使用MapReduce实现输入目录下图片的去重

下面是使用Java语言编写的MapReduce程序，可以将指定目录下的图片进行去重，输出去重后的结果到指定目录下。具体实现过程如下：

// 导入所需的包
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

public class ImageDeduplication {
  public static class Map extends MapReduceBase implements Mapper<text, byteswritable="" byteswritable,="" text,=""> {
    private Text outputKey = new Text();

    public void map(Text key, BytesWritable value, OutputCollector""> output, Reporter reporter) throws IOException {
      // 将图片数据转换为Base64编码
      String imageBase64 = javax.xml.bind.DatatypeConverter.printBase64Binary(value.getBytes());

      // 将图片Base64编码作为key，图片数据作为value输出
      outputKey.set(imageBase64);
      output.collect(outputKey, value);
    }
  }

  public static class Reduce extends MapReduceBase implements Reducer<text, byteswritable="" byteswritable,="" text,=""> {
    public void reduce(Text key, Iterator values, OutputCollector""> output, Reporter reporter) throws IOException {
      // 只输出第一个key对应的图片数据
      output.collect(key, values.next());
    }
  }

  public static void main(String[] args) throws Exception {
    JobConf conf = new JobConf(ImageDeduplication.class);
    conf.setJobName("Image Deduplication");

    // 设置MapReduce的输入输出路径
    FileInputFormat.addInputPath(conf, new Path(args[0]));
    FileOutputFormat.setOutputPath(conf, new Path(args[1]));

    // 设置MapReduce的Mapper和Reducer
    conf.setMapperClass(Map.class);
    conf.setReducerClass(Reduce.class);

    // 设置MapReduce的输出格式
    conf.setOutputKeyClass(Text.class);
    conf.setOutputValueClass(BytesWritable.class);

    JobClient.runJob(conf);
  }
}
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