9.在yarn运行wordcount程序

1.WordMapper:

public class WordcountMap extends Mapper<LongWritable, Text, Text, IntWritable> {

	@Override
	protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
		// TODO Auto-generated method stub
		//1.获取数据
		String line = value.toString();
		//2.数据分切
		String [] lin = line.split(" ");
		//3.存到集合去
		for(String word : lin) {
			context.write(new Text(word), new IntWritable(1));
			
		}
		
	}

}

2.Wordreducer

public class WordcountReduce extends Reducer<Text, IntWritable, Text, IntWritable>{

	@Override
	protected void reduce(Text Key, Iterable<IntWritable> value,Context context) throws IOException, InterruptedException {
		// TODO Auto-generated method stub
		//1.统计单词出现次数
		int sum = 0;
		
		//2.累加求和
		for(IntWritable in : value) {
			sum+=in.get();
		}
		
		
		//3.写入
		context.write(Key, new IntWritable(sum));
	}
	
	

}

3.WordDrive

public class WordcountDriver {

	public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
		// TODO Auto-generated method stub
		//构建任务
		Configuration conf = new Configuration();
		Job job = Job.getInstance(conf);
		
		//获取jar包
		job.setJarByClass(WordcountDriver.class);
		
		//获取自定义的map,reduce
		job.setMapperClass(WordcountMap.class);
		job.setReducerClass(WordcountReduce.class);
		//设置map数据类型
		job.setMapOutputKeyClass(Text.class);
		job.setMapOutputValueClass(IntWritable.class);
		
		//设置输出类型
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(IntWritable.class);
		//给任务路径
		FileInputFormat.setInputPaths(job, new Path("/in1019"));
		FileOutputFormat.setOutputPath(job, new Path("/out02"));
		
		boolean fs = job.waitForCompletion(true);
		
		System.out.println(fs);
	}

}

4.导出jar包

File->Export->JAR file

5.在yarn集群运行

hadoop jar wc.jar com.mr.wc.WordcountDriver

6.在集群上运行

1)需要配置mr的配置文件，默认是在本地的，不然一直是本地运行
hdfs-site.xml

<configuration>
        <property>
        <name>mapreduce.framework.name</name>
        <value>yarn</value>
        </property>
</configuration>

注意改之前把模板文件保存下，免得太乱后不知道咋整了