java:5: error: package org.apache.hadoop.conf does not

异常描述

异常提示

WordCount.java:4: error: package org.apache.hadoop.conf does not exist
import org.apache.hadoop.conf.Configuration;
^
WordCount.java:5: error: package org.apache.hadoop.fs does not exist
import org.apache.hadoop.fs.Path;
^
WordCount.java:6: error: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.IntWritable;
^
WordCount.java:7: error: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.Text;
^
WordCount.java:8: error: package org.apache.hadoop.mapreduce does not exist
import org.apache.hadoop.mapreduce.Job;
^
WordCount.java:9: error: package org.apache.hadoop.mapreduce does not exist
import org.apache.hadoop.mapreduce.Mapper;
^
WordCount.java:10: error: package org.apache.hadoop.mapreduce does not exist
import org.apache.hadoop.mapreduce.Reducer;
^
WordCount.java:11: error: package org.apache.hadoop.mapreduce.lib.input does not exist
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
^
WordCount.java:12: error: package org.apache.hadoop.mapreduce.lib.output does not exist
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
^
WordCount.java:13: error: package org.apache.hadoop.util does not exist
import org.apache.hadoop.util.GenericOptionsParser;
^
WordCount.java:38: error: cannot find symbol
public static class IntSumReducer extends Reducer<Text, IntWritable, Text, IntWritable>

问题原因：

您使用的是jdk,Javac编译MapRedce，他肯定不含Hadoop的依赖包!对么。

解决方案：

export CLASSPATH=
.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$CLASSPATH
export CLASSPATH=
.:$HADOOP_HOME/share/hadoop/common/hadoop-common-2.2.0:$HADOOP_HOME/share/hadoop/mapreduce/hadoop-mapreduce-client-core-2.2.0.jar:$HADOOP_HOME/share/hadoop/common/lib/commons-cli-1.2.jar:$CLASSPATH

注意：

1: 注意包路径，注意版本。
2: 新窗口并不会加载classpath。
3：更改后刷新文件：source /etc/profile