Hbase基本DDLDMLDQLAPI

• 生成conf -> 生成admin

Configuration cOnf= HBaseConfiguration.create();
HBaseAdmin admin = new HBaseAdmin(conf);


• 生成tableName -> 生成tableDescriptor

TableName tableName = TableName.valueOf("test");
HTableDescriptor tableDescriptor = new HTableDescriptor(tableName);


• 生成columnDescriptor（列族）-> 加入到tableDescriptor

tableDescriptor.addFamily(columnDescriptor);


• tableDescriptor -> admin生成table

admin.createTable(tableDescriptor);
DML

• conf & tableName -> 生成 table ，用于 DML 和 DQL

HTable table = new HTable(conf, tableName);


• 生成 row -> 生成put ，Hbase中传入传出数据库中的值用的都是byte[] , 要注意与String类型转换

byte[] row = Bytes.toBytes("row1");
Put put = new Put(row);


• 生成 想添加的val 以及它所在 列族 和 列 -> 加入到 put

byte[] colfam = Bytes.toBytes("data");
byte[] col = Bytes.toBytes(String.valueOf(1));
byte[] val = Bytes.toBytes("value1");
put.add(colfam, col, val);


• put -> table put

table.put(put);
DQL

get

• 生成 row -> 生成get

byte[] row = Bytes.toBytes("row1");
Get get = new Get(row);


• get -> table getResult 生成 result

Result result = table.get(get);


• 生成 查询的 列族 和 列 -> result getValue

byte[] colfam = Bytes.toBytes("data");
byte[] col = Bytes.toBytes(String.valueOf(1));
System.out.println("get value is " + Bytes.toString(result.getValue(colfam, col)));


scan

• 生成scan -> table getScanner 生成 ResultScanner。

Scan scan = new Scan();
ResultScanner scanner = table.getScanner(scan);


• ResultScanner可以理解为Result数组，遍历生成要查询的列族和列 -> result getValue

int i = 0;
for (Result scanresult : scanner) {
byte[] scancol = Bytes.toBytes(String.valueOf(++i));
System.out.println("scan value is " + Bytes.toString(scanresult.getValue(colfam, scancol)));
}


注意： HBaseAdmin,HTable,ResultScanner 对象最后都要close()

package ExampleClient;
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.MasterNotRunningException;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
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 ExampleClient {
public static void main(String[] args) throws MasterNotRunningException, ZooKeeperConnectionException, IOException {
// TODO Auto-generated method stub
Configuration cOnf= HBaseConfiguration.create();
HBaseAdmin admin = new HBaseAdmin(conf);
try {
TableName tableName = TableName.valueOf("test");
HTableDescriptor tableDescriptor = new HTableDescriptor(tableName);
HColumnDescriptor columnDescriptor = new HColumnDescriptor("data");
tableDescriptor.addFamily(columnDescriptor);
admin.createTable(tableDescriptor);
HTable table = new HTable(conf, tableName);
try {
for (int i = 1; i <= 3; ++i) {
byte[] row = Bytes.toBytes("row" + i);
Put put = new Put(row);
byte[] colfam = Bytes.toBytes("data");
byte[] col = Bytes.toBytes(String.valueOf(i));
byte[] val = Bytes.toBytes("value" + i);
put.add(colfam, col, val);
table.put(put);
}
byte[] row = Bytes.toBytes("row1");
Get get = new Get(row);
Result result = table.get(get);
byte[] colfam = Bytes.toBytes("data");
byte[] col = Bytes.toBytes(String.valueOf(1));
System.out.println("get result is " + Bytes.toString(result.getValue(colfam, col)));
Scan scan = new Scan();
ResultScanner scanner = table.getScanner(scan);
try {
int i = 0;
for (Result scanresult : scanner) {
byte[] scancol = Bytes.toBytes(String.valueOf(++i));
System.out.println("scan result is " + Bytes.toString(scanresult.getValue(colfam, scancol)));
}
} finally {
// TODO: handle finally clause
scanner.close();
}
} finally {
// TODO: handle finally clause
table.close();
}
} finally {
// TODO: handle finally clause
admin.close();
}
}
}