Hbase->mapreduce->hbase

HBase expands the MapReduce API to facilitate the MapReduce task to read and write htable data.

Package Taglib.customer;import java.io.IOException;  Import org.apache.hadoop.conf.Configuration;  Import org.apache.hadoop.hbase.HBaseConfiguration;  Import Org.apache.hadoop.hbase.client.Put;  Import Org.apache.hadoop.hbase.client.Result;  Import Org.apache.hadoop.hbase.client.Scan;  Import org.apache.hadoop.hbase.io.ImmutableBytesWritable;  Import Org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;  Import Org.apache.hadoop.hbase.mapreduce.TableMapper;  Import Org.apache.hadoop.hbase.mapreduce.TableReducer;  Import org.apache.hadoop.hbase.util.Bytes;  Import org.apache.hadoop.io.IntWritable;  Import Org.apache.hadoop.io.Text; Import Org.apache.hadoop.mapreduce.job;public class Mrhbase {public static void main (string[] args) throws IOException, C Lassnotfoundexception, Interruptedexception {//TODO auto-generated method Stubconfiguration conf =  Hbaseconfiguration.create ();        Conf.set ("Hbase.zookeeper.quorum", "192.168.58.101");       Job Job = new Job (conf, "examplesummary");   Job.setjarbyclass (Mrhbase.class);          Class that contains mapper and reducer scan scan = new scan ();        Scan.setcaching (500);  1 is the default in Scan, which would be a bad for MapReduce jobs scan.setcacheblocks (FALSE);          Don ' t set to true for MR jobs//Set other scan attrs//scan.addcolumn (family, qualifier);               Tablemapreduceutil.inittablemapperjob ("blog",//Input table scan,                  Scan instance to control CF and attribute selection Mymapper.class,//Mapper class                  Text.class,//Mapper output key Intwritable.class,//Mapper output value          Job); Tablemapreduceutil.inittablereducerjob ("blog2",//Output table MYTABLEREDUCER.C          Lass,//reducer class job);   Job.setnumreducetasks (1); At least one, adjust as RequiRed Boolean B = Job.waitforcompletion (true);          if (!b) {throw new IOException ("Error with job!"); }}public Static class Mymapper extends Tablemapper<text, intwritable> {private final intwritable one =          New Intwritable (1);            Private text text = new text ();              public void Map (immutablebyteswritable row, Result value, Context context) throws IOException, Interruptedexception {              String IP = bytes.tostring (Row.get ());              String url = new String (Value.getvalue (Bytes.tobytes ("article"), Bytes.tobytes ("title"));              Text.set (ip+ "&" +url);          Context.write (text, one);          }}public Static class Mytablereducer extends Tablereducer<text, intwritable, immutablebyteswritable> { public void reduce (Text key, iterable<intwritable> values, context context) throws IOException, interruptedexcept              ion {int sum = 0; for (intwritable VAl:values) {sum + = Val.get ();              Put put = new put (key.getbytes ());                Put.add (Bytes.tobytes ("article"), Bytes.tobytes ("title"), Bytes.tobytes (string.valueof (sum)));          Context.write (null, put); }      }  }

Hbase->mapreduce->hbase