package client;
// cc ScanExample Example using a scanner to access data in a table
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
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.client.Table;
import org.apache.hadoop.hbase.util.Bytes;
import util.HBaseHelper;
public class ScanExample {
public static void main(String[] args) throws IOException {
Configuration conf = HBaseConfiguration.create();
HBaseHelper helper = HBaseHelper.getHelper(conf);
helper.dropTable("testtable");
helper.createTable("testtable", "colfam1", "colfam2");
System.out.println("Adding rows to table...");
// Tip: Remove comment below to enable padding, adjust start and stop
// row, as well as columns below to match. See scan #5 comments.
helper.fillTable("testtable", 1, 100, 100, /* 3, false, */ "colfam1", "colfam2");
Connection connection = ConnectionFactory.createConnection(conf);
Table table = connection.getTable(TableName.valueOf("testtable"));
System.out.println("Scanning table #1...");
// vv ScanExample
Scan scan1 = new Scan(); // co ScanExample-1-NewScan Create empty Scan instance.
ResultScanner scanner1 = table.getScanner(scan1); // co ScanExample-2-GetScanner Get a scanner to iterate over the rows.
for (Result res : scanner1) {
System.out.println(res); // co ScanExample-3-Dump Print row content.
}
scanner1.close(); // co ScanExample-4-Close Close scanner to free remote resources.
// ^^ ScanExample
System.out.println("Scanning table #2...");
// vv ScanExample
Scan scan2 = new Scan();
scan2.addFamily(Bytes.toBytes("colfam1")); // co ScanExample-5-AddColFam Add one column family only, this will suppress the retrieval of "colfam2".
ResultScanner scanner2 = table.getScanner(scan2);
for (Result res : scanner2) {
System.out.println(res);
}
scanner2.close();
// ^^ ScanExample
System.out.println("Scanning table #3...");
// vv ScanExample
Scan scan3 = new Scan();
scan3.addColumn(Bytes.toBytes("colfam1"), Bytes.toBytes("col-5")).
addColumn(Bytes.toBytes("colfam2"), Bytes.toBytes("col-33")). // co ScanExample-6-Build Use fluent pattern to add specific details to the Scan.
setStartRow(Bytes.toBytes("row-10")).
setStopRow(Bytes.toBytes("row-20"));
ResultScanner scanner3 = table.getScanner(scan3);
for (Result res : scanner3) {
System.out.println(res);
}
scanner3.close();
// ^^ ScanExample
System.out.println("Scanning table #4...");
// vv ScanExample
Scan scan4 = new Scan();
scan4.addColumn(Bytes.toBytes("colfam1"), Bytes.toBytes("col-5")). // co ScanExample-7-Build Only select one column.
setStartRow(Bytes.toBytes("row-10")).
setStopRow(Bytes.toBytes("row-20"));
ResultScanner scanner4 = table.getScanner(scan4);
for (Result res : scanner4) {
System.out.println(res);
}
scanner4.close();
// ^^ ScanExample
System.out.println("Scanning table #5...");
// vv ScanExample
Scan scan5 = new Scan();
// ^^ ScanExample
// When using padding above, use "col-005", and "row-020", "row-010".
// vv ScanExample
scan5.addColumn(Bytes.toBytes("colfam1"), Bytes.toBytes("col-5")).
setStartRow(Bytes.toBytes("row-20")).
setStopRow(Bytes.toBytes("row-10")).
setReversed(true); // co ScanExample-8-Build One column scan that runs in reverse.
ResultScanner scanner5 = table.getScanner(scan5);
for (Result res : scanner5) {
System.out.println(res);
}
scanner5.close();
// ^^ ScanExample
table.close();
connection.close();
helper.close();
}
}