hadoop-002中Eclipse如何运行WordCount

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1、如过提示 eclipse 无法编译 文件 ，提示对某文件无权限。

chmod -R 777 workspace

2、在eclipse中跑Ｈadoop测试用例时，出现这样的错误
Exception in thread "main" org.apache.hadoop.mapred.InvalidInputException: Input path does not exist:

原因是系统没有找到hadoop的配置文件,
　对于2.5.2就是core-site.xml
其中指定了 fs.defaultFS的配置

fs.defaultFS
hdfs://localhost:9000

解决方法：

JobConf conf = new JobConf(WordCount.class);
conf.setJobName("wordcount");
//conf.set("fs.defaultFS", "hdfs://localhost:9000");
//conf.addResource(new Path("/opt/hadoop/etc/hadoop/core-site.xml"));

任选注释掉代码其中的一行执行即可。

完整代码如下：

package com.zwh;import java.io.IOException;import java.util.StringTokenizer;import org.apache.hadoop.conf.Configuration;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.Mapper;import org.apache.hadoop.mapreduce.Reducer;import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;import org.apache.hadoop.util.GenericOptionsParser;public class WordCount {  public static class TokenizerMapper        extends Mapper{        private final static IntWritable one = new IntWritable(1);    private Text word = new Text();          public void map(Object key, Text value, Context context                    ) throws IOException, InterruptedException {      StringTokenizer itr = new StringTokenizer(value.toString());      while (itr.hasMoreTokens()) {        word.set(itr.nextToken());        context.write(word, one);      }    }  }    public static class IntSumReducer        extends Reducer {    private IntWritable result = new IntWritable();    public void reduce(Text key, Iterable values,                        Context context                       ) throws IOException, InterruptedException {      int sum = 0;      for (IntWritableval : values) {        sum += val.get();      }      result.set(sum);      context.write(key, result);    }  }  public static void main(String[] args) throws Exception {    Configuration conf = new Configuration();    conf.set("fs.defaultFS", "hdfs://localhost:9000");     Job job = new Job(conf, "word count");    job.setJarByClass(WordCount.class);    job.setMapperClass(TokenizerMapper.class);    job.setCombinerClass(IntSumReducer.class);    job.setReducerClass(IntSumReducer.class);    job.setOutputKeyClass(Text.class);    job.setOutputValueClass(IntWritable.class);    FileInputFormat.addInputPath(job, new Path("/user/root/input/"));    FileOutputFormat.setOutputPath(job,new Path("/user/root/output/wc"));    System.exit(job.waitForCompletion(true) ? 0 : 1);  }}

示意图

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