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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;
import java.io.IOException;
/**
* FileName: DdfferentData
* Author: hadoop
* Email: [email protected]
* Date: 18-10-6 上午9:34
* Description:
* hadoop过滤出不同的数据
*/
public class DdfferentData {
/**
* 使用Mapper将数据文件中的数据本身作为Mapper输出的key直接输出
*/
public static class forDifferenceMapper extends Mapper<Object, Text, Text, Text> {
private final IntWritable one = new IntWritable(1);
private Text mapperValue = new Text(); //存放key的值
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
context.write(value,mapperValue);
}
}
/**
* 使用Reducer将输入的key本身作为key直接输出
*/
public static class forDifferenceReducer extends Reducer<Text, Text, Text, Text> {
private Text reduceValue = new Text();
@Override
protected void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
context.write(key,reduceValue);
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration(); //设置MapReduce的配置
String[] otherArgs = new GenericOptionsParser(conf,args).getRemainingArgs();
if(otherArgs.length < 2){
System.out.println("Usage: DeferentData <in> [<in>...] <out>");
System.exit(2);
}
//Job job = new Job(conf);
Job job = Job.getInstance(conf);
job.setJarByClass(DdfferentData.class);
job.setJobName("DeferentData");
job.setMapperClass(forDifferenceMapper.class);
job.setCombinerClass(forDifferenceReducer.class);//加速MapReduce并行效率
job.setReducerClass(forDifferenceReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
for (int i = 0; i < otherArgs.length-1;++i){
FileInputFormat.addInputPath(job,new Path(otherArgs[i]));
}
FileOutputFormat.setOutputPath(job, new Path(otherArgs[otherArgs.length-1]));
System.exit(job.waitForCompletion(true)?0:1);
}
}