MapReduce的SequenceFileInputFormat使用 

  1 package com.mengyao.hadoop.mapreduce;
  2 
  3 import java.io.IOException;
  4 import java.util.Iterator;
  5 
  6 import org.apache.hadoop.conf.Configuration;
  7 import org.apache.hadoop.conf.Configured;
  8 import org.apache.hadoop.fs.Path;
  9 import org.apache.hadoop.io.IntWritable;
 10 import org.apache.hadoop.io.NullWritable;
 11 import org.apache.hadoop.io.Text;
 12 import org.apache.hadoop.mapreduce.Job;
 13 import org.apache.hadoop.mapreduce.Mapper;
 14 import org.apache.hadoop.mapreduce.Reducer;
 15 import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
 16 import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
 17 import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
 18 import org.apache.hadoop.util.Tool;
 19 import org.apache.hadoop.util.ToolRunner;
 20 
 21 /**
 22  * 使用SequenceFileInputFormat处理HDFS上的SequenceFile类型文件，输出为普通文件
 23  *
 24  * @author mengyao
 25  *
 26  */
 27 public class SequenceFileInputFormatApp extends Configured implements Tool  {
 28 
 29     static class SequenceFileInputFormatMapper extends Mapper<IntWritable, Text, NullWritable, Text> {
 30         
 31         private NullWritable outputKey;
 32         
 33         @Override
 34         protected void setup(Context context)
 35                 throws IOException, InterruptedException {
 36             this.outputKey = NullWritable.get();
 37         }
 38         
 39         @Override
 40         protected void map(IntWritable key, Text value, Context context)
 41                 throws IOException, InterruptedException {
 42             context.write(outputKey, value);
 43         }
 44     }
 45     
 46     static class SequenceFileInputFormatReducer extends Reducer<NullWritable, Text, NullWritable, Text> {
 47         
 48         private NullWritable outputKey;
 49         
 50         @Override
 51         protected void setup(Context context)
 52                 throws IOException, InterruptedException {
 53             this.outputKey = NullWritable.get();
 54         }
 55         
 56         @Override
 57         protected void reduce(NullWritable key, Iterable<Text> value, Context context)
 58                 throws IOException, InterruptedException {
 59             Iterator<Text> iterator = value.iterator();
 60             while (iterator.hasNext()) {
 61                 context.write(outputKey, iterator.next());
 62             }
 63         }
 64     }
 65 
 66     @Override
 67     public int run(String[] args) throws Exception {
 68         Job job = Job.getInstance(getConf(), SequenceFileInputFormatApp.class.getSimpleName());
 69         job.setJarByClass(SequenceFileInputFormatApp.class);
 70         
 71         job.setInputFormatClass(SequenceFileInputFormat.class);
 72         FileInputFormat.addInputPath(job, new Path(args[0]));
 73         FileOutputFormat.setOutputPath(job, new Path(args[1]));
 74         
 75         job.setMapperClass(SequenceFileInputFormatMapper.class);
 76         job.setMapOutputKeyClass(NullWritable.class);
 77         job.setMapOutputValueClass(Text.class);
 78         
 79         job.setReducerClass(SequenceFileInputFormatReducer.class);
 80         job.setOutputKeyClass(NullWritable.class);
 81         job.setOutputValueClass(Text.class);
 82         
 83         return job.waitForCompletion(true)?0:1;
 84     }
 85     
 86     public static int createJob(String[] args) {
 87         Configuration conf = new Configuration();
 88         conf.set("dfs.datanode.socket.write.timeout", "7200000");
 89         conf.set("mapreduce.input.fileinputformat.split.minsize", "268435456");
 90         conf.set("mapreduce.input.fileinputformat.split.maxsize", "536870912");
 91         conf.set("mapreduce.job.jvm.numtasks", "-1");        
 92         conf.set("mapreduce.map.speculative", "false");        
 93         conf.set("mapreduce.reduce.speculative", "false");    
 94         conf.set("mapreduce.map.maxattempts", "4");            
 95         conf.set("mapreduce.reduce.maxattempts", "4");        
 96         conf.set("mapreduce.map.skip.maxrecords", "0");
 97         int status = 0;
 98         
 99         try {
100             status = ToolRunner.run(conf, new SequenceFileInputFormatApp(), args);
101         } catch (Exception e) {
102             e.printStackTrace();
103         }
104         
105         return status;
106     }
107     
108     public static void main(String[] args) {
109         args = new String[]{"/mapreduces/seqfile/book1.txt", "/mapreduces/sequencefileinputformat"};
110         if (args.length!=2) {
111             System.out.println("Usage: "+SequenceFileInputFormatApp.class.getName()+" Input paramters <INPUT_PATH> <OUTPUT_PATH>");
112         } else {
113             int status = createJob(args);
114             System.exit(status);
115         }
116     }
117 }

 

posted @ 2013-02-06 15:05  孟尧  阅读(765)  评论(1)    收藏  举报