MapReduce实战-词频统计、文件合并排序

r囧r小猫 2022-10-21 03:49 130阅读 0赞

### 文章目录 ###

*  环境搭建
 *  词频统计
 *   *  输入
     *  源码
     *  输出
 *  合并
 *   *  输入
     *  源码
     *  输出
 *  排序
 *   *  输入
     *  源码
     *  输出

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# 环境搭建 #

--------------------

hadoop伪分布式集群环境，包括设置JAVA\_HOME、HADOOP\_HOME等。  
可参考[使用docker部署hadoop集群-手把手复现][docker_hadoop_-]

# 词频统计 #

--------------------

统计所有输入文件中每个单词出现的次数。  
如输入：  
file1.txt

Hello World

file2.txt

Bye World

输出：

Bye	1
    Hello 1
    World 2

## 输入 ##

1.  创建输入文件

cd /usr
    mkdir file #新建目录
    cd file
    mkdir WordCount
    cd WordCount
    echo "Hello World">file1.txt
    echo "Bye World">file2.txt #file1、2作为输入文件

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MDM0NzA4_size_16_color_FFFFFF_t_70]

1.  传入hdfs输入文件夹

hdfs dfs -mkdir -p /user/root #若无root用户文件夹则先创建
    hadoop fs -mkdir WordCount #创建一个目录（可自定义）
    hadoop fs -mkdir WordCount/input #输入文件夹
    hadoop fs -ls WordCount #查看文件
    hadoop fs -put /usr/file/WordCount/file*.txt WordCount/input #上传
    hadoop fs -ls WordCount/input
    #hadoop fs -rmr wc/output #若存在则删除输出目录

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MDM0NzA4_size_16_color_FFFFFF_t_70 1]

## 源码 ##

1.  源代码

cd /usr/file/WordCount
    vi WordCount.java

import java.io.IOException;
    import java.util.StringTokenizer;
    
    import org.apache.hadoop.conf.Configuration;
    import org.apache.hadoop.fs.Path;
    import org.apache.hadoop.io.IntWritable;
    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;
    
    public class WordCount { 
    
        public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> { 
    
            private final static IntWritable one = new IntWritable(1);
            private Text word = new Text();
    
            public void map(Object 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);
                }
            }
        }
    
        public static class IntSumReducer
                extends Reducer<Text, IntWritable, Text, IntWritable> { 
            private IntWritable result = new IntWritable();
    
            public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { 
                int sum = 0;
                for (IntWritable val : values) { 
                    sum += val.get();
                }
                result.set(sum);
                context.write(key, result);
            }
        }
    
        public static void main(String[] args) throws Exception { 
            Configuration conf = new Configuration();
            if (args.length != 2) { 
                System.err.println("usage: WordCount <in> <out>");
                System.exit(2);
            }
            Job job = Job.getInstance(conf,"WordCount");
            job.setJarByClass(WordCount.class);
            job.setMapperClass(WordCount.TokenizerMapper.class);
            job.setCombinerClass(WordCount.IntSumReducer.class);
            job.setReducerClass(WordCount.IntSumReducer.class);
            job.setOutputKeyClass(Text.class);
            job.setOutputValueClass(IntWritable.class);
            FileInputFormat.addInputPath(job, new Path(args[0]));
            FileOutputFormat.setOutputPath(job, new Path(args[1]));
            System.exit(job.waitForCompletion(true) ? 0 : 1);
        }
    }

1.  编译打包

javac WordCount.java -cp $(hadoop classpath)
    jar -cvf WordCount.jar *.class

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## 输出 ##

#hadoop jar jar包位置 主类名 参数1（输入路径） 参数2（输出路径）
    hadoop jar /usr/file/WordCount/WordCount.jar WordCount WordCount/input WordCount/output
    #查看输出
    hadoop fs -cat WordCount/output/*

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MDM0NzA4_size_16_color_FFFFFF_t_70 3]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MDM0NzA4_size_16_color_FFFFFF_t_70 4]  
附：重启步骤

exit #退出docker容器
    shutdown -r now #重启系统
    systemctl start docker #启动docker服务
    docker start hadoop1 #启动相应容器
    docker start hadoop2
    docker start hadoop3
    docker exec -it hadoop1 bash #进入主节点
    $HADOOP_HOME/sbin/./start-all.sh #启动集群

# 合并 #

--------------------

对输入文件进行合并，剔除其中重复的内容。  
如输入：  
file1.txt

20150101 x
    20150102 y
    20150103 x
    20150104 y
    20150105 z
    20150106 x

file2.txt

20150101 y
    20150102 y
    20150103 x
    20150104 z
    20150105 y

输出：

20150101 x
    20150101 y
    20150102 y
    20150103 x
    20150104 y
    20150104 z
    20150105 y
    20150105 z
    20150106 x

## 输入 ##

cd /usr/file #没有则新建一个目录
    mkdir Merge
    cd Merge
    vi file1.txt#内容就是上面的file1.txt
    vi file2.txt
    hadoop fs -mkdir Merge
    hadoop fs -mkdir Merge/input
    hadoop fs -put /usr/file/Merge/file*.txt Merge/input 
    hadoop fs -ls Merge/input

