hadoop学习笔记之倒排索引

开发工具：eclipse

目标：对下面文档phone_numbers进行倒排索引：

13599999999 10086
13899999999 120
13944444444 13800138000
13722222222 13800138000
18800000000 120
13722222222 10086
18944444444 10086

代码：

 1 import java.io.IOException;
 2 import org.apache.hadoop.conf.Configured;
 3 import org.apache.hadoop.conf.Configuration;
 4 import org.apache.hadoop.fs.Path;
 5 import org.apache.hadoop.util.Tool;
 6 import org.apache.hadoop.util.ToolRunner;
 7 import org.apache.hadoop.io.*;
 8 import org.apache.hadoop.mapreduce.*;
 9 import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
10 import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
11 import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
12 
13 public class Test_1 extends Configured implements Tool 
14 {
15     enum Counter
16     {
17         LINESKIP, // error lines
18     }
19     
20     public static class Map extends Mapper<LongWritable, Text, Text, Text>
21     {
22         public void map(LongWritable key, Text value, Context context)throws IOException, InterruptedException
23         {
24             String line = value.toString(); // read original data
25             
26             try
27             {
28                 // process data
29                 String[] lineSplit = line.split(" ");
30                 String anum = lineSplit[0];
31                 String bnum = lineSplit[1];
32                 
33                 context.write(new Text(bnum), new Text(anum)); // map output
34             }
35             catch(java.lang.ArrayIndexOutOfBoundsException e)
36             {
37                 context.getCounter(Counter.LINESKIP).increment(1);
38                 return;
39             }
40             
41         }
42     }
43     public static class Reduce extends Reducer<Text, Text, Text, Text>
44     {
45         public void reduce(Text key, Iterable<Text>values, Context context)throws IOException, InterruptedException
46         {
47             String valueString;
48             String out = "";
49             
50             for (Text value : values)
51             {
52                 valueString = value.toString();
53                 out += valueString + "|";
54             }
55             
56             context.write(key, new Text(out));    // reduce output
57         }
58     }
59     public int run(String[] args)throws Exception
60     {
61         Configuration conf = getConf();
62         
63         Job job = new Job(conf, "Test_1");  // task name
64         job.setJarByClass(Test_1.class);    // specified task
65         
66         FileInputFormat.addInputPath(job, new Path(args[0]));  // input path
67         FileOutputFormat.setOutputPath(job, new Path(args[1])); // output path
68         
69         job.setMapperClass(Map.class);
70         job.setReducerClass(Reduce.class);
71         job.setOutputFormatClass(TextOutputFormat.class);
72         job.setOutputKeyClass(Text.class);
73         job.setOutputValueClass(Text.class);
74         
75         job.waitForCompletion(true);
76         
77         return job.isSuccessful() ? 0 : 1;
78     }
79     
80     public static void main(String[] args)throws Exception
81     {
82         int res = ToolRunner.run(new Configuration(), new Test_1(), args);
83         System.exit(res);
84     }
85 }

运行结果：

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原文地址：https://www.cnblogs.com/90zeng/p/hadoop_sort.html