創建Hadoop java示例

Question

我知道這個問題已經被問過，但我似乎無法弄清楚。我有一個使用hadoop的單節點集羣設置，可以正常工作。我試圖編譯WordCount.java例如：

import java.io.IOException; 
import java.util.*; 

import org.apache.hadoop.fs.Path; 
import org.apache.hadoop.conf.*; 
import org.apache.hadoop.io.*; 
import org.apache.hadoop.mapred.*; 
import org.apache.hadoop.util.*; 

public class WordCount { 

    public static class Map extends MapReduceBase implements Mapper<LongWritable, Text, Text, IntWritable> { 
    private final static IntWritable one = new IntWritable(1); 
    private Text word = new Text(); 

    public void map(LongWritable key, Text value, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException { 
     String line = value.toString(); 
     StringTokenizer tokenizer = new StringTokenizer(line); 
     while (tokenizer.hasMoreTokens()) { 
     word.set(tokenizer.nextToken()); 
     output.collect(word, one); 
     } 
    } 
    } 

    public static class Reduce extends MapReduceBase implements Reducer<Text, IntWritable, Text, IntWritable> { 
    public void reduce(Text key, Iterator<IntWritable> values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException { 
     int sum = 0; 
     while (values.hasNext()) { 
     sum += values.next().get(); 
     } 
     output.collect(key, new IntWritable(sum)); 
    } 
    } 

    public static void main(String[] args) throws Exception { 
    JobConf conf = new JobConf(WordCount.class); 
    conf.setJobName("wordcount"); 

    conf.setOutputKeyClass(Text.class); 
    conf.setOutputValueClass(IntWritable.class); 

    conf.setMapperClass(Map.class); 
    conf.setCombinerClass(Reduce.class); 
    conf.setReducerClass(Reduce.class); 

    conf.setInputFormat(TextInputFormat.class); 
    conf.setOutputFormat(TextOutputFormat.class); 

    FileInputFormat.setInputPaths(conf, new Path(args[0])); 
    FileOutputFormat.setOutputPath(conf, new Path(args[1])); 

    JobClient.runJob(conf); 
    } 
} 

我已經安裝了Hadoop的2.2.0到/ usr /本地/ Hadoop的/但我不能爲我的生活弄清楚什麼.jar文件我需要添加eclipse來導入org.apache.hadoop文件。我很少使用Java或eclipse，但我已將hadoop home文件夾中的每個.jar文件複製到我的eclipse工作區中的lib文件夾中，並在項目設置中添加了外部.jars。任何想法我做錯了什麼？

Answer 1

您還需要提供輸入和輸出詳細信息，以及其他可能的信息（取決於您提交的示例代碼之外完成的工作量）。

這裏是一個更詳細的教程：

• Running Hadoop from Eclipse Kepler