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This article mainly introduces how to program HBase, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor with you to understand.

Using Eclipse to develop HBase applications

1. Create a new Java Project in Eclipse and name it HBaseTest, then right-click in Properties and select Java Build Path and Add External Jars to import the jar package under the HBase/lib directory.

2. Create a Conf folder under the root directory of the project, copy the hbase-site.xml file under HBase/Conf to this folder, right-select Properties- > Java BuildPath- > Libraries- > Add Class Folder, and then select the Conf folder.

Second, a brief introduction to HBaseJava API

1, HbaseConfiguration

Relationship: org.apache.hadoop.hbase.HBaseConfiguration

Purpose: HBase can be configured through this class

2, HBaseAdmin

Relationship: org.apache.hadoop.hbase.client.HBaseAdmin

Purpose: provides an interface to manage table information in the HBase database. It provides methods for creating tables, deleting tables, and so on.

3, HTableDescriptor

Relationship: org.apache.hadoop.hbase.client.HTableDescriptor

Function: contains the name of the table and its corresponding column family. The methods provided are

Void addFamily (HColumnDescriptor) add a column family

HColumnDescriptor removeFamily (byte [] column) removes a column family

Byte [] getName () gets the name of the table

Byte [] getValue (byte [] key) gets the value of the attribute

Void setValue (String key,Stringvalue) sets the value of the property

4, HColumnDescriptor

Relationship: org.apache.hadoop.hbase.client.HColumnDescriptor

Purpose: to maintain information about columns. The methods provided are

Byte [] getName () gets the name of the column family

Byte [] getValue () gets the value of the corresponding attribute

Void setValue (String key,String value) sets the value of the corresponding property

5, HTable

Relationship: org.apache.hadoop.hbase.client.HTable

Function: the user communicates with HBase table. This method is not thread-safe for update operations, and the write buffer may crash if multiple threads are started to try to communicate with a single HTable instance.

6, Put

Relationship: org.apache.hadoop.hbase.client.Put

Function: used to perform add operations on a single row

7, Get

Relationship: org.apache.hadoop.hbase.client.Get

Function: used to get information about a single row

8, Result

Relationship: org.apache.hadoop.hbase.client.Result

Purpose: stores the single-line value obtained after the Get or Scan operation.

9, ResultScanner

Relationship: Interface

Function: the interface through which the client gets the value.

3. HBase Java API simple instance import java.io.IOException;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.client.HBaseAdmin;import org.apache.hadoop.hbase.client.HTable;import org.apache.hadoop.hbase.client.Put;import org.apache.hadoop.hbase.client.Get;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;/* * @ author minglaihan * / public class HBaseTest {static Configuration cfg = HBaseConfiguration.create (); / / create a new table public static void create (String tableName, String columnFamily) throws Exception {HBaseAdmin admin = new HBaseAdmin (cfg) through HBaseAdmin HTableDescriptor If (admin.tableExists (tableName)) {System.out.println ("Table exist"); System.exit (0);} else {HTableDescriptor tableDescriptor = new HTableDescriptor (tableName); tableDescriptor.addFamily (new HColumnDescriptor (columnFamily)) Admin.createTable (tableDescriptor); System.out.println ("Table create success") }} / / add a piece of data to the existing table through HTable Put public static void put (String tableName,String row,String columnFamily,String column,String data) throws IOException {HTable table = new HTable (cfg, tableName); Put put = new Put (Bytes.toBytes (row)) Put.add (Bytes.toBytes (columnFamily), Bytes.toBytes (column), Bytes.toBytes (data)); table.put (put); System.out.println ("put success") } / / get the result set public static void get (String tableName,String row) throws IOException {HTable table = new HTable (cfg, tableName); Get get = new Get (Bytes.toBytes (row)); Result result = table.get (get); System.out.println ("get" + result) listed in the tableName table } / / get all the data information of the tableName table through HTable Scan public static void scan (String tableName) throws IOException {HTable table = new HTable (cfg, tableName); Scan scan = new Scan (); ResultScanner resultScanner = table.getScanner (scan) For (Result s:resultScanner) {System.out.println ("Scan" + resultScanner);}} public static boolean delete (String tableName) throws Exception {HBaseAdmin admin = new HBaseAdmin (cfg) If (admin.tableExists (tableName)) {try {admin.disableTable (tableName); admin.deleteTable (tableName) } catch (Exception e) {/ / TODO: handle exception e.printStackTrace (); return false;}} return true } public static void main (String [] args) {String tableName = "hbase_test"; String columnFamily = "C1"; try {HBaseTest.create (tableName, columnFamily); HBaseTest.put (tableName, "row1", columnFamily, "column1", "data1") HBaseTest.get (tableName, "row1"); HBaseTest.scan (tableName); if (HBaseTest.delete (tableName) = = true) {System.out.println ("delete table" + tableName+ "success") Catch (Exception e) {/ / TODO: handle exception e.printStackTrace ();}}

Screenshot of the running result commenting out the steps of Delete:

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