在eclipse上安装hadoop2.2.0插件

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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。
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4、配置Map/Reduce Locations。

在Window–>Show View->other…，在MapReduce Tools中选择Map/Reduce Locations。
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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。
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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<Object,Text,Text,IntWritable>{        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<Text,IntWritable,Text,IntWritable>{        private IntWritable result = new IntWritable();        public void reduce(Text key,Iterable<IntWritable> 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

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