hadoop案例：自定义outputformat

心已赠人 2022-11-21 15:14 184阅读 0赞

### 文章目录 ###

*   *  需求
     *  输入数据
     *  期望输出数据
     *  需求分析
     *  编写代码
     *   *  自定义FilterOutputFormat
         *  自定义FilterRecordWriter
         *  Mapper类
         *  Reducer类
         *  Driver类
         *  执行结果

## 需求 ##

过滤输入的log日志，包含hadoop的网站输出到e:/hadoop.log，不包含hadoop的网站输出到e:/other.log

## 输入数据 ##

log.txt

http://www.baidu.com
    http://www.google.com
    http://cn.bing.com
    http://www.hadoop.com
    http://www.sohu.com
    http://www.sina.com
    http://www.sin2a.com
    http://www.sin2desa.com
    http://www.sindsafa.com

## 期望输出数据 ##

![在这里插入图片描述][20201102153305394.png_pic_center]

## 需求分析 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjc0MzYw_size_16_color_FFFFFF_t_70_pic_center]

## 编写代码 ##

### 自定义FilterOutputFormat ###

package com.mr.filteroutformat;
    
    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 FilterOutputFormat extends FileOutputFormat<Text, NullWritable> { 
        @Override
        public RecordWriter<Text, NullWritable> getRecordWriter(TaskAttemptContext job) throws IOException, InterruptedException { 
    
    
    
            return new FilterRecordWriter(job);
        }
    }

### 自定义FilterRecordWriter ###

package com.mr.filteroutformat;
    
    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 FilterRecordWriter extends RecordWriter<Text, NullWritable> { 
    
    
        //构造器方法
        FSDataOutputStream hadoopOut = null;
        FSDataOutputStream otherOut = null;
    
    
        public FilterRecordWriter(TaskAttemptContext job) { 
            FileSystem fs;
            try { 
                fs = FileSystem.get(job.getConfiguration());
    
                // 2 创建输出文件路径
                Path hadoopPath = new Path("E:\\Hadoop\\src\\main\\resources\\ouput\\filterlog\\hadoop.log");
                Path otherPath = new Path("E:\\Hadoop\\src\\main\\resources\\ouput\\filterlog\\.other.log");
    
                // 3 创建输出流
                hadoopOut = fs.create(hadoopPath);
                otherOut = fs.create(otherPath);
            } catch (IOException e) { 
                e.printStackTrace();
            }
    
    
        }
    
        @Override
        public void write(Text key, NullWritable value) throws IOException, InterruptedException { 
    // 判断是否包含“hadoop”输出到不同文件
            if (key.toString().contains("hadoop")) { 
                hadoopOut.write(key.toString().getBytes());
            } else { 
                otherOut.write(key.toString().getBytes());
            }
    
        }
    
        @Override
        public void close(TaskAttemptContext taskAttemptContext) throws IOException, InterruptedException { 
    // 关闭资源
            IOUtils.closeStream(hadoopOut);
            IOUtils.closeStream(otherOut);
    
        }
    }

### Mapper类 ###

package com.mr.filteroutformat;
    
    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 FilterMapper 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类 ###

package com.mr.filteroutformat;
    
    import org.apache.hadoop.io.NullWritable;
    import org.apache.hadoop.io.Text;
    import org.apache.hadoop.mapreduce.Reducer;
    
    import java.io.IOException;
    
    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 获取一行
            String line = key.toString();
    
            // 2 拼接
            line = line + "\r\n";
    
            // 3 设置key
            k.set(line);
    
            // 4 输出
            context.write(k, NullWritable.get());
    
    
        }
    }

### Driver类 ###

package com.mr.filteroutformat;
    
    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 FilterDriver  { 
        public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException { 
    
            // 输入输出路径需要根据自己电脑上实际的输入输出路径设置
            args = new String[] {  "E:\\Hadoop\\src\\main\\resources\\input\\filterlog", "E:\\Hadoop\\src\\main\\resources\\ouput\\filterlog" };
    
            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);
    
            // 要将自定义的输出格式组件设置到job中
            job.setOutputFormatClass(FilterOutputFormat.class);
    
            FileInputFormat.setInputPaths(job, new Path(args[0]));
    
            // 虽然我们自定义了outputformat，但是因为我们的outputformat继承自fileoutputformat
            // 而fileoutputformat要输出一个_SUCCESS文件，所以，在这还得指定一个输出目录
            FileOutputFormat.setOutputPath(job, new Path(args[1]));
    
            boolean result = job.waitForCompletion(true);
            System.exit(result ? 0 : 1);
        }
    
    }

### 执行结果 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjc0MzYw_size_16_color_FFFFFF_t_70_pic_center 1]

[20201102153305394.png_pic_center]: /images/20221120/f4e055dbbeaa486abff6d966bcabcd54.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjc0MzYw_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/d8d49ab0384d462ea653b1e8c833f3b8.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjc0MzYw_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221120/34ac8995a76942659d7d393db61af570.png