有人知道为什么我会收到此错误吗？我看过很多其他类似的帖子，但其中大多数不适用于我，我也尝试了发布的一些确实适用于我的解决方案，但它们不起作用，我确信我只是错过了一些愚蠢的东西， 谢谢您的帮助
chris@chrisUHadoop:/usr/local/hadoop-1.0.3/build$ hadoop MaxTemperature 1901 output4
12/07/03 17:23:08 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
12/07/03 17:23:08 INFO input.FileInputFormat: Total input paths to process : 1
12/07/03 17:23:08 INFO util.NativeCodeLoader: Loaded the native-hadoop library
12/07/03 17:23:08 WARN snappy.LoadSnappy: Snappy native library not loaded
12/07/03 17:23:09 INFO mapred.JobClient: Running job: job_201207031642_0005
12/07/03 17:23:10 INFO mapred.JobClient: map 0% reduce 0%
12/07/03 17:23:28 INFO mapred.JobClient: Task Id : attempt_201207031642_0005_m_000000_0, Status : FAILED
java.io.IOException: Type mismatch in key from map: expected org.apache.hadoop.io.Text, recieved org.apache.hadoop.io.LongWritable
at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1014)
at org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:691)
at org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)
at org.apache.hadoop.mapreduce.Mapper.map(Mapper.java:124)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
at org.apache.hadoop.mapred.Child.main(Child.java:249)
Program:
import java.io.IOException;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
public class MaxTemperatureMapper extends Mapper<LongWritable, Text, Text, IntWritable>{
private static final int MISSING = 9999;
@Override
public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException
{
String line = value.toString();
String year = line.substring(15,19);
int airTemperature;
if (line.charAt(87) == '+')
{
airTemperature = Integer.parseInt(line.substring(88,92));
}
else
{
airTemperature = Integer.parseInt(line.substring(87,92));
}
String quality = line.substring(92,93);
if (airTemperature != MISSING && quality.matches("[01459]"))
{
context.write(new Text(year), new IntWritable(airTemperature));
}
}
}
import java.io.IOException;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;
public class MaxTemperatureReducer extends Reducer<Text, IntWritable, Text, IntWritable>
{
@Override
public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException
{
int maxValue = Integer.MIN_VALUE;
for (IntWritable value : values)
{
maxValue = Math.max(maxValue, value.get());
}
context.write(key, new IntWritable(maxValue));
}
}
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
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.output.FileOutputFormat;
public class MaxTemperature
{
public static void main(String[] args) throws Exception
{
if (args.length != 2)
{
System.out.println("Usage: MaxTemperature <input path> <output path>");
System.exit(-1);
}
Job job = new Job();
job.setJarByClass(MaxTemperature.class);
job.setJobName("Max temperature");
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
