过滤日志及自定义日志输出路径（自定义OutputFormat）

1）需求
过滤输入的log日志中是否包含atguigu
（1）包含atguigu的网站输出到e:/atguigu.log
（2）不包含atguigu的网站输出到e:/other.log

2）输入数据
log.txt:

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

atguigu.txt:

http://www.atguigu.com

other.txt

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

3）具体程序：
（1）自定义一个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 {
		
		// 创建一个RecordWriter
		return new FilterRecordWriter(job);
	}
}

（2）具体的写数据RecordWriter

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
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>{
	private FSDataOutputStream atguiguOut = null;
	private FSDataOutputStream otherOut = null;
	
	public FilterRecordWriter(TaskAttemptContext job)  {
		Configuration configuration = job.getConfiguration();
		
		try {
			// 获取文件系统
			FileSystem fs = FileSystem.get(configuration);
			
			// 创建两个文件的输出流
			atguiguOut = fs.create(new Path("e:/output/atguigu.log"));
			
			otherOut = fs.create(new Path("e:/output/other.log"));
		} catch (IOException e) {
			
			e.printStackTrace();
		}
	}

	@Override
	public void write(Text key, NullWritable value) throws IOException, InterruptedException {
		// 区分输入的key是否包含atguigu
		
		if (key.toString().contains("atguigu")) {// 包含
			atguiguOut.write(key.toString().getBytes());
		}else {// 不包含
			otherOut.write(key.toString().getBytes());
		}
	}

	@Override
	public void close(TaskAttemptContext context) throws IOException, InterruptedException {	
		if (atguiguOut != null) {
			atguiguOut.close();
		}
		
		if (otherOut != null) {
			otherOut.close();
		}
	}
}

（3）编写FilterMapper

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>{
	private Text k = new Text();
	
	@Override
	protected void map(LongWritable key, Text value, Context context)
			throws IOException, InterruptedException {
		
		// 获取一行
		String line = value.toString();
		
		k.set(line);
		
		// 写出
		context.write(k, NullWritable.get());
	}
}

（4）编写FilterReducer

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 {
		
		// 在key上加上回车和换行符
		k.set(key.toString() + "\r\n");
		
		context.write(k, NullWritable.get());
	}
}

（5）编写FilterDriver

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 {
		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);
	}
}