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Merge remote-tracking branch 'dpe/main' into cbt-examples-java/hello-world
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  • bigtable/hbase/snippets/src/main/java/com/example/cloud/bigtable/helloworld

‎bigtable/hbase/snippets/src/main/java/com/example/cloud/bigtable/helloworld/HelloWorld.java‎

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/**
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* Copyright 2016 Google Inc. All Rights Reserved.
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*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.cloud.bigtable.helloworld;
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// [START bigtable_hw_imports_hbase]
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import com.google.cloud.bigtable.hbase.BigtableConfiguration;
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import org.apache.hadoop.hbase.HColumnDescriptor;
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import org.apache.hadoop.hbase.HTableDescriptor;
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import org.apache.hadoop.hbase.TableName;
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import org.apache.hadoop.hbase.client.Admin;
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import org.apache.hadoop.hbase.client.Connection;
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import org.apache.hadoop.hbase.client.Get;
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import org.apache.hadoop.hbase.client.Put;
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import org.apache.hadoop.hbase.client.Result;
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import org.apache.hadoop.hbase.client.ResultScanner;
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import org.apache.hadoop.hbase.client.Scan;
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import org.apache.hadoop.hbase.client.Table;
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import org.apache.hadoop.hbase.util.Bytes;
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import java.io.IOException;
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// [END bigtable_hw_imports_hbase]
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/**
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* A minimal application that connects to Cloud Bigtable using the native HBase API and performs
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* some basic operations.
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*/
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public class HelloWorld {
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// Refer to table metadata names by byte array in the HBase API
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private static final byte[] TABLE_NAME = Bytes.toBytes("Hello-Bigtable");
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private static final byte[] COLUMN_FAMILY_NAME = Bytes.toBytes("cf1");
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private static final byte[] COLUMN_NAME = Bytes.toBytes("greeting");
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// Write some friendly greetings to Cloud Bigtable
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private static final String[] GREETINGS = {
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"Hello World!", "Hello Cloud Bigtable!", "Hello HBase!"
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};
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/** Connects to Cloud Bigtable, runs some basic operations and prints the results. */
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private static void doHelloWorld(String projectId, String instanceId) {
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// [START bigtable_hw_connect_hbase]
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// Create the Bigtable connection, use try-with-resources to make sure it gets closed
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try (Connection connection = BigtableConfiguration.connect(projectId, instanceId)) {
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// The admin API lets us create, manage and delete tables
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Admin admin = connection.getAdmin();
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// [END bigtable_hw_connect_hbase]
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try {
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// [START bigtable_hw_create_table_hbase]
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// Create a table with a single column family
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HTableDescriptor descriptor = new HTableDescriptor(TableName.valueOf(TABLE_NAME));
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descriptor.addFamily(new HColumnDescriptor(COLUMN_FAMILY_NAME));
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print("Create table " + descriptor.getNameAsString());
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admin.createTable(descriptor);
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// [END bigtable_hw_create_table_hbase]
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// [START bigtable_hw_write_rows_hbase]
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// Retrieve the table we just created so we can do some reads and writes
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Table table = connection.getTable(TableName.valueOf(TABLE_NAME));
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// Write some rows to the table
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print("Write some greetings to the table");
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for (int i = 0; i < GREETINGS.length; i++) {
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// Each row has a unique row key.
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//
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// Note: This example uses sequential numeric IDs for simplicity, but
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// this can result in poor performance in a production application.
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// Since rows are stored in sorted order by key, sequential keys can
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// result in poor distribution of operations across nodes.
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//
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// For more information about how to design a Bigtable schema for the
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// best performance, see the documentation:
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//
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// https://cloud.google.com/bigtable/docs/schema-design
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String rowKey = "greeting" + i;
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// Put a single row into the table. We could also pass a list of Puts to write a batch.
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Put put = new Put(Bytes.toBytes(rowKey));
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put.addColumn(COLUMN_FAMILY_NAME, COLUMN_NAME, Bytes.toBytes(GREETINGS[i]));
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table.put(put);
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}
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// [END bigtable_hw_write_rows_hbase]
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// [START bigtable_hw_get_by_key_hbase]
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// Get the first greeting by row key
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String rowKey = "greeting0";
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Result getResult = table.get(new Get(Bytes.toBytes(rowKey)));
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String greeting = Bytes.toString(getResult.getValue(COLUMN_FAMILY_NAME, COLUMN_NAME));
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System.out.println("Get a single greeting by row key");
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System.out.printf("\t%s = %s\n", rowKey, greeting);
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// [END bigtable_hw_get_by_key_hbase]
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// [START bigtable_hw_scan_all_hbase]
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// Now scan across all rows.
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Scan scan = new Scan();
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print("Scan for all greetings:");
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ResultScanner scanner = table.getScanner(scan);
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for (Result row : scanner) {
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byte[] valueBytes = row.getValue(COLUMN_FAMILY_NAME, COLUMN_NAME);
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System.out.println('\t' + Bytes.toString(valueBytes));
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}
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// [END bigtable_hw_scan_all_hbase]
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// [START bigtable_hw_delete_table_hbase]
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// Clean up by disabling and then deleting the table
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print("Delete the table");
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admin.disableTable(table.getName());
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admin.deleteTable(table.getName());
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// [END bigtable_hw_delete_table_hbase]
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} catch (IOException e) {
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if (admin.tableExists(TableName.valueOf(TABLE_NAME))) {
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print("Cleaning up table");
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admin.disableTable(TableName.valueOf(TABLE_NAME));
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admin.deleteTable(TableName.valueOf(TABLE_NAME));
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}
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throw e;
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}
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} catch (IOException e) {
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System.err.println("Exception while running HelloWorld: " + e.getMessage());
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e.printStackTrace();
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System.exit(1);
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}
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System.exit(0);
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}
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private static void print(String msg) {
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System.out.println("HelloWorld: " + msg);
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}
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public static void main(String[] args) {
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// Consult system properties to get project/instance
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String projectId = requiredProperty("bigtable.projectID");
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String instanceId = requiredProperty("bigtable.instanceID");
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doHelloWorld(projectId, instanceId);
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}
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private static String requiredProperty(String prop) {
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String value = System.getProperty(prop);
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if (value == null) {
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throw new IllegalArgumentException("Missing required system property: " + prop);
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}
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return value;
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}
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}

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