Hadoop2.7.5WordCount程序代码

package MapReduce;


import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
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;
import java.util.StringTokenizer;


/**
 * MapReduce开发WordCount应用程序
 * */
public class MyWordCount {
	

    /**
     *
     * Map:读取输入的文件
     * */
    public static class MyMapper extends Mapper<LongWritable, Text, Text, IntWritable> {
    	private final IntWritable one = new IntWritable(1); 
    	private Text word = new Text();
    	
        @Override
        protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
                     
            //获得每行数据
            String line = value.toString();
            
            //分割字符串
            //String[] words = line.split(" ");
            StringTokenizer stringTokenizer = new StringTokenizer(line);
            
            //遍历
            while (stringTokenizer.hasMoreTokens()) {
            	//获取每个值
				String wordValue = stringTokenizer.nextToken();
				
				//设置map输出的key值
				word.set(wordValue);
				
				//上下文输出map的key和value
				context.write(word, one);
			}
        }
    }

    /**
     * Reduce
     * */
    public  static class MyReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
        @Override
        protected void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
        	//用于累加的变量
            int sum =  0;
            for(IntWritable value: values) {
                sum += value.get();
            }

            context.write(key, new IntWritable(sum));
        }
    }

    /**
     * 定义Driver类
     * */

    public static void main(String[] args) throws Exception {
    	//运行在eclipse端需要以下参数
    	args = new String[] {"hdfs://192.168.0.31:9000/wc/input","hdfs://192.168.0.31:9000/wc/output"}; 
    	
    	//获取配置信息
        Configuration configuration = new Configuration();
        configuration.set("fs.defaultFS",  "hdfs://192.168.0.31:9000");
        String[] otherArgs = new GenericOptionsParser(configuration , args).getRemainingArgs();
        if(otherArgs.length != 2) {
        	System.err.println("Usage:wordcount <in> <out>");
        	System.exit(2);       	
        }
        
        //创建job并且命名
        Job job = Job.getInstance(configuration, "mywordcount");

        //1.设置job运行的类
        job.setJarByClass(MyWordCount.class);

       // FileInputFormat.setInputPaths(job, new Path(args[0]));

        //2.设置Map和reduce类
        job.setMapperClass(MyMapper.class);
        job.setReducerClass(MyReducer.class);
        
        
        //3.设置输入输出的文件目录
        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
        
        
        
        //4.设置输出结果的key和value类型
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(IntWritable.class);
         
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);

        //5.提交job等待运行结果，并在客户端显示运行信息
        boolean isSuccess = job.waitForCompletion(true);
        
        //结束程序
        System.exit(isSuccess ? 0 : 1);
    }
}