|NO.Z.00045|——————————|BigDataEnd|——|Hadoop&MapReduce.V18|——|Hadoop.v18|InputFormat机制|自定义outputFormat|
一、[InputFormat机制之自定义outputFormat]：OutputFormat
### --- OutputFormat
~~~ OutputFormat:是MapReduce输出数据的基类，
~~~ 所有MapReduce的数据输出都实现了OutputFormat抽象类。
~~~ 下面我们介绍几种常见的OutputFormat子类
### --- TextOutputFormat
~~~ 默认的输出格式是TextOutputFormat，它把每条记录写为文本行。
~~~ 它的键和值可以是任意类型，因为TextOutputFormat调用toString()方 法把它们转换为字符串。
### --- SequenceFileOutputFormat
~~~ 将SequenceFileOutputFormat输出作为后续MapReduce任务的输入，
~~~ 这是一种好的输出格式，因为它的格式紧凑，很容易被压缩。二、自定义OutputFormat
### --- 需求分析
~~~ 要在一个MapReduce程序中根据数据的不同输出两类结果到不同目录，
~~~ 这类输出需求可以通过自定义OutputFormat来实现。三、实现步骤
### --- 实现步骤
~~~ 自定义一个类继承FileOutputFormat。
~~~ 改写RecordWriter，改写输出数据的方法write()。### --- 需求
~~~ 网络请求日志数据
http://www.baidu.com
http://www.google.com
http://cn.bing.com
http://www.yanqi.com
http://www.sohu.com
http://www.sina.com
http://www.sin2a.com
http://www.sin2desa.com
http://www.sindsafa.com~~~ # 输出结果
yanqi.log
http://www.yanqi.com### --- other.log
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四、编程实现
### --- 创建项目：output
~~~ Mapper
package com.yanqi.mr.output;
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 OutputMapper 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.yanqi.mr.output;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;
import java.io.IOException;
public class OutputReducer extends Reducer<Text, NullWritable, Text, NullWritable> {
@Override
protected void reduce(Text key, Iterable<NullWritable> values, Context context) throws IOException, InterruptedException {
context.write(key, NullWritable.get());
}
}### --- OutputFormat
package com.yanqi.mr.output;
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;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import java.io.IOException;
public class CustomOutputFormat extends FileOutputFormat<Text, NullWritable> {
//写出数据的对象
@Override
public RecordWriter<Text, NullWritable> getRecordWriter(TaskAttemptContext context) throws IOException, InterruptedException {
//定义写出数据的路径信息，并获取到输出流传入writer对象中
final Configuration conf = context.getConfiguration();
final FileSystem fs = FileSystem.get(conf);
//定义输出的路径
final FSDataOutputStream yanqiOut = fs.create(new Path("e:/yanqi.log"));
final FSDataOutputStream otherOut = fs.create(new Path("e:/other.log"));
CustomWriter customWriter = new CustomWriter(yanqiOut, otherOut);
return customWriter;
}
}### --- RecordWriter
package com.yanqi.mr.output;
import org.apache.hadoop.fs.FSDataOutputStream;
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 CustomWriter extends RecordWriter<Text, NullWritable> {
//定义成员变量
private FSDataOutputStream yanqiOut;
private FSDataOutputStream otherOut;
//定义构造方法接收两个输出流
public CustomWriter(FSDataOutputStream yanqiOut, FSDataOutputStream otherOut) {
this.yanqiOut = yanqiOut;
this.otherOut = otherOut;
}
//写出数据的逻辑,控制写出的路径
@Override
public void write(Text key, NullWritable value) throws IOException, InterruptedException {
//写出数据需要输出流
final String line = key.toString();
if (line.contains("yanqi")) {
yanqiOut.write(line.getBytes());
yanqiOut.write("\r\n".getBytes());
} else {
otherOut.write(line.getBytes());
otherOut.write("\r\n".getBytes());
}
}
//关闭，释放资源
@Override
public void close(TaskAttemptContext context) throws IOException, InterruptedException {
IOUtils.closeStream(yanqiOut);
IOUtils.closeStream(otherOut);
}
}### --- Driver：验证结果是否已把数据分别输出到不同的目录中！！
package com.yanqi.mr.output;
import com.yanqi.mr.wc.WordCountDriver;
import com.yanqi.mr.wc.WordCountMapper;
import com.yanqi.mr.wc.WordCountReducer;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
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.CombineTextInputFormat;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import java.io.IOException;
public class OutputDriver {
public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
/*
1. 获取配置文件对象，获取job对象实例
2. 指定程序jar的本地路径
3. 指定Mapper/Reducer类
4. 指定Mapper输出的kv数据类型
5. 指定最终输出的kv数据类型
6. 指定job处理的原始数据路径
7. 指定job输出结果路径
8. 提交作业
*/
// 1. 获取配置文件对象，获取job对象实例
final Configuration conf = new Configuration();
final Job job = Job.getInstance(conf, "OutputDriver");
// 2. 指定程序jar的本地路径
job.setJarByClass(OutputDriver.class);
// 3. 指定Mapper/Reducer类
job.setMapperClass(OutputMapper.class);
job.setReducerClass(OutputReducer.class);
// 4. 指定Mapper输出的kv数据类型
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(NullWritable.class);
// 5. 指定最终输出的kv数据类型
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(NullWritable.class);
//指定使用自定义outputformat
job.setOutputFormatClass(CustomOutputFormat.class);
FileInputFormat.setInputPaths(job, new Path("E:\\data\\input")); //指定读取数据的原始路径
// 7. 指定job输出结果路径,因为mr默认要输出一个success等标识文件
FileOutputFormat.setOutputPath(job, new Path("E:\\data\\output")); //指定结果数据输出路径
// 8. 提交作业
final boolean flag = job.waitForCompletion(true);
//jvm退出：正常退出0，非0值则是错误退出
System.exit(flag ? 0 : 1);
}
}五、编译打印
### --- 编译打印
~~~ 配置输出输出参数
~~~ 定义输入输出参数文件地址
~~~ 编译打印
Walter Savage Landor:strove with none,for none was worth my strife.Nature I loved and, next to Nature, Art:I warm’d both hands before the fire of life.It sinks, and I am ready to depart
——W.S.Landor
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