MapReduce java 应用

 

java 代码

package cn.AAA.demo;import java.io.IOException;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.output.FileOutputFormat;/** * * @author DELL * */public class MaxTemperature {// MAPstatic class MaxTempertureMapper extendsMapper<LongWritable, Text, Text, IntWritable> {@Overrideprotected void map(LongWritable key, Text value,Context context)throws IOException, InterruptedException {String line = value.toString();for(int i=0;i<line.length();i++){char c = line.charAt(i);context.write(new Text(c+""),new IntWritable(1));}}}// REDUCEstatic class MaxTempertureReduce extendsReducer<Text, IntWritable, Text, IntWritable> {@Overrideprotected void reduce(Text text, Iterable<IntWritable> values,Context context) throws IOException, InterruptedException {int count = 0;for (IntWritable value:values){count = count+Integer.parseInt(value+"");}context.write(text,new IntWritable(count));}} public static void main(String [] args)throws Exception { Job job = new Job(); job.setJarByClass(MaxTemperature.class); FileInputFormat.addInputPath(job, new Path("/workspace/rsync/map/in2.txt")); FileOutputFormat.setOutputPath(job, new Path("/workspace/rsync/map/out2")); job.setMapperClass(MaxTempertureMapper.class); job.setReducerClass(MaxTempertureReduce.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); System.exit(job.waitForCompletion(true)?0:1); }}