Java Hadoop应用程序找不到Reducer
我正在尝试制作一个mapreduce应用程序,该应用程序从Hbase表读取数据,并将作业结果写入文本文件。我的驱动程序代码如下所示:Java Hadoop应用程序找不到Reducer,java,hadoop,hbase,reducers,Java,Hadoop,Hbase,Reducers,我正在尝试制作一个mapreduce应用程序,该应用程序从Hbase表读取数据,并将作业结果写入文本文件。我的驱动程序代码如下所示: Configuration conf = HBaseConfiguration.create(); Job job = Job.getInstance (conf, "mr test"); job.setJarByClass(Driverclass.class); job.setCombinerClass(reducername.c
Configuration conf = HBaseConfiguration.create();
Job job = Job.getInstance (conf, "mr test");
job.setJarByClass(Driverclass.class);
job.setCombinerClass(reducername.class);
job.setReducerClass(reducername.class);
Scan scan = new Scan();
scan.setCaching(500);
scan.setCacheBlocks(false);
String qualifier = "qualifname"; // comma seperated
String family= "familyname";
scan.addColumn(Bytes.toBytes(family), Bytes.toBytes(qualifier));
TableMapReduceUtil.initTableMapperJob("tablename",
scan,
mappername.class,
Text.class, Text.class,
job);
调用initTableMapperJob时,我得到一个ClassNotFoundException:class reducername not found
该类在同一个包中的另一个java文件中定义。我使用了几乎相同的配置来尝试常见的wordcount示例,效果很好。然后我改变了映射器的类型和配置方式,我得到了这个错误。有人能帮我吗
编辑:减速器类的代码为:
package mr.roadlevelmr;
import java.io.IOException;
import java.util.ArrayList;
import java.util.StringTokenizer;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.Reducer;
public class reducername extends Reducer <Text, Text, Text, Text>{
private Text result= new Text();
public void reduce (Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException{
ArrayList<String> means = new ArrayList<String>();
for (Text val : values){
means.add(String.valueOf(val.getBytes()));
}
result.set(newMean(means));
context.write(key, result);
}
包mr.roadlevelmr;
导入java.io.IOException;
导入java.util.ArrayList;
导入java.util.StringTokenizer;
导入org.apache.hadoop.io.*;
导入org.apache.hadoop.mapreduce.Reducer;
公共类reducername扩展了Reducer{
私有文本结果=新文本();
公共void reduce(文本键、Iterable值、上下文上下文)引发IOException、InterruptedException{
ArrayList意味着=新的ArrayList();
用于(文本值:值){
means.add(String.valueOf(val.getBytes());
}
结果集(新均值(均值));
编写(键、结果);
}
您应该按如下方式使用Map reduce util:
TableMapReduceUtil.initTableMapperJob("tablename",
scan,
mappername.class,
Text.class, Text.class,
job);Ok think I found the issue!
然后添加减速器和合路器
job.setCombinerClass(reducername.class);
job.setReducerClass(reducername.class);
boolean b = job.waitForCompletion(true);
不是将reducer添加到表映射器作业中,而是哪一行引发异常您可以发布reducer类的基本结构吗?嗨,Peter,这是引发异常的最后一行。我用reducer类编辑问题是的,它们在不同的java文件中,但在相同的包中您尝试过下面的提示吗?