编写MaxTemperature测试用例

(1) 源代码

package cn.edu.xjtu.temperature;

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;

public class MaxTemperature {
	
	static class MaxTemperatureMapper extends 
	Mapper<LongWritable, Text, Text, IntWritable> {
		private static final int MISSING = 9999;
		
		public void map(LongWritable key, Text value, Context context)
			throws IOException, InterruptedException{
			String line = value.toString();
			String year = line.substring(15, 19);
			System.out.println(year);
			int airTemperature;
			if(line.charAt(40) == '+'){
				airTemperature = Integer.parseInt(line.substring(41,45));
			}else{
				airTemperature = Integer.parseInt(line.substring(40,45));
			}
			
			String quality = line.substring(45,46);
			if(airTemperature != MISSING && quality.matches("[01459]")){
				context.write(new Text(year), new IntWritable(airTemperature));
			}
		}
	}
	
	static class MaxTemperatureReducer extends
	Reducer<Text, IntWritable, Text, IntWritable> {
		public void reduce(Text key, Iterable<IntWritable> values, Context context) 
		throws IOException, InterruptedException {
			int maxValue = Integer.MIN_VALUE;
			for(IntWritable value : values){
				maxValue = Math.max(maxValue, value.get());
			}
			context.write(key, new IntWritable(maxValue));
		}
	}
	
	public static void main(String[] args) throws Exception {
		if(args.length != 2){
			System.err.println("Usage: MaxTemperature <input path> <output path>");
			System.exit(-1);
		}
		
		Job job = new Job();                  
		job.setJarByClass(MaxTemperature.class);
		
		FileInputFormat.addInputPath(job, new Path(args[0]));
		FileOutputFormat.setOutputPath(job, new Path(args[1]));
		
		job.setMapperClass(MaxTemperatureMapper.class);
		job.setCombinerClass(MaxTemperatureReducer.class);
		job.setReducerClass(MaxTemperatureReducer.class);
		
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(IntWritable.class);
		
		System.exit(job.waitForCompletion(true)? 0 : 1);
	}
}

2. 测试数据 record.txt，传到node14

0067011990999991950051507004...9999999N9+00001+99999999999...
0043011990999991950051512004...9999999N9+00221+99999999999...
0043011990999991950051518004...9999999N9-00111+99999999999...
0043012650999991949032412004...0500001N9+01111+99999999999...
0043012650999991949032418004...0500001N9+00781+99999999999...

3. 从eclipse中export出 maxTemperature.jar，传到node14

4. 执行

      (1) [hadoop@node14 app]$ hadoop fs -put record.txt input.txt

      (2) [hadoop@node14 app]$ hadoop jar maxTemperature.jar cn.edu.xjtu.temperature.MaxTemperature input.txt outputDir

      (3) 查看执行结果

             [hadoop@node14 app]$ hadoop fs -ls outputDir

             [hadoop@node14 app]$ hadoop fs -cat outputDir/part-r-00000

             1949    111
             1950    22