我使用Maven插件在Eclipse中使用hadoop,
我尝试做链式 map 简化功能,在第二张 map 中
KeyValueTextInputFormat.class作为输入文件类,而不是TextInputFormat.class。因为我想将“文本”作为键传递给 map ,而不是LongWritable。
当我这样做时,遇到了这个异常,我尝试了所有在stackoverflow中找到它的解决方案。
Exception in thread "main" java.lang.IncompatibleClassChangeError: Found class org.apache.hadoop.mapreduce.JobContext, but interface was expected
at org.apache.hadoop.mapreduce.lib.input.KeyValueTextInputFormat.isSplitable(KeyValueTextInputFormat.java:52)
at org.apache.hadoop.mapreduce.lib.input.FileInputFormat.getSplits(FileInputFormat.java:246)
at org.apache.hadoop.mapred.JobClient.writeNewSplits(JobClient.java:885)
驱动程序类:
Configuration conf = new Configuration(true);
// Create job1
Job job1 = new Job(conf, "job1");
job1.setJarByClass(Mapper1.class);
job1.setMapperClass(Mapper1.class);
job1.setMapOutputKeyClass(ByteWritable.class);
job1.setMapOutputValueClass(RowNumberWritable.class);
job1.setReducerClass(Reducer1.class);
job1.setNumReduceTasks(1);
job1.setOutputKeyClass(Text.class);
job1.setOutputValueClass(Text.class);
FileInputFormat.addInputPath(job1, inputPath);
job1.setInputFormatClass(TextInputFormat.class);
Path path1 = new Path(out1);
FileOutputFormat.setOutputPath(job1, path1);
job1.setOutputFormatClass(TextOutputFormat.class);
// Delete output if exists
FileSystem hdfs = FileSystem.get(conf);
if (hdfs.exists(countedPath))
hdfs.delete(countedPath, true);
// Execute the job1
int code = job1.waitForCompletion(true) ? 0 : 1;
// Create job2
Job job2 = new Job(conf, "WordPerDocument");
job2.setJarByClass(Mapper2.class);
job2.setMapperClass(Mapper2.class);
job2.setMapOutputKeyClass(WordDocumentWritable.class);
job2.setMapOutputValueClass(Text.class);
job2.setReducerClass(Reducer2.class);
job2.setOutputKeyClass(Text.class);
job2.setOutputValueClass(Text.class);
FileInputFormat.addInputPath(job2, path1);
job2.setInputFormatClass(KeyValueTextInputFormat.class);
Path path2 = new Path(ou2);
FileOutputFormat.setOutputPath(job2, path2);
job2.setOutputFormatClass(TextOutputFormat.class);
code = job2.waitForCompletion(true) ? 0 : 1;
我的进口是:
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.ByteWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.KeyValueTextInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
请,如果现在有人对这个疯狂的异常(exception)有任何想法:(
谢谢大家
最佳答案
我怀疑此错误是由此行引起的
FileOutputFormat.setOutputPath(job2, path2);
job2
是Job
对象,不属于该对象。.您应该使用TextOutputFormat.class
或类似的东西
关于java - Hadoop中的KeyValueTextInputFormat.class异常,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/42284550/