简介

可以自定义输出的格式和文件，例如包含某字段的输出到一个指定文件，不包含某字段的输出到另一个文件。

案例

数据

www.nevesettle.com

www.baidu.com

www.qq.com

www.mi.com

www.jd.com

www.std.com

Mapper

package com.neve.outputformat;

import org.apache.hadoop.io.LongWritable;

import org.apache.hadoop.io.NullWritable;

import org.apache.hadoop.io.Text;

import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;

public class LogMapper extends Mapper<LongWritable, Text,Text, NullWritable> {

    @Override

    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

        context.write(value,NullWritable.get());

    }

}

Reducer

package com.neve.outputformat;

import org.apache.hadoop.io.NullWritable;

import org.apache.hadoop.io.Text;

import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class LogReducer extends Reducer<Text, NullWritable,Text,NullWritable> {

    @Override

    protected void reduce(Text key, Iterable<NullWritable> values, Context context) throws IOException, InterruptedException {

        for (NullWritable value : values) {

            context.write(key,value);

        }

    }

}

Driver

package com.neve.outputformat;

import com.neve.phone.FlowBean;

import com.neve.phone.FlowMapper;

import com.neve.phone.FlowReducer;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.fs.Path;

import org.apache.hadoop.io.NullWritable;

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;

import java.io.IOException;

public class LogDriver {

    public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {

        //1.创建配置

        Configuration configuration = new Configuration();

        //2.创建job

        Job job = Job.getInstance(configuration);

        //3.关联驱动类

        job.setJarByClass(LogDriver.class);

        //4.关联mapper和reducer类

        job.setMapperClass(LogMapper.class);

        job.setReducerClass(LogReducer.class);

        //5.设置mapper的输出值和value

        job.setMapOutputKeyClass(Text.class);

        job.setMapOutputValueClass(NullWritable.class);

        //6.设置最终的输出值和value

        job.setOutputKeyClass(Text.class);

        job.setOutputValueClass(NullWritable.class);

        //7.设置输入输出路径

        FileInputFormat.setInputPaths(job,new Path("F:\\Workplace\\IDEA_Workplace\\hadoopStudy2\\outputformatinput"));

        FileOutputFormat.setOutputPath(job,new Path("F:\\Workplace\\IDEA_Workplace\\hadoopStudy2\\outputformatoutput"));

        //设置自定义的format类

        job.setOutputFormatClass(LogOutputFormat.class);

        //8.提交job

        job.waitForCompletion(true);

    }

}

LogOutputFormat

package com.neve.outputformat;

import org.apache.hadoop.io.NullWritable;

import org.apache.hadoop.io.Text;

import org.apache.hadoop.mapreduce.RecordWriter;

import org.apache.hadoop.mapreduce.TaskAttemptContext;

import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

public class LogOutputFormat extends FileOutputFormat<Text, NullWritable> {

    public RecordWriter<Text, NullWritable> getRecordWriter(TaskAttemptContext job) throws IOException, InterruptedException {

        LogRecordWriter logw = new LogRecordWriter(job);

        return logw;

    }

}

LogRecordWriter

package com.neve.outputformat;

import org.apache.hadoop.fs.FSDataOutputStream;

import org.apache.hadoop.fs.FileSystem;

import org.apache.hadoop.fs.Path;

import org.apache.hadoop.io.IOUtils;

import org.apache.hadoop.io.NullWritable;

import org.apache.hadoop.io.Text;

import org.apache.hadoop.mapreduce.RecordWriter;

import org.apache.hadoop.mapreduce.TaskAttemptContext;

import java.io.IOException;

public class LogRecordWriter extends RecordWriter<Text, NullWritable> {

    //定义输出路径

    private String nelog = "F:\\nelog.log";

    private String otherlog = "F:\\otherlog.log";

    private FileSystem fs ;

    private FSDataOutputStream neos;

    private FSDataOutputStream otheros;

    public LogRecordWriter(TaskAttemptContext job) throws IOException {

        //获取文件系统对象

        fs = FileSystem.get(job.getConfiguration());

        neos = fs.create(new Path(nelog));

        otheros = fs.create(new Path(otherlog));

    }

    public void write(Text key, NullWritable value) throws IOException, InterruptedException {

        String string = key.toString();

        if (string.contains("neve")){

            neos.writeBytes(string + "\r");

        }else {

            otheros.writeBytes(string + "\r");

        }

    }

    public void close(TaskAttemptContext context) throws IOException, InterruptedException {

        IOUtils.closeStream(neos);

        IOUtils.closeStream(otheros);

    }

}

巴特西

OutputFormat---自定义输出方式

简介

案例

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