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主题： [转帖]在eclipse中配置hadoop插件

jie.liang

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发表于：

2013-10-18 10:36:06 | [全部帖] [楼主帖]

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1、安装插件

Eclipse Standard 4.3.1
hadoop-eclipse-plugin-1.2.1.jar

2、打开MapReduce视图

Window--->Perspecttive

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3、添加MapReduce环境

在eclipse下端，控制台旁边会多一个Tab，叫“Map/Reduce Locations”，在下面空白的地方点右键，选择“New Hadoop location...”，如图所示：

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在弹出的对话框中填写如下内容：

Location name（取个名字）
Map/Reduce Master（Job Tracker的IP和端口，根据mapred-site.xml中配置的mapred.job.tracker来填写）
DFS Master（Name Node的IP和端口，根据core-site.xml中配置的fs.default.name来填写）

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4.使用eclipse对HDFS内容进行修改

经过上一步骤，左侧“Project Explorer”中应该会出现配置好的HDFS，点击右键，可以进行新建文件夹、删除文件夹、上传文件、下载文件、删除文件等操作。

注意：每一次操作完在eclipse中不能马上显示变化，必须得刷新一下。

5、创建MapReduce工程

5.1、配置hadoop路径

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这里/User/Libo/Downloaders/eclipse/hadoop-1.2.1是拷贝的hadoop安装文件包

5.2创建工程

File -> New -> Project 选择“Map/Reduce Project”，然后输入项目名称，创建项目。插件会自动把hadoop根目录和lib目录下的所有jar包导入

5.3创建Mapper或者Reducer

File -> New -> Mapper 创建Mapper，自动继承mapred包里面的MapReduceBase并实现Mapper接口。
注意：这个插件自动继承的是mapred包里旧版的类和接口，新版的Mapper得自己写。

Reducer同理。

6、在eclipse中运行WorkCount程序

6.1 导入代码

package WordCount
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.LongWritable;
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;
public class WordCount {
      public static class TokenizerMapper extends 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, 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<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 Exception {
            Configuration conf = new Configuration();
            if (args.length != 2) {
                  System.err.println("Usage: wordcount ");
                  System.exit(2);
            }
            Job job = new Job(conf, "word count");
            job.setJarByClass(WordCount.class);
            job.setMapperClass(TokenizerMapper.class);
            job.setReducerClass(IntSumReducer.class);
            job.setMapOutputKeyClass(Text.class);
            job.setMapOutputValueClass(IntWritable.class);
            job.setOutputKeyClass(Text.class);
            job.setOutputValueClass(IntWritable.class);
            FileInputFormat.addInputPath(job, new Path(args[0]));
            FileOutputFormat.setOutputPath(job, new Path(args[1]));
            System.exit(job.waitForCompletion(true) ? 0 : 1);
      }
}

6.2、配置运行参数

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hdfs://192.168.76.2:9000/user/grid/in hdfs://192.168.76.2:9000/user/grid/out1 是部署hadoop的环境

6.3、执行时遇到报错

013-09-30 15:34:10.219 java[2477:1203] Unable to load realm info from SCDynamicStore
13/09/30 15:34:10 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
13/09/30 15:34:10 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
13/09/30 15:34:10 WARN mapred.JobClient: No job jar file set. User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
13/09/30 15:34:10 INFO input.FileInputFormat: Total input paths to process : 4
13/09/30 15:34:10 WARN snappy.LoadSnappy: Snappy native library not loaded
13/09/30 15:34:11 INFO mapred.JobClient: Running job: job_local1825526799_0001
13/09/30 15:34:11 WARN mapred.LocalJobRunner: job_local1825526799_0001
org.apache.hadoop.security.AccessControlException: org.apache.hadoop.security.AccessControlException: Permission denied: user=LiBo, access=WRITE, inode="grid":grid:supergroup:rwxr-xr-x
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at org.apache.hadoop.ipc.RemoteException.instantiateException(RemoteException.java:95)
at org.apache.hadoop.ipc.RemoteException.unwrapRemoteException(RemoteException.java:57)
at org.apache.hadoop.hdfs.DFSClient.mkdirs(DFSClient.java:1459)
at org.apache.hadoop.hdfs.DistributedFileSystem.mkdirs(DistributedFileSystem.java:362)
at org.apache.hadoop.fs.FileSystem.mkdirs(FileSystem.java:1161)
at org.apache.hadoop.mapred.FileOutputCommitter.setupJob(FileOutputCommitter.java:52)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:319)

通过” Permission denied“ 确认是读写权限文件，难道多hfds没有足够的权限？

更改hdfs读写权限：

[grid@h1 hadoop-1.2.1]$ hadoop fs -chmod -R 777 .

程序正常运行：

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