Mapreduce构建hbase二级索引

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

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.MultiTableOutputFormat;
import org.apache.hadoop.hbase.mapreduce.TableInputFormat;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.mapreduce.TableMapper;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.util.GenericOptionsParser;

public class IndexBuilder {

private class MyMapper extends TableMapper<ImmutableBytesWritable, Put> {
private Map<byte[], ImmutableBytesWritable> indexes = new HashMap<byte[], ImmutableBytesWritable>();
private String columnFamily;

@Override
protected void map(ImmutableBytesWritable key, Result value,
Context context) throws IOException, InterruptedException {

Set<byte[]> keys = indexes.keySet();
for (byte[] k : keys) {

ImmutableBytesWritable indexTableName = indexes.get(k);
byte[] val = value.getValue(Bytes.toBytes(columnFamily), k);
Put put = new Put(val);// 索引表的rowkey为原始表的值
put.add(Bytes.toBytes("f1"), Bytes.toBytes("id"), key.get());// 索引表的内容为原始表的rowkey
context.write(indexTableName, put);

}

}

@Override
protected void setup(Context context) throws IOException,
InterruptedException {
Configuration conf = context.getConfiguration();
String tableName = conf.get("tableName");
columnFamily = conf.get("columnFamily");
String[] qualifiers = conf.getStrings("qualifiers");
// indexes的key为列名，value为索引表名
for (String q : qualifiers) {
indexes.put(
Bytes.toBytes(q),
new ImmutableBytesWritable(Bytes.toBytes(tableName
+ "-" + q)));

}

}

}

public static void main(String[] args) throws IOException,
ClassNotFoundException, InterruptedException {
Configuration conf = HBaseConfiguration.create();

String[] otherargs = new GenericOptionsParser(conf, args)
.getRemainingArgs();// 去除掉没有用的命令行参数
// 输入参数：表名，列族名，列名
if (otherargs.length < 3) {
System.exit(-1);
}
String tableName = otherargs[0];
String columnFamily = otherargs[1];

conf.set("tableName", tableName);
conf.set("columnFamily", columnFamily);

String[] qualifiers = new String[otherargs.length - 2];
for (int i = 0; i < qualifiers.length; i++) {

qualifiers[i] = otherargs[i + 2];
}
conf.setStrings("qualifiers", qualifiers);
Job job = new Job(conf, tableName);
job.setJarByClass(IndexBuilder.class);
job.setMapperClass(MyMapper.class);
job.setNumReduceTasks(0);
job.setInputFormatClass(TableInputFormat.class);
// 可以输出多张表
job.setOutputFormatClass(MultiTableOutputFormat.class);
Scan scan = new Scan();
scan.setCaching(1000);
TableMapReduceUtil.initTableMapperJob(tableName, scan, MyMapper.class,
ImmutableBytesWritable.class, Put.class, job);
job.waitForCompletion(true);

}

}