* output: hbase table 

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.LongWritable;
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;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

/*
 需求：
    File中解析資料到HBase表中（import）
			Mapreduce
		 * input: hdfs files  
		   Mapper:OutputKey/OutputValue
		 * output: hbase table 
 */
public class HDFS2UserMapReduce extends Configured implements Tool {

	// Mapper Class
	// Mapper<ImmutableBytesWritable, Result, KEYOUT, VALUEOUT>
	public static class ReadHDFSMapper extends Mapper<LongWritable, Text,Text,Put> {
		private Text mapOutputKey = new Text();
		@Override
		public void map(LongWritable key, Text value, Context context)
				throws IOException, InterruptedException {
			String lineValue = value.toString();
			String values[] =lineValue.split("\t");
			Put put = new Put(Bytes.toBytes(values[0]));
			for(int i=0;i<values.length;i++)
			{
				if(i==0)
				{
					mapOutputKey.set(values[0]);
					continue;
				} 
			  	String column =values[i];
			  	String cf =column.substring(0, column.indexOf(':'));
			  	String cq =column.substring(column.indexOf(':')+1, column.indexOf('='));
			  	String val =column.substring(column.indexOf('=')+1, column.length());
			    put.add(Bytes.toBytes(cf),
			    		Bytes.toBytes(cq),
			      		Bytes.toBytes(val));
			}
			context.write(mapOutputKey, put);
		}

	}
	// Reducer Class
	public static class WriteBasicReducer extends
			TableReducer<Text, Put, ImmutableBytesWritable> {

		@Override
		protected void reduce(Text key, Iterable<Put> values, Context context)
				throws IOException, InterruptedException {
			for(Put put : values){
				context.write(null, put);
			}
		}

	}

	// Driver
	public int run(String[] args) throws Exception {
	     if (args.length < 2) {
		      usage("Wrong number of arguments: " + args.length);
		      System.exit(-1);
		 }
		
		// create job
		Job job = Job.getInstance(this.getConf(),//
				this.getClass().getSimpleName());
		
		// set run job class
		job.setJarByClass(this.getClass());
		
		job.setMapperClass(ReadHDFSMapper.class);
	    
		//input format
		job.setInputFormatClass(TextInputFormat.class);
		Path inputPath = new Path(args[1]);
		FileInputFormat.addInputPath(job, inputPath);
		
		TableMapReduceUtil.initTableReducerJob(
		  args[0],        // output table
		  WriteBasicReducer.class,    // reducer class
		  job//
		);
		job.setNumReduceTasks(0);   // at least one, adjust as required
		boolean b = job.waitForCompletion(true);
		if (!b) {
		  throw new IOException("error with job!");
		}
		return 0;
	}

	  /*
	   * @param errorMsg Error message.  Can be null.
	   */
	  private static void usage(final String errorMsg) {
	    if (errorMsg != null && errorMsg.length() > 0) {
	      System.err.println("ERROR: " + errorMsg);
	    }
	    System.err.println("Usage: User2HDFSMapReduce <tablename> <inputputdir> ");
	    System.err.println("Examples:  user hdfs://172.27.35.8:8020/user/hadoop/export/user ");
	
	  }

	public static void main(String[] args) throws Exception {
		// get configuration
		Configuration conf = HBaseConfiguration.create();
		
		// submit job
		int status = ToolRunner.run(//
			conf, //
			new HDFS2UserMapReduce(), //
			args//
		);
				
		// exit program
		System.exit(status);
	}
}