org.apache.hadoop.hbase.mapreduce

TableMapper  TableReducer

一个region对应一个map

import java.io.IOException;import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Mutation;
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.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Reducer;public class HbaseMR {public class MyMapper extends TableMapper<Text, Text> {@Overrideprotected void map(ImmutableBytesWritable key, Result value,Context context) throws IOException, InterruptedException {// key代表rowkeyText k = new Text(Bytes.toString(key.get()));Text v = new Text(Bytes.toString(value.getValue("basicinfo".getBytes(), "age".getBytes())));context.write(v, k);}}public class MyReducer extends TableReducer<Text, Text, Text> {@Overrideprotected void reduce(Text key, Iterable<Text> values, Context context)throws IOException, InterruptedException {Put put = new Put(Bytes.toBytes(key.toString()));for (Text value : values) {put.add(Bytes.toBytes("f1"), Bytes.toBytes(value.toString()),Bytes.toBytes(value.toString()));}context.write(null, put);}}public static void main(String[] args) {Configuration conf=    HBaseConfiguration.create();try {Job job=new Job(conf, "mapreduce on hbase");job.setJarByClass(HbaseMR.class);Scan scan=new Scan();scan.setCaching(1000);//TableMapReduceUtil.initTableMapperJob("students", scan, MyMapper.class, Text.class, Text.class, job);TableMapReduceUtil.initTableReducerJob("student-age",  MyReducer.class,  job);job.waitForCompletion(true);} catch (Exception e) {e.printStackTrace();}}}

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