1，在Hadoop中，reduce支持多个输出,输出的文件名也是可控的，就是继承MultipleTextOutputFormat类，重写generateFileNameForKey方法
[java]
public class LzoHandleLogMr extends Configured implements Tool { static class LzoHandleLogMapper extends MapReduceBase implements Mapper<LongWritable, Text, Text, Text> { public void map(LongWritable key, Text value, OutputCollector<Text, Text> output, Reporter reporter) throws IOException { try { String[] sp = value.toString().split(","); output.collect(new Text(sp[0]), value); }catch (Exception e) { e.printStackTrace(); } } } static class LzoHandleLogReducer extends MapReduceBase implements Reducer<Text, Text, Text, NullWritable> { @Override public void reduce(Text key, Iterator<Text> values, OutputCollector<Text, NullWritable> output, Reporter reporter) throws IOException { while (values.hasNext()) { output.collect(values.next(), NullWritable.get()); } } } public static class LogNameMultipleTextOutputFormat extends MultipleTextOutputFormat<Text, NullWritable> { @Override protected String generateFileNameForKeyValue(Text key, NullWritable value, String name) { String sp[] = key.toString().split(","); String filename = sp[0]; if(sp[0].contains(".")) filename="000000000000"; return filename; } } @Override public int run(String[] args) throws Exception { JobConf jobconf = new JobConf(LzoHandleLogMr.class); jobconf.setMapperClass(LzoHandleLogMapper.class); jobconf.setReducerClass(LzoHandleLogReducer.class); jobconf.setOutputFormat(LogNameMultipleTextOutputFormat.class); jobconf.setOutputKeyClass(Text.class); jobconf.setNumReduceTasks(12); FileInputFormat.setInputPaths(jobconf,new Path(args[0])); FileOutputFormat.setOutputPath(jobconf,new Path(args[1])); FileOutputFormat.setCompressOutput(jobconf, true); FileOutputFormat.setOutputCompressorClass(jobconf, LzopCodec.class); JobClient.runJob(jobconf); return 0; } }