在eclipse上安装hadoop2.2.0插件

1、安装环境

系统：centos6.5
hadoop2.2.0
eclipse:mars.1Release（4.5.1）

2、插件的安装

下载hadoop2.2.0的eclipse插件，解压之后放到eclipse的plugin目录下，重启eclipse。

3、配置hadoop installation directory

如果安装插件成功，打开Window–>Preferens，你会发现Hadoop Map/Reduce选项，在这个选项里你需要配置Hadoop installation
directory。配置完成后退出。

4、配置Map/Reduce Locations。

在Window–>Show View->other…，在MapReduce Tools中选择Map/Reduce Locations。


在Map/Reduce Locations（Eclipse界面的正下方）中新建一个Hadoop Location。在这个View中，点击鼠标右键–>New Hadoop Location。在弹出的对话框中你需要配置Location name，可任意填，如Hadoop，以及Map/Reduce Master和DFS Master。这里面的Host、Port分别为你在mapred-site.xml、core-site.xml中配置的地址及端口。



完成后可以看到对应的文件。我的这两个文件中配置如下：

在左边就可以看到hdfs中的文件了。

5、运行一个wordcount项目测试

package edu.njupt.lqf;

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());
            System.out.println("value is what?"+value.toString());
            System.out.println("key is what?"+key.toString());
            while(itr.hasMoreElements()){
                word.set(itr.nextToken());
                context.write(word, one);
                System.out.println(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(IntWritable val:values){
                sum +=val.get();
            }
            result.set(sum);
            context.write(key, result);
        }
    }

    public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException{
        String[] dir= new String[2];
        dir[0] = "hdfs://master1:8020/data/test";
        dir[1] = "hdfs://master1:8020/output";
        Configuration conf = new Configuration();
        String[] otherArgs = new GenericOptionsParser(conf,dir).getRemainingArgs();
        for(String s:otherArgs){
            System.out.println(s);
        }
        if(otherArgs.length !=2){
            System.out.println("error");
            System.exit(2);
        }
        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(otherArgs[0])); //
        FileOutputFormat.setOutputPath(job,new Path(otherArgs[1]));
        System.out.println(job.waitForCompletion(true)?0:1);
    }
}

右键选择run ->java application ，如果执行成功刷新下hdfs的目录会出现 /output目录 结果就在part-r-00000文件