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package hello_hadoop; import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.DoubleWritable; 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.Partitioner; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; public class AutoParitionner { public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException { if(args.length!=2) { System.err.println("Usage: hadoop jar xxx.jar <input path> <output path>"); System.exit(1); } Configuration conf = new Configuration(); Job job = Job.getInstance(conf, "avg of grades"); job.setJarByClass(AutoParitionner.class); job.setMapperClass(PartitionInputClass.class); job.setReducerClass(PartitionOutputClass.class); job.setMapOutputKeyClass(Text.class); job.setMapOutputValueClass(DoubleWritable.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(DoubleWritable.class); //声明自定义分区的类,下面有类的声明 job.setPartitionerClass(MyPartitioner.class); job.setNumReduceTasks(2); FileInputFormat.addInputPath(job, new Path(args[0])); FileOutputFormat.setOutputPath(job, new Path(args[1])); System.exit(job.waitForCompletion(true)?0:1); } } class PartitionInputClass extends Mapper<LongWritable, Text, Text, DoubleWritable>{ @Override protected void map(LongWritable key, Text value, Mapper<LongWritable, Text, Text, DoubleWritable>.Context context) throws IOException, InterruptedException { String line = value.toString(); if(line.length()>0){ String[] array = line.split("\t"); if(array.length==2){ String name=array[0]; int grade = Integer.parseInt(array[1]); context.write(new Text(name), new DoubleWritable(grade)); } } } } class PartitionOutputClass extends Reducer<Text, DoubleWritable, Text, DoubleWritable>{ @Override protected void reduce(Text text, Iterable<DoubleWritable> iterable, Reducer<Text, DoubleWritable, Text, DoubleWritable>.Context context) throws IOException, InterruptedException { int sum = 0; int cnt= 0 ; for(DoubleWritable iw : iterable) { sum+=iw.get(); cnt++; } context.write(text, new DoubleWritable(sum/cnt)); } } //自定义分区的类 //Partitioner<Text , DoubleWritable > Text,DoubleWirtable分别为map结果的key,value class MyPartitioner extends Partitioner<Text , DoubleWritable >{ @Override public int getPartition(Text text, DoubleWritable value, int numofreuceTask) { String name = text.toString(); if(name.equals("wd")||name.equals("wzf")||name.equals("xzh")||name.equals("zz")) { return 0; }else return 1; } }
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