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MDM0NzA4_size_16_color_FFFFFF_t_70 5]

> （插播反爬信息 ）博主CSDN地址：[https://wzlodq.blog.csdn.net/][https_wzlodq.blog.csdn.net]

## 源码 ##

vi Merge.java
    javac Merge.java -cp $(hadoop classpath)
    jar -cvf Merge.jar *.class

import org.apache.hadoop.conf.Configuration;
    import org.apache.hadoop.fs.Path;
    import org.apache.hadoop.io.Text;
    import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
    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 java.io.IOException;
    
    public class Merge { 
    
        public static class Map extends Mapper<Object, Text, Text, Text> { 
            private static Text text = new Text();
    
            public void map(Object key, Text value, Context content) throws IOException, InterruptedException { 
                text = value;
                content.write(text, new Text(""));
            }
        }
    
        public static class Reduce extends Reducer<Text, Text, Text, Text> { 
            public void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException { 
                context.write(key, new Text(""));
            }
        }
    
        public static void main(String[] args) throws Exception { 
            Configuration conf = new Configuration();
            if (args.length != 2) { 
                System.err.println("usage: Merge <in> <out>");
                System.exit(2);
            }
            Job job = Job.getInstance(conf,"Merge");
            job.setJarByClass(Merge.class);
            job.setMapperClass(Merge.Map.class);
            job.setReducerClass(Merge.Reduce.class);
            job.setOutputKeyClass(Text.class);
            job.setOutputValueClass(Text.class);
            FileInputFormat.addInputPath(job, new Path(args[0]));
            FileOutputFormat.setOutputPath(job, new Path(args[1]));
            System.exit(job.waitForCompletion(true) ? 0 : 1);
        }
    }

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## 输出 ##

hadoop jar /usr/file/Merge/Merge.jar Merge Merge/input Merge/output
    hadoop fs -cat Merge/output/*

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MDM0NzA4_size_16_color_FFFFFF_t_70 7]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MDM0NzA4_size_16_color_FFFFFF_t_70 8]

# 排序 #

--------------------

读取所有输入文件中的整数，进行升序排序后，输出到一个新文件。  
输入：  
file1.txt

33
    37
    12
    40

file2.txt

4
    16
    39
    5

file3.txt

1
    45
    25

输出：  
输出的数据格式为每行两个整数，第一个整数位第二个整数的排序为此，第二个整数为原待排列的整数。

1 1
    2 4
    3 5
    4 12
    5 16
    6 25
    7 33
    8 37
    9 39
    10 40
    11 45

## 输入 ##

cd /usr/file #没有则新建一个目录
    mkdir Sort
    cd Sort
    vi file1.txt#内容就是上面的file1.txt
    vi file2.txt
    vi file3.txt
    hadoop fs -mkdir Sort
    hadoop fs -mkdir Sort/input
    hadoop fs -put /usr/file/Sort/file*.txt Sort/input 
    hadoop fs -ls Sort/input

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MDM0NzA4_size_16_color_FFFFFF_t_70 9]

## 源码 ##

vi Sort.java
    javac Sort.java -cp $(hadoop classpath)
    jar -cvf Sort.jar *.class

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.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;
    
    public class Sort { 
        public static class Map extends Mapper<Object,Text,IntWritable,IntWritable>{ 
            private static IntWritable data=new IntWritable();
            public void map(Object key,Text value,Context context) throws IOException, InterruptedException{ 
                String line=value.toString();
                data.set(Integer.parseInt(line));
                context.write(data, new IntWritable(1));
            }
        }
        public static class Reduce extends Reducer<IntWritable,IntWritable,IntWritable,IntWritable>{ 
            private static IntWritable linenum=new IntWritable(1);
            public void reduce(IntWritable key,Iterable <IntWritable>values,Context context) throws IOException, InterruptedException{ 
                for(IntWritable num:values){ 
                    context.write(linenum, key);
                    linenum=new IntWritable(linenum.get()+1);
                }
    
            }
        }
    
        public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException{ 
            Configuration conf=new Configuration();
            if(args.length!=2){ 
                System.err.println("Usage:Sort <in> <out>");
                System.exit(2);
            }
            Job job=Job.getInstance(conf,"Sort");
            job.setJarByClass(Sort.class);
            job.setMapperClass(Sort.Map.class);
            job.setReducerClass(Sort.Reduce.class);
            job.setOutputKeyClass(IntWritable.class);
            job.setOutputValueClass(IntWritable.class);
            FileInputFormat.addInputPath(job,new Path(args[0]));
            FileOutputFormat.setOutputPath(job,new Path(args[1]));
            System.exit(job.waitForCompletion(true)?0:1);
        }
    }

![在这里插入图片描述][2021050517243413.png]

## 输出 ##

hadoop jar /usr/file/Sort/Sort.jar Sort Sort/input Sort/output
    hadoop fs -cat Sort/output/*

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MDM0NzA4_size_16_color_FFFFFF_t_70 10]

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