MapReduce操作Hbase --table2file

官方手册：http://hbase.apache.org/book.html#mapreduce.example

简单的操作，将hbase表中的数据写入到文件中。

RunJob 源码：

 1 import org.apache.hadoop.conf.Configuration;
 2 import org.apache.hadoop.fs.FileSystem;
 3 import org.apache.hadoop.fs.Path;
 4 import org.apache.hadoop.hbase.HBaseConfiguration;
 5 import org.apache.hadoop.hbase.client.Scan;
 6 import org.apache.hadoop.hbase.mapreduce.TableInputFormat;
 7 import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
 8 import org.apache.hadoop.io.Text;
 9 import org.apache.hadoop.mapreduce.Job;
10 import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
11 import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
12 import org.apache.hadoop.util.Tool;
13 import org.apache.hadoop.util.ToolRunner;
14
15 /**
16  * Created by Edward on 2016/6/29.
17  */
18 public class RunJob implements Tool {
19
20     private Configuration conf = null;
21
22     @Override
23     public int run(String[] strings) throws Exception {
24
25         Configuration conf = this.getConf();
26
27         FileSystem fs = FileSystem.get(conf);
28
29         Job job = Job.getInstance(conf,"etl");
30         job.setJarByClass(RunJob.class);
31
32         job.setInputFormatClass(TableInputFormat.class);
33         job.setOutputFormatClass(TextOutputFormat.class);
34         job.setOutputKeyClass(TextOutputFormat.class);
35
36         Scan scan = new Scan();
37         scan.setCaching(1024);
38         scan.setCacheBlocks(false);
39
40         TableMapReduceUtil.initTableMapperJob("test1",
41                 scan,
42                 MyMapper.class,
43                 Text.class,
44                 Text.class,
45                 job);
46
47         Path path = new Path("/hbase_out");
48         if(fs.exists(path))
49         {
50             fs.delete(path,true);
51         }
52
53         FileOutputFormat.setOutputPath(job, new Path("/hbase_out"));
54
55         boolean b = job.waitForCompletion(true);
56         if(b)
57         {
58             System.out.println("执行成功");
59         }
60         return 0;
61     }
62
63     @Override
64     public void setConf(Configuration configuration) {
65
66         System.setProperty("HADOOP_USER_NAME","root");
67         configuration.set("hbase.zookeeper.quorum","node1,node2,node3");
68         configuration.set("mapred.jar","D:\\etl.jar");
69
70         this.conf = HBaseConfiguration.create(configuration);
71     }
72
73     @Override
74     public Configuration getConf() {
75         return this.conf;
76     }
77
78     public static void main(String[] args)
79     {
80         try {
81             ToolRunner.run(new Configuration(), new RunJob(), args);
82         } catch (Exception e) {
83             e.printStackTrace();
84         }
85     }
86 }

MyMapper代码：

 1 import org.apache.hadoop.hbase.client.Result;
 2 import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
 3 import org.apache.hadoop.hbase.mapreduce.TableMapper;
 4 import org.apache.hadoop.io.Text;
 5
 6 import java.io.IOException;
 7
 8 /**
 9  * Created by Edward on 2016/6/29.
10  */
11 public class MyMapper extends TableMapper<Text, Text>{
12     @Override
13     protected void map(ImmutableBytesWritable key, Result value, Context context) throws IOException, InterruptedException {
14
15         String val = new String(value.getValue("info".getBytes(),"name".getBytes()));
16         String row = new String(value.getRow());
17         context.write(new Text(row), new Text(val));
18     }
19 }

MyReducer代码：

 1 import org.apache.hadoop.io.Text;
 2 import org.apache.hadoop.mapreduce.Reducer;
 3
 4 import java.io.IOException;
 5
 6 /**
 7  * Created by Edward on 2016/6/29.
 8  */
 9 public class MyReducer extends Reducer<Text,Text,Text,Text>{
10
11     @Override
12     protected void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
13         for(Text t:values) {
14             context.write(key, t);
15         }
16     }
17 }