HBase Connection using Java API
HBase is a column oriented database which stores its contents by column rather than by row. Instead of retrieving a record or row at a time, an entire column is retrieved and thus it becomes very powerful and efficient since data analytics is usually concerned with only one field or column of a record. The access becomes much faster, and much more relevant data can be extracted from the database in a shorter period of time.
A sample code for connecting HBase is given below.
package sample;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.client.Delete;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.util.Bytes;
public class HbaseTest {
private static Configuration conf = null;
/**
* Initialization
*/
static {
//String hbaseZookeeperQuorum = "bdcltvmserv04:2181";
String hbaseZookeeperQuorum = "quorum:2181";
String hbaseZookeeperClientPort = "2181";
conf = HBaseConfiguration.create();
conf.set("hbase.zookeeper.quorum",
hbaseZookeeperQuorum);
conf.set("hbase.zookeeper.property.clientPort",
hbaseZookeeperClientPort);
//conf.set("hbase.master", "bdcltvmserv08:60000");
}
/**
* Create a table
*/
public static void creatTable(String tableName, String[] familys)
throws Exception {
HBaseAdmin admin = new HBaseAdmin(conf);
if (admin.tableExists(tableName)) {
System.out.println("table already exists!");
} else {
HTableDescriptor tableDesc = new HTableDescriptor(tableName);
for (int i = 0; i < familys.length; i++) {
tableDesc.addFamily(new HColumnDescriptor(familys[i]));
}
admin.createTable(tableDesc);
System.out.println("create table " + tableName + " ok.");
}
}
/**
* Delete a table
*/
public static void deleteTable(String tableName) throws Exception {
try {
HBaseAdmin admin = new HBaseAdmin(conf);
admin.disableTable(tableName);
admin.deleteTable(tableName);
System.out.println("delete table " + tableName + " ok.");
} catch (MasterNotRunningException e) {
e.printStackTrace();
} catch (ZooKeeperConnectionException e) {
e.printStackTrace();
}
}
/**
* Put (or insert) a row
*/
public static void addRecord(String tableName, String rowKey,
String family, String qualifier, String value) throws Exception {
try {
HTable table = new HTable(conf, tableName);
Put put = new Put(Bytes.toBytes(rowKey));
put.add(Bytes.toBytes(family), Bytes.toBytes(qualifier),
Bytes.toBytes(value));
table.put(put);
System.out.println("insert recored " + rowKey + " to table "
+ tableName + " ok.");
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* Delete a row
*/
public static void delRecord(String tableName, String rowKey)
throws IOException {
HTable table = new HTable(conf, tableName);
List<Delete> list = new ArrayList<Delete>();
Delete del = new Delete(rowKey.getBytes());
list.add(del);
table.delete(list);
System.out.println("del recored " + rowKey + " ok.");
}
/**
* Get a row
*/
public static void getOneRecord(String tableName, String rowKey)
throws IOException {
HTable table = new HTable(conf, tableName);
Get get = new Get(rowKey.getBytes());
Result rs = table.get(get);
for (KeyValue kv : rs.raw()) {
System.out.print(new String(kv.getRow()) + " ");
System.out.print(new String(kv.getFamily()) + ":");
System.out.print(new String(kv.getQualifier()) + " ");
System.out.print(kv.getTimestamp() + " ");
System.out.println(new String(kv.getValue()));
}
}
/**
* Scan (or list) a table
*/
public static void getAllRecord(String tableName) {
try {
HTable table = new HTable(conf, tableName);
Scan s = new Scan();
ResultScanner ss = table.getScanner(s);
for (Result r : ss) {
for (KeyValue kv : r.raw()) {
System.out.print(new String(kv.getRow()) + " ");
System.out.print(new String(kv.getFamily()) + ":");
System.out.print(new String(kv.getQualifier()) + " ");
System.out.print(kv.getTimestamp() + " ");
System.out.println(new String(kv.getValue()));
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] agrs) {
try {
String tablename = "employee";
String[] familys = {"data"};
HbaseTest.creatTable(tablename, familys);
// add record zkb
HbaseTest.addRecord(tablename, "row1", "data", "city", "Banglore");
HbaseTest.addRecord(tablename, "row2", "data", "city", "Noida");
HbaseTest.addRecord(tablename, "row3", "data", "city", "Banglore");
HbaseTest.addRecord(tablename, "row4", "data", "city", "Noida");
HbaseTest.addRecord(tablename, "row5", "data", "city", "Noida");
HbaseTest.addRecord(tablename, "row6", "data", "city", "Trivandrum");
HbaseTest.addRecord(tablename, "row7", "data", "city", "Ernakulam");
HbaseTest.addRecord(tablename, "row8", "data", "city", "Ernakulam");
HbaseTest.addRecord(tablename, "row9", "data", "city", "Trivandrum");
HbaseTest.addRecord(tablename, "row10", "data", "city", "Trivandrum");
HbaseTest.addRecord(tablename, "row11", "data", "city", "Ernakulam");
System.out.println("===========show all record========");
HbaseTest.getAllRecord(tablename);
System.out.println("===========delete table========");
HbaseTest.deleteTable(tablename);
} catch (Exception e) {
e.printStackTrace();
}
}
}
Output
