WordCount类代码：
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.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
public class WordCount {
public static void main(String[] args) throws Exception {
//定义配置对象
Configuration conf = new Configuration();
//定义一个工作对象
Job job = Job.getInstance(conf);
//获取map的一个对象
job.setMapperClass(WordCountMap.class);
//指定map阶段的一个输出key
job.setMapOutputKeyClass(Text.class);
//指定map阶段输出的values类型
job.setMapOutputValueClass(IntWritable.class);
//指定map阶段的输入文件
FileInputFormat.setInputPaths(job,new Path("D:\\代码\\大二下\\Hadoop\\4、MapReduce_Reduce\\123.txt"));
//获取reduce的类
job.setReducerClass(WordCountReduce.class);
//指定reduce阶段的一个输出的key
job.setOutputKeyClass(Text.class);
//指定reduce阶段输出的values类型
job.setOutputValueClass(IntWritable.class);
//指定reduce阶段的输出文件
FileOutputFormat.setOutputPath(job,new Path("D:\\代码\\大二下\\Hadoop\\4、MapReduce_Reduce\\456.txt"));
job.waitForCompletion(true);
}
}
WordMap类代码：
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 WordCountMap extends Mapper {
@Override
protected void map(LongWritable key, Text value,Context context) throws IOException, InterruptedException {
//读取每行文本
String line = value.toString();
//splite拆分每行
String[] words = line.split(" ");
//取出每个单词
for (String word:
words) {
//将单词转为Text类型
Text wordText = new Text(word);
//将1转变成IntWritable
IntWritable outValue = new IntWritable(1);
//写出每个单词，跟对应1
context.write(wordText, outValue);
}
}
}
WordReduce类代码：
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;
import java.io.IOException;
/*
* Text 输入的字符串类型，序列化
* IntWritable 输入一串1，序列化
* Text 输出的字符串类型，序列化
* IntWritable 输出的求和数组，序列化
* */
public class WordCountReduce extends Reducer {
/*
* key 输入单词名字
* values 输入一串1
* context 输出的工具
* */
@Override
protected void reduce(Text key, Iterable values, Context context) throws IOException, InterruptedException {
int sum=0;
for(IntWritable number:values){
sum += number.get();
}
context.write(key,new IntWritable(sum));
}
}
Original: https://www.cnblogs.com/komorebiZjh/p/16247133.html
Author: 搁浅的小鲸鱼
Title: mapreduce统计单词个数
原创文章受到原创版权保护。转载请注明出处：https://www.johngo689.com/599216/
转载文章受原作者版权保护。转载请注明原作者出处！