目錄
1.需要處理的數據
hello word
word count
hello MapReduce
2.創建maven項目pom.xml
<repositories>
<repository>
<id>cloudera</id>
<url>https://repository.cloudera.com/artifactory/cloudera-repos/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>org.apache.Hadoop</groupId>
<artifactId>Hadoop-client</artifactId>
<version>2.6.0-mr1-cdh5.14.0</version>
</dependency>
<dependency>
<groupId>org.apache.Hadoop</groupId>
<artifactId>Hadoop-common</artifactId>
<version>2.6.0-cdh5.14.0</version>
</dependency>
<dependency>
<groupId>org.apache.Hadoop</groupId>
<artifactId>Hadoop-hdfs</artifactId>
<version>2.6.0-cdh5.14.0</version>
</dependency>
<dependency>
<groupId>org.apache.Hadoop</groupId>
<artifactId>Hadoop-mapreduce-client-core</artifactId>
<version>2.6.0-cdh5.14.0</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.testng</groupId>
<artifactId>testng</artifactId>
<version>RELEASE</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.0</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.4.3</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<minimizeJar>true</minimizeJar>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
3.編寫map類
package com.czxy.wordCount;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import java.io.IOException;
public class WordCountMapper extends Mapper<LongWritable, Text, Text, LongWritable> {
@Override
protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
// 將 Text類型轉換爲String 類型
String s = value.toString();
// 安裝空格切分
String[] split = s.split(" ");
// 循環遍歷輸出
for (String s1 : split) {
// 輸出 key=單詞 value =1
context.write(new Text(s1), new LongWritable(1));
}
}
}
4.編寫Reduce類
package com.czxy.wordCount;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;
import java.io.IOException;
public class WordCountReduce extends Reducer<Text, LongWritable,Text,LongWritable> {
@Override
protected void reduce(Text key, Iterable<LongWritable> values, Context context) throws IOException, InterruptedException {
// 定義一個變量用來記錄單詞出現的次數
int sumCount=0;
for (LongWritable value : values) {
sumCount+=value.get();
}
// 結果數據
context.write(key, new LongWritable(sumCount));
}
}
5.編寫啓動類
package com.czxy.wordCount;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
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.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
public class WordCountDriver extends Configured implements Tool {
@Override
public int run(String[] args) throws Exception {
// 獲取job
Job job = Job.getInstance(new Configuration());
// 設置支持jar執行
job.setJarByClass(WordCountDriver.class);
// 設置執行的napper
job.setMapperClass(WordCountMapper.class);
// 設置map輸出的key類型
job.setMapOutputKeyClass(Text.class);
// 設置map輸出value類型
job.setMapOutputValueClass(LongWritable.class);
// 設置執行的reduce
job.setReducerClass(WordCountReduce.class);
// 設置reduce輸出key的類型
job.setOutputKeyClass(Text.class);
// 設置reduce輸出value的類型
job.setOutputValueClass(LongWritable.class);
// 設置文件輸入
job.setInputFormatClass(TextInputFormat.class);
TextInputFormat.addInputPath(job, new Path("./data/wordCount/"));
// 設置文件輸出
job.setOutputFormatClass(TextOutputFormat.class);
TextOutputFormat.setOutputPath(job, new Path("./outPut/wordCount/"));
// 設置啓動類
boolean b = job.waitForCompletion(true);
return b ? 0 : 1;
}
public static void main(String[] args) throws Exception {
// 調用啓動方法
ToolRunner.run(new WordCountDriver(), args);
}
}
6.執行的結果
MapReduce 1
count 1
hello 2
word 2