1 OutputFormat介面實現類

2自定義OutputFormat

3 自定義OutputFormat案例實操

1．需求

過濾輸入的log日誌，包含atguigu的網站輸出到e:/atguigu.log，不包含atguigu的網站輸出到e:/other.log。

（1）輸入資料

（2）期望輸出資料

2．需求分析

3．案例實操

（1）編寫FilterMapper類

package com.atguigu.mapreduce.outputformat;
import java.io.IOException;
import org.apache.hadoop.io.LongWritable;
 
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

public class FilterMapper extends Mapper<LongWritable, Text, Text, NullWritable>{
    
    @Override
    protected void map(LongWritable key, Text value, Context context)    throws
 
 IOException, InterruptedException {

        // 寫出
        context.write(value, NullWritable.get());
    }
}

（2）編寫FilterReducer類

package com.atguigu.mapreduce.outputformat;
import java.io.IOException;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

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

Text k = new Text();

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

       // 1 獲取一行
        String line = key.toString();

       // 2 拼接
        line = line + "\r\n";

       // 3 設定key
       k.set(line);

       // 4 輸出
        context.write(k, NullWritable.get());
    }
}

（3）自定義一個OutputFormat類

package com.atguigu.mapreduce.outputformat;
import java.io.IOException;
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;

public class FilterOutputFormat extends FileOutputFormat<Text, NullWritable>{

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

        // 建立一個RecordWriter
        return new FilterRecordWriter(job);
    }
}

（4）編寫RecordWriter類

package com.atguigu.mapreduce.outputformat;
import java.io.IOException;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

public class FilterRecordWriter extends RecordWriter<Text, NullWritable> {

    FSDataOutputStream atguiguOut = null;
    FSDataOutputStream otherOut = null;

    public FilterRecordWriter(TaskAttemptContext job) {

        // 1 獲取檔案系統
        FileSystem fs;

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

            // 2 建立輸出檔案路徑
            Path atguiguPath = new Path("e:/atguigu.log");
            Path otherPath = new Path("e:/other.log");

            // 3 建立輸出流
            atguiguOut = fs.create(atguiguPath);
            otherOut = fs.create(otherPath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

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

        // 判斷是否包含“atguigu”輸出到不同檔案
        if (key.toString().contains("atguigu")) {
            atguiguOut.write(key.toString().getBytes());
        } else {
            otherOut.write(key.toString().getBytes());
        }
    }

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

        // 關閉資源
IOUtils.closeStream(atguiguOut);
        IOUtils.closeStream(otherOut);    }
}

（5）編寫FilterDriver類

package com.atguigu.mapreduce.outputformat;
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;

public class FilterDriver {

    public static void main(String[] args) throws Exception {

// 輸入輸出路徑需要根據自己電腦上實際的輸入輸出路徑設定
args = new String[] { "e:/input/inputoutputformat", "e:/output2" };

        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf);

        job.setJarByClass(FilterDriver.class);
        job.setMapperClass(FilterMapper.class);
        job.setReducerClass(FilterReducer.class);

        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(NullWritable.class);
        
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(NullWritable.class);

        // 要將自定義的輸出格式元件設定到job中
        job.setOutputFormatClass(FilterOutputFormat.class);

        FileInputFormat.setInputPaths(job, new Path(args[0]));

        // 雖然我們自定義了outputformat，但是因為我們的outputformat繼承自fileoutputformat
        // 而fileoutputformat要輸出一個_SUCCESS檔案，所以，在這還得指定一個輸出目錄
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        boolean result = job.waitForCompletion(true);
        System.exit(result ? 0 : 1);
    }
}