hbase 从hbase上读取数据写入到hdfs

Mapper

 package cn.hbase.mapreduce.hb2hdfs;

 import java.io.IOException;
 import org.apache.hadoop.hbase.client.Result;
 import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
 import org.apache.hadoop.hbase.mapreduce.TableMapper;

 /**
  *
  * @author Tele
  *
  * 输出key 行键 输出out 读出的一行数据
  */

 public class ReadFruitFromHbMapper extends TableMapper<ImmutableBytesWritable, Result> {

     @Override
     protected void map(ImmutableBytesWritable key, Result value, Context context)
             throws IOException, InterruptedException {
         context.write(key, value);
     }
 }

Reducer

 package cn.hbase.mapreduce.hb2hdfs;

 import java.io.IOException;

 import org.apache.hadoop.hbase.Cell;
 import org.apache.hadoop.hbase.CellScanner;
 import org.apache.hadoop.hbase.CellUtil;
 import org.apache.hadoop.hbase.client.Result;
 import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.io.NullWritable;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.mapreduce.Reducer;

 /**
  *
  * @author Tele
  *
  */

 public class WriteFruit2HdfsReducer extends Reducer<ImmutableBytesWritable, Result, NullWritable, Text> {
     @Override
     protected void reduce(ImmutableBytesWritable key, Iterable<Result> values, Context context)
             throws IOException, InterruptedException {
         for (Result result : values) {
             CellScanner scanner = result.cellScanner();
             while (scanner.advance()) {
                 Cell cell = scanner.current();
                 Text text = new Text();
                 // 封装数据
                 String row = Bytes.toString(CellUtil.cloneRow(cell)) + "\t";
                 String cf = Bytes.toString(CellUtil.cloneFamily(cell)) + "\t";
                 String cn = Bytes.toString(CellUtil.cloneQualifier(cell)) + "\t";
                 String value = Bytes.toString(CellUtil.cloneValue(cell)) + "\t";

                 StringBuffer buffer = new StringBuffer();
                 buffer.append(row).append(cf).append(cn).append(value);
                 text.set(buffer.toString());

                 // 写出
                 context.write(NullWritable.get(), text);
             }

         }

     }
 }

Runner

 package cn.hbase.mapreduce.hb2hdfs;

 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.conf.Configured;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hbase.HBaseConfiguration;
 import org.apache.hadoop.hbase.client.Result;
 import org.apache.hadoop.hbase.client.Scan;
 import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
 import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
 import org.apache.hadoop.io.NullWritable;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.mapreduce.Job;
 import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
 import org.apache.hadoop.util.Tool;
 import org.apache.hadoop.util.ToolRunner;

 /**
  *
  * @author Tele
  *
  */

 public class FruitRunner extends Configured implements Tool {

     public int run(String[] args) throws Exception {

         System.setProperty("HADOOP_USER_NAME", "tele");
         // 实例化job
         Job job = Job.getInstance(this.getConf());

         // 设置jar
         job.setJarByClass(FruitRunner.class);

         // 设置缓存行键
         Scan scan = new Scan();
         scan.setCaching(300);
 　　　　　　
         // 组装mapper
         TableMapReduceUtil.initTableMapperJob("fruit", scan, ReadFruitFromHbMapper.class, ImmutableBytesWritable.class,
                 Result.class, job);
         // 组装reuder
         job.setReducerClass(WriteFruit2HdfsReducer.class);
         job.setOutputKeyClass(NullWritable.class);
         job.setOutputValueClass(Text.class);

         FileOutputFormat.setOutputPath(job, new Path("/outputfruit"));

         // reduce个数
         job.setNumReduceTasks(1);

         // 提交
         return job.waitForCompletion(true) ? 0 : 1;
     }

     public static void main(String[] args) throws Exception {
         Configuration conf = HBaseConfiguration.create();
         ToolRunner.run(conf, new FruitRunner(), args);
     }

 }