Hadoop示例程序之单词统计MapReduce
2012-12-06 15:05
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在eclipse下新建一个map/reduce Project
1,新建文件MyMap.java
2,新建文件MyReduce.java:2,新建文件MyReduce.java:
3,新建一个文件MyDriver.java3,新建一个文件MyDriver.java
1,新建文件MyMap.java
import java.io.IOException; import java.util.StringTokenizer; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Mapper; public class MyMap extends Mapper<Object, Text, Text, IntWritable> { private final static IntWritable one = new IntWritable(1); private Text word; public void map(Object key, Text value, Context context) throws IOException, InterruptedException { String line = value.toString(); StringTokenizer tokenizer = new StringTokenizer(line); while (tokenizer.hasMoreTokens()) { word = new Text(); word.set(tokenizer.nextToken()); context.write(word, one); } } }
2,新建文件MyReduce.java:2,新建文件MyReduce.java:
import java.io.IOException; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Reducer; public class MyReduce extends Reducer<Text, IntWritable, Text, IntWritable> { public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { int sum = 0; for (IntWritable val : values) { sum += val.get(); } context.write(key, new IntWritable(sum)); } }
3,新建一个文件MyDriver.java3,新建一个文件MyDriver.java
import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Job; 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; public class MyDriver { public static void main(String[] args) throws Exception,InterruptedException { Configuration conf=new Configuration(); Job job=new Job(conf,"Hello Hadoop World"); job.setJarByClass(MyDriver.class); job.setMapOutputKeyClass(Text.class); job.setMapOutputValueClass(IntWritable.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); job.setMapperClass(MyMap.class); job.setCombinerClass(MyReduce.class); job.setReducerClass(MyReduce.class); job.setInputFormatClass(TextInputFormat.class); job.setOutputFormatClass(TextOutputFormat.class); FileInputFormat.setInputPaths(job, new Path("./input/555.txt")); FileOutputFormat.setOutputPath(job, new Path("./input/out.txt")); job.waitForCompletion(true); } }
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