Hadoop 1.0.4 安装配置和 wordcount

环境如下：

ubuntu-12.04.2-server-amd64

hadoop-1.0.4

VirtualBox

1、在VBox中安装UbuntuServer，

用户名和密码都是hadoop，安装完成后，克隆两份，这样就有三台机器，一台master，两台slave。克隆后的slave打开不能上网，原因是克隆的时候，“重新初始化所有网卡的MAC地址”,而Ubuntu系统中网卡缓存中的MAC地址也新的MAC地址不一致，解决方法是在克隆后的机器中删除一个文件，使用如下命令：

sudoconfigurationpropertynamenamevaluevaluepropertyconfigurationconfigurationpropertynamenamevaluevaluepropertypropertynamenamevaluevaluepropertypropertynamenamevaluevaluepropertyconfigurationconfigurationpropertynamenamevaluevaluepropertypropertynamenamevaluevaluepropertyconfigurationLongWritable,TextTextIntWritable>Text, IntWritable> output, Reporter reporter) throws IOException {
       int sum = 0;
       while (values.hasNext()) {
         sum += values.next().get();
       }
       output.collect(key, new IntWritable(sum));
     }
   }

   public static void main(String[] args) throws Exception {
     JobConf conf = new JobConf(WordCount.class);
     conf.setJobName("wordcount");

     conf.setOutputKeyClass(Text.class);
     conf.setOutputValueClass(IntWritable.class);

     conf.setMapperClass(Map.class);
     conf.setCombinerClass(Reduce.class);
     conf.setReducerClass(Reduce.class);

     conf.setInputFormat(TextInputFormat.class);
     conf.setOutputFormat(TextOutputFormat.class);

     FileInputFormat.setInputPaths(conf, new Path(args[0]));
     FileOutputFormat.setOutputPath(conf, new Path(args[1]));

     JobClient.runJob(conf);
   }
}