channel.write(ByteBuffer.wrap(newString.getBytes(UTF_8)));
+            channel.close();
+        }
+    }
+}

google-cloud/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>