Hadoop 查找最大数
package com.lch.find;import java.io.IOException;import java.util.Iterator;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.FloatWritable;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;import org.apache.hadoop.util.GenericOptionsParser;public class SearchMaxValue {public static class SearchMaxValueMapper extends Mapper<LongWritable, Text, IntWritable, FloatWritable>{private final static IntWritable one = new IntWritable(1);@Overrideprotected void map(LongWritable key, Text value, Context context)throws IOException, InterruptedException {String str = value.toString().trim();float flo = Float.parseFloat(str);context.write(one, new FloatWritable(flo));}}public static class SearchMaxValueReducer extends Reducer<IntWritable, FloatWritable, Text, FloatWritable>{@SuppressWarnings("rawtypes")public void reduce(IntWritable key, Iterable<FloatWritable> values, Context context) throws IOException, InterruptedException{Iterator it = values.iterator();float maxFloat = 0, tmp;if(it.hasNext()){maxFloat = ((FloatWritable) it.next()).get();}else{context.write(new Text("Max Value : "), null);return;}while(it.hasNext()){tmp = ((FloatWritable) it.next()).get();if(tmp > maxFloat){maxFloat = tmp;}}context.write(new Text("Max value is :"), new FloatWritable(maxFloat));}}public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {Configuration conf = new Configuration();String[] paths = { "hdfs://192.168.1.136:9000/tmp/test.txt", "hdfs://192.168.1.136:9000/tmp/outputs" };String[] otherArgs = new GenericOptionsParser(conf, paths).getRemainingArgs();Job job = new Job(conf, "SearchValue");job.setJarByClass(SearchMaxValue.class);job.setMapperClass(SearchMaxValueMapper.class);job.setReducerClass(SearchMaxValueReducer.class);job.setMapOutputKeyClass(IntWritable.class);job.setMapOutputValueClass(FloatWritable.class);job.setOutputKeyClass(Text.class);job.setOutputValueClass(FloatWritable.class);FileInputFormat.addInputPath(job, new Path(otherArgs));FileOutputFormat.setOutputPath(job, new Path(otherArgs));System.exit(job.waitForCompletion(true) ? 0 : 1);}}代码比较简单 不多解释
附上数据信息
12.5
85.0
236
239
23
2
0
1
9
236
232.0
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