这篇文章主要讲解了“Hadoop怎么实现数据去重”,文中的讲解内容简单清晰,易于学习与理解,下面请大家跟着小编的思路慢慢深入,一起来研究和学习“Hadoop怎么实现数据去重”吧!
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;
import org.apache.hadoop.util.GenericOptionsParser;
public class QuChong {
/**
* 数据去重 利用并化的的思想
* @author hadoop
*
*/
public static class Engine extends Mapper<Object, Text, Text, Text>{
public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
String line = value.toString();
context.write(new Text(line), new Text(""));
}
}
public static class IntSumReducer extends Reducer<Text,IntWritable,Text,Text> {
public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
context.write(key, new Text(""));
}
}
public static void main(String[] args) throws Exception {
//设置引擎配置类,包括引擎地址,引擎输入输出参数(目录)
Configuration conf = new Configuration();
String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
if (otherArgs.length != 2) {
System.err.println("Usage: wordcount <in> <out>");
System.exit(2);
}
Job job = new Job(conf, "word count");
job.setJarByClass(QuChong.class);
//设置Map、Combine和Reduce处理类
job.setMapperClass(Engine.class);
job.setCombinerClass(IntSumReducer.class);
job.setReducerClass(IntSumReducer.class);
//设置输出类
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
//设置输入类及输入目录
FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
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