wordcount工作流程
input-> 拆分Split->映射map->派发Shuffle->缩减reduce->output
hadoop jar /usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.3.jar wordcount 10803060234.txt /output

创新互联公司专注于辽阳县企业网站建设,成都响应式网站建设公司,商城网站建设。辽阳县网站建设公司,为辽阳县等地区提供建站服务。全流程按需规划网站，专业设计，全程项目跟踪，创新互联公司专业和态度为您提供的服务

package wordcount;

import java.io.IOException;

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.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

public class Test {

public Test() {
    // TODO Auto-generated constructor stub
}

public static void main(String[] args) throws Exception {
    // TODO Auto-generated method stub

    Configuration conf = new Configuration();
    conf.set("fs.defaultFS","hdfs://172.26.19.40:9000");
    conf.set("mapreduce.job.jar", "target/wc.jar");
    conf.set("mapreduce.framework.name", "yarn");
    conf.set("yarn.resourcemanager.hostname", "hmaster");
    conf.set("mapreduce.app-submission.cross-platform", "true");
    Job job = Job.getInstance(conf);
    job.setMapperClass(WordMapper.class);
    job.setReducerClass(WordReducer.class);

    job.setMapOutputKeyClass(Text.class);
    job.setMapOutputValueClass(IntWritable.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(LongWritable.class);

    FileInputFormat.setInputPaths(job, "");
    FileOutputFormat.setOutputPath(job, new Path(""));

    job.waitForCompletion(true);
}

}

package wordcount;

import java.io.IOException;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

public class WordMapper extends Mapper {

@Override
protected void map(LongWritable key, Text value, Mapper.Context context)
        throws IOException, InterruptedException {
    String lineValue = value.toString();
    String[] words = lineValue.split(" ");
    IntWritable cIntWritable = new IntWritable(1);
    for(String word : words) {
        context.write(new Text(word), cIntWritable);
    }
}

}

package wordcount;

import java.io.IOException;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

public class WordReducer extends Reducer {

@Override
protected void reduce(Text key, Iterable values,
        Reducer.Context context) throws IOException, InterruptedException {

     Long tmpCount = 0L;
     for(IntWritable value : values) {
         tmpCount = tmpCount + value.get();
     }

     context.write(key, new LongWritable(tmpCount));

}

}

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
4.0.0
com.skcc
wordcount
0.0.1-SNAPSHOT
wordcount
count the word

    UTF-8
    2.7.3


    
        junit
        junit
        4.12
    
    
        org.apache.hadoop
        hadoop-client
        ${hadoop.version}
    
    
        org.apache.hadoop
        hadoop-common
        ${hadoop.version}
    
    
        org.apache.hadoop
        hadoop-hdfs
        ${hadoop.version}
    

另外有需要云服务器可以了解下创新互联scvps.cn，海内外云服务器15元起步，三天无理由+7*72小时售后在线，公司持有idc许可证，提供“云服务器、裸金属服务器、高防服务器、香港服务器、美国服务器、虚拟主机、免备案服务器”等云主机租用服务以及企业上云的综合解决方案，具有“安全稳定、简单易用、服务可用性高、性价比高”等特点与优势，专为企业上云打造定制，能够满足用户丰富、多元化的应用场景需求。

文章名称：hadoopMapReducejava示例-创新互联
分享地址：http://cdweb.net/article/dhiojj.html