MapReduce运行wordcount程序

1、Eclipase里面在Maven项目下编写两个java程序代码：
①主程序代码：

public class WordCount {
	public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
		Configuration conf = new Configuration();
		String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();	
		Job job = new Job(conf,"word count");
		job.setJarByClass(WordCount.class);
		//指定Mapper类
		job.setMapperClass(TokenizerMapper.class);
		job.setCombinerClass(IntSumReducer.class);
		//指定Reducer类
		job.setReducerClass(IntSumReducer.class);
		//设置Reduce函数输出key的类型
		job.setOutputKeyClass(Text.class);
		//设置Reduce函数输出value的类型
		job.setOutputValueClass(IntWritable.class);
		//指定输入路径
		FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
		//指定输出路径
		FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
		System.out.println("OK");
		//提交任务
		System.exit(job.waitForCompletion(true) ? 0 : 1);
	}
}

②主程序引用到的代码：

public 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);
		}
	}

}

2、把主程序打成jar包放到虚拟机上运行
此处附上Maven打成jar包的方法连接：
https://blog.youkuaiyun.com/Wxp_csdn/article/details/90444949

3、将jar包上传到虚拟机根目录下后执行命令：
java -jar jar包名
执行完成即可查看运行结果。