搭建Hadoop集群: VirtualBox+Ubuntu 14.04+Hadoop2.6.0
搭建好集群后, 在Mac下安装Eclipse并连接Hadoop集群
1. 访问集群
1.1. 修改Mac的hosts
添加Master的IP到Mac的hosts
##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1 localhost
255.255.255.255 broadcasthost
::1 localhost
192.168.56.101 Master # 添加Master的IP1.2 访问集群
Master下, 启动集群
Mac下, 打开http://master:50070/
能够成功访问, 看到集群的信息, 就可以了
2. 下载安装Eclipse
Eclipse IDE for Java Developers
http://www.eclipse.org/downloads/package...
3. 配置Eclipse
3.1 配置Hadoop-Eclipse-Plugin
3.1.1 下载Hadoop-Eclipse-Plugin
可下载 Github 上的 hadoop2x-eclipse-plugin（备用下载地址：http://pan.baidu.com/s/1i4ikIoP）
3.1.2 安装Hadoop-Eclipse-Plugin
在Applications中找个Eclise, 右键, Show Package Contents
将插件复制到plugins目录下, 然后重新打开Eclipse就可以了
3.2 连接Hadoop集群
3.2.1 配置Hadoop安装目录
将Hadoop安装包解压到任何目录, 不用做任何配置, 然后在Eclipse中指向该目录即可
3.2.2 配置集群地址
点击右上角的加号
添加Map/Reduce视图
选择Map/Reduce Locations, 然后右键, 选择New Hadoop location
需要改Location name, Host, DFS Master下的Port, User name ( Master会引用Mac中的hosts配置的IP ), 完成后, Finish
3.2.3 查看HDFS
查看是否可以直接访问HDFS
4. 集群中运行WordCount
4.1 创建项目
File -> New -> Other -> Map/Reduce Project
输入项目名: WordCount, 然后点击, Finish
4.2 创建类
创建一个类, 报名org.apache.hadoop.examples, 类名: WordCount
4.3 WordCount代码
复制下面的代码到WordCount.java中
package org.apache.hadoop.examples;
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());
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();
String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
if (otherArgs.length != 2) {
System.err.println("Usage: wordcount <in> <out>");
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.exit(job.waitForCompletion(true) ? 0 : 1);
}
}4.4 配置Hadoop参数
将所有修改过的配置文件和log4j.properties, 复制到src目标下
这里我复制了slaves, core-site.xml, hdfs-site.xml, mapred-site.xml, yarn-site.xml
4.4 配置HDFS输入输出路径
鼠标移动到WordCount.java上, 右键, Run As, Java Application
此时, 程序不会正常运行. 再次右键, Run As, 选择Run Configurations
填入输入输出路径 (空格分割)
配置完成后点击, Run. 此时会出现, Permission denied
5. 运行中出现的问题
5.1 Permission denied
没有权限访问HDFS
# 假设Mac的用户名为hadoop
groupadd supergroup # 添加supergroup组
useradd -g supergroup hadoop # 添加hadoop用户到supergroup组
# 修改hadoop集群中hdfs文件的组权限, 使属于supergroup组的所有用户都有读写权限
hadoop fs -chmod 777 /6. 查看Hadoop源码
6.1 下载源码
http://apache.claz.org/hadoop/common/had...
6.2 链接源码
右上角的搜索框中, 搜索Open Type
输入NameNode, 选择NameNode, 发现看不了源码
点击Attach Source -> External location -> External Floder