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实验目的：

1.掌握MapReduce的基本编程流程；

2.掌握MapReduce序列化的使用；

实验内容：

一、在本地创建名为MapReduceTest的Maven工程，在pom.xml中引入相关依赖包，配置log4j.properties文件，搭建windwos开发环境。 编程实现以下内容：

（1）创建com.nefu.(xingming).maxcount包，编写wordcountMapper、Reducer、Driver三个类，实现统计每个学号的最高消费。

输入数据data.txt格式如下：

          序号 \t 学号 \t  日期  \t  消费总额

输出数据格式要求如下：

          学号  \t  最高消费 

ZnMapper.java

package com.nefu.zhangna.maxcount;import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;import java.io.IOException;public class ZnMapper extends Mapper<LongWritable, Text,Text, IntWritable> {private Text outk=new Text();private IntWritable outv=new IntWritable();@Overridepublic void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {String line=value.toString();String[] content=line.split("\t");String schoolnumber=content[1];String totalFee=content[3];outk.set(schoolnumber);outv.set(Integer.parseInt(totalFee));context.write(outk,outv);}
}

ZnReducer.java

package com.nefu.zhangna.maxcount;import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;import java.io.IOException;public class ZnReducer extends Reducer<Text,IntWritable,Text, IntWritable> {private IntWritable outv=new IntWritable();@Overrideprotected void  reduce(Text key,Iterable<IntWritable> values,Context context) throws IOException, InterruptedException {int total=0;for (IntWritable value:values){if(value.get()>total)total=value.get();}outv.set(total);context.write(key,outv);}
}

ZnDriver.java

package com.nefu.zhangna.maxcount;import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.CombineTextInputFormat;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;public class ZnDriver {public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException, URISyntaxException {Configuration configuration=new Configuration();Job job=Job.getInstance(configuration);//FileSystem fs=FileSystem.get(new URI("hdfs://hadoop101:8020"),configuration,"hadoop");//fs.copyFromLocalFile(new Path("D://mapreducetest//data.txt"),new Path("/zn/data.txt"));job.setJarByClass(ZnDriver.class);job.setMapperClass(ZnMapper.class);job.setReducerClass(ZnReducer.class);job.setMapOutputKeyClass(Text.class);job.setMapOutputValueClass(IntWritable.class);//job.setOutputKeyClass(Text.class);//job.setOutputValueClass(StudentBean.class);// job.setInputFormatClass(CombineTextInputFormat.class);   //否则默认是TextInputFormat.class//CombineTextInputFormat.setMaxInputSplitSize(job,4194304);   //设4MFileInputFormat.setInputPaths(job,new Path("D:\\mapreducetest\\data.txt"));FileOutputFormat.setOutputPath(job,new Path("D:\\cluster\\shiyan3-1"));boolean result=job.waitForCompletion(true);System.exit(result?0:1);}
}

（2）测试上述程序，查看运行结果

原数据

mapreduce之后

（3）查看日志，共有几个切片，几个MapTask（截图）

Number of split表示有一个切片，Starting task: attempt_local649325949_0001_m_000000_0表示有一个Map Tast任务

（4）添加文件data1.txt，重新运行程序，共有几个切片，几个MapTask（截图）

可见我输入了两个文件，切片的数目为2，也就有两个Map Text任务

（5）使用CombinTextInputFormat，让data.txt,data1.txt两个文件在一个切片中

在驱动类中CombinTextInputFormat，可见只有一个切片

（6）将data.txt上传至HDFS

（7）使用maven将程序打成jar包并上传至hadoop集群运行，观察是否能正确运行。

<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.6.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>

将程序打成jar包

二、创建com.nefu.(xingming).serialize包，编写ScoreBean、Mapper、Reducer、Driver三个类，实现统计每个学号的平均成绩。并将结果按照年级分别写到三个文件中。

输入数据mydata.txt文件格式：

学号  \t  姓名  \t   成绩

输出数据格式（共3个文件）：

学号   \t  姓名  \t   平均成绩

MyPartition

package com.nefu.zhangna.serialize;import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Partitioner;public class MyPartition extends Partitioner<Text,ScoreBean > {@Overridepublic int getPartition(Text text,ScoreBean studentBean,int numPartitions) {String snum = text.toString();int partition;if (snum.contains("2021")) {partition = 0;} else if (snum.contains("2022")) {partition = 1;} else{partition=2;}return partition;}
}

Scorebean

package com.nefu.zhangna.serialize;import org.apache.hadoop.io.Writable;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;public  class ScoreBean implements Writable{private String name;private Double score;public ScoreBean(){}public String getName() {return name;}public void setName(String name) {this.name = name;}public Double getScore() {return score;}public void setScore(Double score) {this.score = score;}@Overridepublic void write(DataOutput out) throws IOException {out.writeUTF(name);out.writeDouble(score);}@Overridepublic  void readFields(DataInput in) throws IOException {this.name=in.readUTF();this.score=in.readDouble();}@Overridepublic String toString(){return this.name+"\t"+this.score;}
}

ZnMapper1

package com.nefu.zhangna.serialize;import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;import java.io.IOException;public class ZnMapper1 extends Mapper<LongWritable, Text, Text,ScoreBean> {private Text outk=new Text();private ScoreBean outv=new ScoreBean();@Overrideprotected void map(LongWritable key,Text value,Context context) throws IOException, InterruptedException {String line=value.toString();String[] content=line.split("\t");String  schoolnumber=content[0];String name=content[1];String score=content[2];outk.set(schoolnumber);outv.setName(name);outv.setScore(Double.parseDouble(score));context.write(outk,outv);}
}

ZnReducer1

package com.nefu.zhangna.serialize;import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;import java.io.IOException;public class ZnReducer1 extends Reducer<Text, ScoreBean,Text,ScoreBean> {private ScoreBean outv=new ScoreBean();@Overrideprotected void reduce(Text key,Iterable<ScoreBean> values,Context context) throws IOException, InterruptedException {double score=0;int sum=0;String name = null;for (ScoreBean value:values){sum=sum+1;score=score+value.getScore();name=value.getName();}outv.setName(name);outv.setScore(score/sum);context.write(key,outv);}
}

ZnDriver1

package com.nefu.zhangna.serialize;import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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;import java.io.IOException;public class ZnDriver1 {public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {Configuration configuration=new Configuration();Job job=Job.getInstance(configuration);job.setJarByClass(ZnDriver1.class);job.setMapperClass(ZnMapper1.class);job.setReducerClass(ZnReducer1.class);job.setMapOutputKeyClass(Text.class);job.setOutputValueClass(ScoreBean.class);job.setOutputKeyClass(Text.class);job.setOutputValueClass(ScoreBean.class);job.setPartitionerClass(MyPartition.class);job.setNumReduceTasks(3);FileInputFormat.setInputPaths(job,new Path("D:\\mapreducetest\\mydata.txt"));FileOutputFormat.setOutputPath(job,new Path("D:\\cluster\\serialize"));boolean result=job.waitForCompletion(true);System.exit(result?0:1);}
}