/**
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hbase.archetypes.exemplars.shaded_client;
import java.io.IOException;
import java.util.Map.Entry;
import java.util.NavigableMap;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.NamespaceDescriptor;
import org.apache.hadoop.hbase.NamespaceNotFoundException;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Delete;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Table;
import org.apache.hadoop.hbase.util.Bytes;
/**
* Successful running of this application requires access to an active instance
* of HBase. For install instructions for a standalone instance of HBase, please
* refer to https://hbase.apache.org/book.html#quickstart
*/
public final class HelloHBase {
protected static final String MY_NAMESPACE_NAME = "myTestNamespace";
static final TableName MY_TABLE_NAME = TableName.valueOf("myTestTable");
static final byte[] MY_COLUMN_FAMILY_NAME = Bytes.toBytes("cf");
static final byte[] MY_FIRST_COLUMN_QUALIFIER
= Bytes.toBytes("myFirstColumn");
static final byte[] MY_SECOND_COLUMN_QUALIFIER
= Bytes.toBytes("mySecondColumn");
static final byte[] MY_ROW_ID = Bytes.toBytes("rowId01");
// Private constructor included here to avoid checkstyle warnings
private HelloHBase() {
}
public static void main(final String[] args) throws IOException {
final boolean deleteAllAtEOJ = true;
/**
* ConnectionFactory#createConnection() automatically looks for
* hbase-site.xml (HBase configuration parameters) on the system's
* CLASSPATH, to enable creation of Connection to HBase via ZooKeeper.
*/
try (Connection connection = ConnectionFactory.createConnection();
Admin admin = connection.getAdmin()) {
admin.getClusterStatus(); // assure connection successfully established
System.out.println("\n*** Hello HBase! -- Connection has been "
+ "established via ZooKeeper!!\n");
createNamespaceAndTable(admin);
System.out.println("Getting a Table object for [" + MY_TABLE_NAME
+ "] with which to perform CRUD operations in HBase.");
try (Table table = connection.getTable(MY_TABLE_NAME)) {
putRowToTable(table);
getAndPrintRowContents(table);
if (deleteAllAtEOJ) {
deleteRow(table);
}
}
if (deleteAllAtEOJ) {
deleteNamespaceAndTable(admin);
}
}
}
/**
* Invokes Admin#createNamespace and Admin#createTable to create a namespace
* with a table that has one column-family.
*
* @param admin Standard Admin object
* @throws IOException If IO problem encountered
*/
static void createNamespaceAndTable(final Admin admin) throws IOException {
if (!namespaceExists(admin, MY_NAMESPACE_NAME)) {
System.out.println("Creating Namespace [" + MY_NAMESPACE_NAME + "].");
admin.createNamespace(NamespaceDescriptor
.create(MY_NAMESPACE_NAME).build());
}
if (!admin.tableExists(MY_TABLE_NAME)) {
System.out.println("Creating Table [" + MY_TABLE_NAME.getNameAsString()
+ "], with one Column Family ["
+ Bytes.toString(MY_COLUMN_FAMILY_NAME) + "].");
admin.createTable(new HTableDescriptor(MY_TABLE_NAME)
.addFamily(new HColumnDescriptor(MY_COLUMN_FAMILY_NAME)));
}
}
/**
* Invokes Table#put to store a row (with two new columns created 'on the
* fly') into the table.
*
* @param table Standard Table object (used for CRUD operations).
* @throws IOException If IO problem encountered
*/
static void putRowToTable(final Table table) throws IOException {
table.put(new Put(MY_ROW_ID).addColumn(MY_COLUMN_FAMILY_NAME,
MY_FIRST_COLUMN_QUALIFIER,
Bytes.toBytes("Hello")).addColumn(MY_COLUMN_FAMILY_NAME,
MY_SECOND_COLUMN_QUALIFIER,
Bytes.toBytes("World!")));
System.out.println("Row [" + Bytes.toString(MY_ROW_ID)
+ "] was put into Table ["
+ table.getName().getNameAsString() + "] in HBase;\n"
+ " the row's two columns (created 'on the fly') are: ["
+ Bytes.toString(MY_COLUMN_FAMILY_NAME) + ":"
+ Bytes.toString(MY_FIRST_COLUMN_QUALIFIER)
+ "] and [" + Bytes.toString(MY_COLUMN_FAMILY_NAME) + ":"
+ Bytes.toString(MY_SECOND_COLUMN_QUALIFIER) + "]");
}
/**
* Invokes Table#get and prints out the contents of the retrieved row.
*
* @param table Standard Table object
* @throws IOException If IO problem encountered
*/
static void getAndPrintRowContents(final Table table) throws IOException {
Result row = table.get(new Get(MY_ROW_ID));
System.out.println("Row [" + Bytes.toString(row.getRow())
+ "] was retrieved from Table ["
+ table.getName().getNameAsString()
+ "] in HBase, with the following content:");
for (Entry<byte[], NavigableMap<byte[], byte[]>> colFamilyEntry
: row.getNoVersionMap().entrySet()) {
String columnFamilyName = Bytes.toString(colFamilyEntry.getKey());
System.out.println(" Columns in Column Family [" + columnFamilyName
+ "]:");
for (Entry<byte[], byte[]> columnNameAndValueMap
: colFamilyEntry.getValue().entrySet()) {
System.out.println(" Value of Column [" + columnFamilyName + ":"
+ Bytes.toString(columnNameAndValueMap.getKey()) + "] == "
+ Bytes.toString(columnNameAndValueMap.getValue()));
}
}
}
/**
* Checks to see whether a namespace exists.
*
* @param admin Standard Admin object
* @param namespaceName Name of namespace
* @return true If namespace exists
* @throws IOException If IO problem encountered
*/
static boolean namespaceExists(final Admin admin, final String namespaceName)
throws IOException {
try {
admin.getNamespaceDescriptor(namespaceName);
} catch (NamespaceNotFoundException e) {
return false;
}
return true;
}
/**
* Invokes Table#delete to delete test data (i.e. the row)
*
* @param table Standard Table object
* @throws IOException If IO problem is encountered
*/
static void deleteRow(final Table table) throws IOException {
System.out.println("Deleting row [" + Bytes.toString(MY_ROW_ID)
+ "] from Table ["
+ table.getName().getNameAsString() + "].");
table.delete(new Delete(MY_ROW_ID));
}
/**
* Invokes Admin#disableTable, Admin#deleteTable, and Admin#deleteNamespace to
* disable/delete Table and delete Namespace.
*
* @param admin Standard Admin object
* @throws IOException If IO problem is encountered
*/
static void deleteNamespaceAndTable(final Admin admin) throws IOException {
if (admin.tableExists(MY_TABLE_NAME)) {
System.out.println("Disabling/deleting Table ["
+ MY_TABLE_NAME.getNameAsString() + "].");
admin.disableTable(MY_TABLE_NAME); // Disable a table before deleting it.
admin.deleteTable(MY_TABLE_NAME);
}
if (namespaceExists(admin, MY_NAMESPACE_NAME)) {
System.out.println("Deleting Namespace [" + MY_NAMESPACE_NAME + "].");
admin.deleteNamespace(MY_NAMESPACE_NAME);
}
}
}