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創(chuàng)新互聯(lián)-專業(yè)網(wǎng)站定制、快速模板網(wǎng)站建設(shè)、高性價比蔡甸網(wǎng)站開發(fā)、企業(yè)建站全套包干低至880元,成熟完善的模板庫,直接使用。一站式蔡甸網(wǎng)站制作公司更省心,省錢,快速模板網(wǎng)站建設(shè)找我們,業(yè)務(wù)覆蓋蔡甸地區(qū)。費用合理售后完善,10多年實體公司更值得信賴。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); //聲明自定義分區(qū)的類,下面有類的聲明 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)); } } //自定義分區(qū)的類 //Partitioner<Text , DoubleWritable > Text,DoubleWirtable分別為map結(jié)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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