1. Table exists
package org.example;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
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 java.io.IOException;
public class TestDemo {
public static Connection connection=null;
public static Admin admin=null;
static {
try {
Configuration configuration = HBaseConfiguration.create();
configuration.set("hbase.rootdir", "hdfs://192.168.170.80:8020/hbase");
configuration.set("hbase.zookeeper.quorum","hadooplyf316");
connection= ConnectionFactory.createConnection(configuration);
admin = connection.getAdmin();
} catch (IOException e) {
e.printStackTrace();
}
}
//Determine whether the table exists
public static boolean isTableExist(String tableName) throws IOException {
boolean exists = admin.tableExists(TableName.valueOf(tableName));
return exists;
}
public static void close(){
if (admin!=null){
try {
admin.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (connection!=null){
try {
connection.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) throws IOException {
//System.out.println(isTableExist("Student"));
if(isTableExist("Student")){
System.out.println("Table exists");
}
else{
System.out.println("does not exist");
}
//Close the resource
close();
}
}
2.scan
package org.example;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.*;
import java.io.IOException;
import java.util.Scanner;
public class scan {
public static Configuration configuration;
public static Connection connection;
public static Admin admin;
// establish connection
public static void init() {
configuration = HBaseConfiguration.create();
configuration.set("hbase.rootdir", "hdfs://192.168.170.80:8020/hbase");
configuration.set("hbase.zookeeper.quorum","hadooplyf316");
try {
connection = ConnectionFactory.createConnection(configuration);
admin = connection.getAdmin();
} catch (IOException e) {
e.printStackTrace();
}
}
// close connection
public static void close() {
try {
if (admin != null) {
admin.close();
}
if (null != connection) {
connection.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
/**
*
* Find table information based on table name
*
*/
public static void getData(String tableName) throws IOException {
init();
Table table = connection.getTable(TableName.valueOf(tableName));
Scan scan = new Scan();
ResultScanner scanner = table.getScanner(scan);
for (Result result : scanner)
{
showCell((result));
}
close();
}
/**
*
* Formatted output
*
* @param result
*
*/
public static void showCell(Result result) {
Cell[] cells = result.rawCells();
for (Cell cell : cells) {
System.out.println("RowName(row key):" + new String(CellUtil.cloneRow(cell)) + " ");
System.out.println("Timetamp(timestamp):" + cell.getTimestamp() + " ");
System.out.println("column Family:" + new String(CellUtil.cloneFamily(cell)) + " ");
System.out.println("column Name:" + new String(CellUtil.cloneQualifier(cell)) + " ");
System.out.println("value:(value)" + new String(CellUtil.cloneValue(cell)) + " ");
System.out.println();
}
}
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
scan t = new scan();
System.out.println("Please enter the name of the table you want to view");
Scanner scan = new Scanner(System.in);
String tableName = scan.nextLine();
System.out.println("The information is as follows:");
t.getData(tableName);
}
}
3. Create table
package org.example;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.*;
import org.apache.hadoop.hbase.util.Bytes;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;
import java.io.IOException;
public class TableAdminTest {
private Connection connection;
private Admin admin;
@BeforeTest
public void beforeTest() throws IOException {
// 1. Use HbaseConfiguration.create() to create Hbase configuration
Configuration configuration = HBaseConfiguration.create();
configuration.set("hbase.rootdir", "hdfs://192.168.170.80:8020/hbase");
configuration.set("hbase.zookeeper.quorum","hadooplyf316");
// 2. Use ConnectionFactory.createConnection() to create an Hbase connection
connection = ConnectionFactory.createConnection(configuration);
// 3. To create a table, you need to obtain the admin management object based on the Hbase connection.
// To create a table or delete a table, you need to connect to HMaster, so you need an admin object.
admin = connection.getAdmin();
}
@Test
public void createTableTest() throws IOException {
TableName tableName = TableName.valueOf("test");
// 1. Determine whether the table exists
if(admin.tableExists(tableName)) {
// a) exists, then exit
return;
}
// Build table
// 2. Use TableDescriptorBuilder.newBuilder to build the table description builder
// TableDescriptor: Table descriptor, describing how many columns this table has and other attributes can be configured here
TableDescriptorBuilder tableDescriptorBuilder = TableDescriptorBuilder.newBuilder(tableName);
// 3. Use ColumnFamilyDescriptorBuilder.newBuilder to build the column description builder
// Creating a column also requires a column descriptor, which needs to be built with a ColumnFamilyDescriptor
// A tool class is often used: Bytes (Bytes tool class under the hbase package)
// This tool class can convert string, long, and double types into byte[] arrays
// You can also convert the byte[] array to the specified type
ColumnFamilyDescriptorBuilder columnFamilyDescriptorBuilder = ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes("C1"));
// 4. Construct column description and table description
ColumnFamilyDescriptor cfDes = columnFamilyDescriptorBuilder.build();
// Establish a relationship between tables and columns
tableDescriptorBuilder.setColumnFamily(cfDes);
TableDescriptor tableDescriptor = tableDescriptorBuilder.build();
admin.createTable(tableDescriptor);
}
@Test
public void deleteTableTest() throws IOException {
TableName tableName = TableName.valueOf("t");
if(admin.tableExists(tableName)) {
admin.disableTable(tableName);
admin.deleteTable(tableName);
}
}
@AfterTest
public void afterTest() throws IOException {
admin.close();
connection.close();
}
}
4.List
package org.example;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.*;
import java.io.IOException;
public class list {
public static Configuration configuration;
public static Connection connection;
public static Admin admin;
/**
* establish connection
*/
public static void init() {
configuration = HBaseConfiguration.create();
configuration.set("hbase.rootdir", "hdfs://192.168.170.80:8020/hbase");
configuration.set("hbase.zookeeper.quorum","hadooplyf316");
try {
connection = ConnectionFactory.createConnection(configuration);
admin = connection.getAdmin();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* Close the connection
*/
public static void close() {
try {
if (admin != null) {
admin.close();
}
if (null != connection) {
connection.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
/**
*
* View existing tables through the method listTables()
*
* @throwsIOException
*
*/
public static void listTables() throws IOException {
init();
HTableDescriptor hTableDescriptors[] = admin.listTables();
for (HTableDescriptor hTableDescriptor : hTableDescriptors) {
System.out.println(hTableDescriptor.getNameAsString());
}
close();
}
public static void main(String[] args) {
list t = new list();
try {
System.out.println("The following is the table information stored in the Hbase database");
t.listTables();
} catch (IOException e) {
e.printStackTrace();
}
}
}
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