package client;
// cc GetListExample Example of retrieving data from HBase using lists of Get instances
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.util.Bytes;
import util.HBaseHelper;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class GetListExample {
public static void main(String[] args) throws IOException {
Configuration conf = HBaseConfiguration.create();
HBaseHelper helper = HBaseHelper.getHelper(conf);
if (!helper.existsTable("testtable")) {
helper.createTable("testtable", "colfam1");
}
HTable table = new HTable(conf, "testtable");
// vv GetListExample
byte[] cf1 = Bytes.toBytes("colfam1");
byte[] qf1 = Bytes.toBytes("qual1");
byte[] qf2 = Bytes.toBytes("qual2"); // co GetListExample-1-Prepare Prepare commonly used byte arrays.
byte[] row1 = Bytes.toBytes("row1");
byte[] row2 = Bytes.toBytes("row2");
List<Get> gets = new ArrayList<Get>(); // co GetListExample-2-CreateList Create a list that holds the Get instances.
Get get1 = new Get(row1);
get1.addColumn(cf1, qf1);
gets.add(get1);
Get get2 = new Get(row2);
get2.addColumn(cf1, qf1); // co GetListExample-3-AddGets Add the Get instances to the list.
gets.add(get2);
Get get3 = new Get(row2);
get3.addColumn(cf1, qf2);
gets.add(get3);
Result[] results = table.get(gets); // co GetListExample-4-DoGet Retrieve rows with selected columns from HBase.
System.out.println("First iteration...");
for (Result result : results) {
String row = Bytes.toString(result.getRow());
System.out.print("Row: " + row + " ");
byte[] val = null;
if (result.containsColumn(cf1, qf1)) { // co GetListExample-5-GetValue1 Iterate over results and check what values are available.
val = result.getValue(cf1, qf1);
System.out.println("Value: " + Bytes.toString(val));
}
if (result.containsColumn(cf1, qf2)) {
val = result.getValue(cf1, qf2);
System.out.println("Value: " + Bytes.toString(val));
}
}
System.out.println("Second iteration...");
for (Result result : results) {
for (KeyValue kv : result.raw()) {
System.out.println("Row: " + Bytes.toString(kv.getRow()) + // co GetListExample-6-GetValue2 Iterate over results again, printing out all values.
" Value: " + Bytes.toString(kv.getValue()));
}
}
// ^^ GetListExample
}
}