MapReduce 多文件输出

private static class ReducerClass extends Reducer<Text, Text, Text, NullWritable> {
	private MultipleOutputs out = null;

	@Override
	protected void setup(Context context) throws IOException, InterruptedException {
		out = new MultipleOutputs(context);
	}

	@Override
	protected void cleanup(Context context) throws IOException, InterruptedException {
	    if (null != out) {
		    out.close();
	    }
	}
	
	protected void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
	    out.write(KEY, VALUE, TAG);     // TAG用于输出文件前缀
	}
}
​