hbase -MR将输出输出到hbase里面示例

1、主要是设置Reduce端输出的value类型

直接上代码吧：注释就免了吧，大家应该很熟悉了。

package hbase;

import java.io.IOException;
import java.util.StringTokenizer;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.mapreduce.TableOutputFormat;
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.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;

public class WordCountHBase {

	/**
	 * @param args
	 * @throws IOException
	 * @throws ClassNotFoundException
	 * @throws InterruptedException
	 */
	public static void main(String[] args) throws IOException,
			InterruptedException, ClassNotFoundException {
		// TODO Auto-generated method stub
		String tablename = "wordcount";
		Configuration conf = new Configuration();
		conf.set(TableOutputFormat.OUTPUT_TABLE, tablename);
		createHBaseTable(tablename);

		Job job = new Job(conf, "WordCount table");
		job.setJarByClass(WordCountHBase.class);
		job.setNumReduceTasks(3);
		job.setMapperClass(Map.class);
		job.setReducerClass(Reduce.class);
		job.setMapOutputKeyClass(Text.class);
		job.setMapOutputValueClass(IntWritable.class);
		job.setInputFormatClass(TextInputFormat.class);
		job.setOutputFormatClass(TableOutputFormat.class);
		// ?????????¼
		FileInputFormat.addInputPath(job, new Path(
				"hdfs://hadoop:9000/input"));
		System.exit(job.waitForCompletion(true) ? 0 : 1);
	}

	public static class Map extends
			Mapper<LongWritable, Text, Text, IntWritable> {
		private final static IntWritable one = new IntWritable(1);
		private Text text = new Text();

		@Override
		public void map(LongWritable key, Text value, Context context)
				throws IOException, InterruptedException {
			String s = value.toString();
			StringTokenizer st = new StringTokenizer(s);
			while (st.hasMoreTokens()) {
				text.set(st.nextToken());
				context.write(text, one);
			}
		}
	}

	public static class Reduce extends
			TableReducer<Text, IntWritable, NullWritable> {

		@Override
		public void reduce(Text key, Iterable<IntWritable> values,
				Context context) throws IOException, InterruptedException {
			int sum = 0;
			for (IntWritable i : values) {
				sum += i.get();
			}
			Put put = new Put(Bytes.toBytes(key.toString()));
			// row,columnFamily:column,value = word,content:count,sum
			put.add(Bytes.toBytes("content"), Bytes.toBytes("count"),
					Bytes.toBytes(String.valueOf(sum)));
			context.write(NullWritable.get(), put);
		}
	}

	/**
	 * create a table
	 *
	 * @param tablename
	 * @throws IOException
	 */
	public static void createHBaseTable(String tablename) throws IOException {
		HTableDescriptor htd = new HTableDescriptor(tablename);
		HColumnDescriptor col = new HColumnDescriptor("content");
		htd.addFamily(col);
		Configuration cfg = HBaseConfiguration.create();
		HBaseAdmin admin = new HBaseAdmin(cfg);
		if (admin.tableExists(tablename)) {
			System.out.println("table exists,trying recreate table!");
			admin.disableTable(tablename);
			admin.deleteTable(tablename);
			admin.createTable(htd);
		} else {
			System.out.println("create new table:" + tablename);
			admin.createTable(htd);
		}
	}
}

2、hbase shell

>list

>scan ‘wordcount‘

>............................

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