问题导读
1.如何修改reduce执行后文件名称?
2.实现自定义文件的输出,由哪个类来实现?
这样一个需求:
需要把原始的日志文件用hadoop做清洗后,按业务线输出到不同的目录下去,以供不同的部门业务线使用。
这个需求需要用到MultipleOutputFormat和MultipleOutputs来实现自定义多目录、文件的输出。
需要注意的是,在hadoop 0.21.x之前和之后的使用方式是不一样的:
hadoop 0.21 之前的API 中有 org.apache.hadoop.mapred.lib.MultipleOutputFormat 和 org.apache.hadoop.mapred.lib.MultipleOutputs,而到了 0.21 之后 的API为 org.apache.hadoop.mapreduce.lib.output.MultipleOutputs ,
新版的API 整合了上面旧API两个的功能,没有了MultipleOutputFormat。
本文将给出新旧两个版本的API code
1、旧版0.21.x之前的版本:
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.TextInputFormat;
import org.apache.hadoop.mapred.lib.MultipleTextOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
public class MultiFile extends Configured implements Tool {
public static class MapClass extends MapReduceBase implements
Mapper<LongWritable, Text, NullWritable, Text> {
@Override
public void map(LongWritable key, Text value,
OutputCollector<NullWritable, Text> output, Reporter reporter)
throws IOException {
output.collect(NullWritable.get(), value);
}
}
// MultipleTextOutputFormat 继承自MultipleOutputFormat,实现输出文件的分类
public static class PartitionByCountryMTOF extends
MultipleTextOutputFormat<NullWritable, Text> { // key is
// NullWritable,
// value is Text
protected String generateFileNameForKeyValue(NullWritable key,
Text value, String filename) {
String[] arr = value.toString().split(",", -1);
String country = arr[4].substring(1, 3); // 获取country的名称
return country + "/" + filename;
}
}
// 此处不使用reducer
/*
* public static class Reducer extends MapReduceBase implements
* org.apache.hadoop.mapred.Reducer<LongWritable, Text, NullWritable, Text>
* {
*
* @Override public void reduce(LongWritable key, Iterator<Text> values,
* OutputCollector<NullWritable, Text> output, Reporter reporter) throws
* IOException { // TODO Auto-generated method stub
*
* }
*
* }
*/
@Override
public int run(String[] args) throws Exception {
Configuration conf = getConf();
JobConf job = new JobConf(conf, MultiFile.class);
Path in = new Path(args[0]);
Path out = new Path(args[1]);
FileInputFormat.setInputPaths(job, in);
FileOutputFormat.setOutputPath(job, out);
job.setJobName("MultiFile");
job.setMapperClass(MapClass.class);
job.setInputFormat(TextInputFormat.class);
job.setOutputFormat(PartitionByCountryMTOF.class);
job.setOutputKeyClass(NullWritable.class);
job.setOutputValueClass(Text.class);
job.setNumReduceTasks(0);
JobClient.runJob(job);
return 0;
}
public static void main(String[] args) throws Exception {
int res = ToolRunner.run(new Configuration(), new MultiFile(), args);
System.exit(res);
}
} 复制代码
测试数据及结果:
hadoop fs -cat /tmp/multiTest.txt
5765303,1998,14046,1996,"AD","",,1,12,42,5,59,11,1,0.4545,0,0,1,67.3636,,,,
5785566,1998,14088,1996,"AD","",,1,9,441,6,69,3,0,1,,0.6667,,4.3333,,,,
5894770,1999,14354,1997,"AD","",,1,,82,5,51,4,0,1,,0.625,,7.5,,,,
5765303,1998,14046,1996,"CN","",,1,12,42,5,59,11,1,0.4545,0,0,1,67.3636,,,,
5785566,1998,14088,1996,"CN","",,1,9,441,6,69,3,0,1,,0.6667,,4.3333,,,,
5894770,1999,14354,1997,"CN","",,1,,82,5,51,4,0,1,,0.625,,7.5,,,, 复制代码
2、新版0.21.x及之后的版本:
public class TestwithMultipleOutputs extends Configured implements Tool {
public static class MapClass extends Mapper<LongWritable,Text,Text,IntWritable> {
private MultipleOutputs<Text,IntWritable> mos;
protected void setup(Context context) throws IOException,InterruptedException {
mos = new MultipleOutputs<Text,IntWritable>(context);
}
public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException{
String line = value.toString();
String[] tokens = line.split("-");
mos.write("MOSInt",new Text(tokens[0]), new IntWritable(Integer.parseInt(tokens[1]))); //(第一处)
mos.write("MOSText", new Text(tokens[0]),tokens[2]); //(第二处)
mos.write("MOSText", new Text(tokens[0]),line,tokens[0]+"/"); //(第三处)同时也可写到指定的文件或文件夹中
}
protected void cleanup(Context context) throws IOException,InterruptedException {
mos.close();
}
}
public int run(String[] args) throws Exception {
Configuration conf = getConf();
Job job = new Job(conf,"word count with MultipleOutputs");
job.setJarByClass(TestwithMultipleOutputs.class);
Path in = new Path(args[0]);
Path out = new Path(args[1]);
FileInputFormat.setInputPaths(job, in);
FileOutputFormat.setOutputPath(job, out);
job.setMapperClass(MapClass.class);
job.setNumReduceTasks(0);
MultipleOutputs.addNamedOutput(job,"MOSInt",TextOutputFormat.class,Text.class,IntWritable.class);
MultipleOutputs.addNamedOutput(job,"MOSText",TextOutputFormat.class,Text.class,Text.class);
System.exit(job.waitForCompletion(true)?0:1);
return 0;
}
public static void main(String[] args) throws Exception {
int res = ToolRunner.run(new Configuration(), new TestwithMultipleOutputs(), args);
System.exit(res);
}
} 复制代码
测试的数据:
abc-1232-hdf
abc-123-rtd
ioj-234-grjth
ntg-653-sdgfvd
kju-876-btyun
bhm-530-bhyt
hfter-45642-bhgf
bgrfg-8956-fmgh
jnhdf-8734-adfbgf
ntg-68763-nfhsdf
ntg-98634-dehuy
hfter-84567-drhuk
结果截图:(结果输出到/test/testMOSout)
PS:遇到的一个问题:
如果没有mos.close(), 程序运行中会出现异常:
12/05/21 20:12:47 WARN hdfs.DFSClient: DataStreamer Exception:
org.apache.hadoop.ipc.RemoteException:org.apache.hadoop.hdfs.server.namenode.LeaseExpiredException: No lease on
/test/mosreduce/_temporary/_attempt_local_0001_r_000000_0/h-r-00000 File does not exist. [Lease. Holder: DFSClient_-352105532, pendingcreates: 5]