MapReduce编程模板

 

 

 

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.io.IntWritable;
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.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.mapreduce.lib.partition.HashPartitioner;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class ModuleMapReduce extends Configured implements Tool {

	static class ModuleMapper extends
			Mapper<LongWritable, Text, Text, IntWritable> {
		@Override
		protected void setup(
				Mapper<LongWritable, Text, Text, IntWritable>.Context context)
				throws IOException, InterruptedException {
			// TODO Auto-generated method stub
			super.setup(context);
		}

		@Override
		protected void map(LongWritable key, Text value,
				Mapper<LongWritable, Text, Text, IntWritable>.Context context)
				throws IOException, InterruptedException {
			// TODO Auto-generated method stub
			super.map(key, value, context);
		}

		@Override
		protected void cleanup(
				Mapper<LongWritable, Text, Text, IntWritable>.Context context)
				throws IOException, InterruptedException {
			// TODO Auto-generated method stub
			super.cleanup(context);
		}

		@Override
		public void run(
				Mapper<LongWritable, Text, Text, IntWritable>.Context context)
				throws IOException, InterruptedException {
			// TODO Auto-generated method stub
			super.run(context);
		}

	}

	static class ModuleReducer extends
			Reducer<Text, IntWritable, Text, IntWritable> {
		@Override
		protected void setup(
				Reducer<Text, IntWritable, Text, IntWritable>.Context context)
				throws IOException, InterruptedException {
			// TODO Auto-generated method stub
			super.setup(context);
		}

		@Override
		protected void reduce(Text key, Iterable<IntWritable> values,
				Reducer<Text, IntWritable, Text, IntWritable>.Context context)
				throws IOException, InterruptedException {
			// TODO Auto-generated method stub
			super.reduce(key, values, context);
		}

		@Override
		protected void cleanup(
				Reducer<Text, IntWritable, Text, IntWritable>.Context context)
				throws IOException, InterruptedException {
			// TODO Auto-generated method stub
			super.cleanup(context);
		}

		@Override
		public void run(
				Reducer<Text, IntWritable, Text, IntWritable>.Context context)
				throws IOException, InterruptedException {
			// TODO Auto-generated method stub
			super.run(context);
		}

	}

	@Override
	public int run(String[] args) throws Exception {
		if (checkArgs(args) != 0)
			return checkArgs(args);

		Job job = getJob();
		//set input/output path
		FileInputFormat.addInputPath(job, new Path(args[0]));
		FileOutputFormat.setOutputPath(job, new Path(args[1]));
		// set run jar class when package need
		job.setJarByClass(ModuleMapper.class);
		//set map info
		job.setMapperClass(ModuleMapper.class);
		job.setInputFormatClass(TextInputFormat.class);
		job.setMapOutputKeyClass(Text.class);
		job.setMapOutputValueClass(LongWritable.class);
		//set partition
		job.setPartitionerClass(HashPartitioner.class);
		job.setNumReduceTasks(1);
		//set reduce info
		job.setReducerClass(ModuleReducer.class);
		job.setOutputFormatClass(TextOutputFormat.class);
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(IntWritable.class);

		return job.waitForCompletion(true) ? 0 : 1;
	}

	private Configuration getConfiguration() {
		Configuration conf = new Configuration();
		return conf;
	}

	private Job getJob() throws IOException {
		Configuration conf = getConfiguration();
		Job job = new Job(conf, ModuleMapReduce.class.getSimpleName());
		return job;
	}

	private int checkArgs(String[] args) {
		if (args.length != 2) {
			System.err.println("args error");
			return 1;
		}
		return 0;
	}

	public static void main(String[] args) throws Exception {
		int exitCode = ToolRunner.run(new ModuleMapReduce(), args);
		System.exit(exitCode);
	}
}