hbase wordcount 学习

 学习hbase 这么久了，下面做一个简单的wordcount练习

• WordCountRunner 

public class HBaseWordCountRunner{
	public static void main(String[] args) throws Exception {
		Configuration conf = new Configuration();
		conf.set("fs.defaultFS", "hdfs://localhost:8020");
		conf.set("hbase.zookeeper.quorum", "localhost");
	   
		Job  job = Job.getInstance(conf);
		
		
	   job.setJarByClass(HBaseWordCountRunner.class);
	    
	   
	   	job.setMapOutputKeyClass(Text.class);
	   	
	   	job.setMapOutputValueClass(IntWritable.class);
	   		
	   	
	   job.setMapperClass(WCMapper.class);
	   TableMapReduceUtil.initTableReducerJob(
			  "wc", 
			  WCReducer.class,
			  job);
	   
	  FileInputFormat.addInputPath(job, new Path("/test"));
	  job.waitForCompletion(true);
	
	
	
	}

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• WCMapper 跟MR的mapper 写法一样

public class WCMapper 
extends Mapper<LongWritable, Text, Text, IntWritable>{

	@Override
	protected void map(LongWritable key, Text value, Mapper<LongWritable, Text, Text, IntWritable>.Context context)
			throws IOException, InterruptedException {
		String[] words = value.toString().split(" ");
		for(String word:words) {
			context.write(new Text(word), new IntWritable(1));
		}
	}
	
}

---

•  WCReduder 与MR 的reduder写法不一样

reducer 的输出类型为 ImmutableBytesWritable

public class WCReducer extends TableReducer<Text, IntWritable,
ImmutableBytesWritable>{

	@Override
	protected void reduce(Text text, Iterable<IntWritable> iterable,
			Reducer<Text, IntWritable, ImmutableBytesWritable, Mutation>.Context context)
			throws IOException, InterruptedException {
		
		int sum=0;
		for(IntWritable it:iterable) {
			sum+=it.get();
		}
		// write into hbase
		Put put = new Put(text.toString().getBytes());
		put.add("cf".getBytes(),"ct".getBytes(),(sum+"").getBytes());
		
		context.write(null, put);
		
	}

}