使用Maven搭建Hadoop开发环境

 4.0.0
 my.hadoopstudy
 hadoopstudy
 jar
 1.0-SNAPSHOT
 hadoopstudy
 http://maven.apache.org

 
 
  org.apache.hadoop
  hadoop-common
  2.5.1
 
 
  org.apache.hadoop
  hadoop-hdfs
  2.5.1
 
 
  org.apache.hadoop
  hadoop-client
  2.5.1
 

 
  junit
  junit
  3.8.1
  test
 
 

package my.hadoopstudy.dfs;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;

import java.io.InputStream;
import java.net.URI;

public class Test {
 public static void main(String[] args) throws Exception {
 String uri = "hdfs://9.111.254.189:9000/";
 Configuration config = new Configuration();
 FileSystem fs = FileSystem.get(URI.create(uri), config);

 // 列出hdfs上/user/fkong/目录下的所有文件和目录
 FileStatus[] statuses = fs.listStatus(new Path("/user/fkong"));
 for (FileStatus status : statuses) {
  System.out.println(status);
 }

 // 在hdfs的/user/fkong目录下创建一个文件，并写入一行文本
 FSDataOutputStream os = fs.create(new Path("/user/fkong/test.log"));
 os.write("Hello World!".getBytes());
 os.flush();
 os.close();

 // 显示在hdfs的/user/fkong下指定文件的内容
 InputStream is = fs.open(new Path("/user/fkong/test.log"));
 IOUtils.copyBytes(is, System.out, 1024, true);
 }
}

package my.hadoopstudy.mapreduce;

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;

import java.io.IOException;

public class EventCount {

 public static class MyMapper extends Mapper{
 private final static IntWritable one = new IntWritable(1);
 private Text event = new Text();

 public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
  int idx = value.toString().indexOf(" ");
  if (idx > 0) {
  String e = value.toString().substring(0, idx);
  event.set(e);
  context.write(event, one);
  }
 }
 }

 public static class MyReducer 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 Exception {
 Configuration conf = new Configuration();
 String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
 if (otherArgs.length < 2) {
  System.err.println("Usage: EventCount  ");
  System.exit(2);
 }
 Job job = Job.getInstance(conf, "event count");
 job.setJarByClass(EventCount.class);
 job.setMapperClass(MyMapper.class);
 job.setCombinerClass(MyReducer.class);
 job.setReducerClass(MyReducer.class);
 job.setOutputKeyClass(Text.class);
 job.setOutputValueClass(IntWritable.class);
 FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
 FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
 System.exit(job.waitForCompletion(true) ? 0 : 1);
 }
}