| 2 | | |
| 3 | | {{{ |
| 4 | | #!java |
| 5 | | package org.nchc.hadoop; |
| 6 | | import java.io.IOException; |
| 7 | | |
| 8 | | import org.apache.hadoop.io.LongWritable; |
| 9 | | import org.apache.hadoop.io.Text; |
| 10 | | import org.apache.hadoop.mapreduce.Mapper; |
| 11 | | |
| 12 | | public class HelloMapperV2 extends Mapper<LongWritable, Text, Text, Text> { |
| 13 | | |
| 14 | | public void map(LongWritable key, Text value, Context context) |
| 15 | | throws IOException, InterruptedException { |
| 16 | | context.write(new Text(key.toString()), value); |
| 17 | | } |
| 18 | | |
| 19 | | } |
| 20 | | |
| 21 | | }}} |
| 22 | | |
| 23 | | = HelloReducerV2.java = |
| 24 | | |
| 25 | | {{{ |
| 26 | | #!java |
| 27 | | package org.nchc.hadoop; |
| 28 | | import java.io.IOException; |
| 29 | | |
| 30 | | import org.apache.hadoop.io.Text; |
| 31 | | import org.apache.hadoop.mapreduce.Reducer; |
| 32 | | |
| 33 | | public class HelloReducerV2 extends Reducer<Text, Text, Text, Text> { |
| 34 | | public void reduce(Text key, Iterable<Text> values, Context context) |
| 35 | | throws IOException, InterruptedException { |
| 36 | | |
| 37 | | String str = new String(""); |
| 38 | | Text final_key = new Text(); |
| 39 | | Text final_value = new Text(); |
| 40 | | // 將key值相同的values，透過 && 符號分隔之 |
| 41 | | for (Text tmp : values) { |
| 42 | | str += tmp.toString() + " &&"; |
| 43 | | } |
| 44 | | |
| 45 | | final_key.set(key); |
| 46 | | final_value.set(str); |
| 47 | | |
| 48 | | context.write(final_key, final_value); |
| 49 | | } |
| 50 | | } |
| 51 | | |
| 52 | | }}} |
