自定义outputformat

/**
 * maptask或者reducetask在最终输出时，先调用OutputFormat的getRecordWriter方法拿到一个RecordWriter
 * 然后再调用RecordWriter的write(k,v)方法将数据写出
 * 
 * @author
 * 
 */
public class LogEnhanceOutputFormat extends FileOutputFormat<Text, NullWritable> {


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


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


Path enhancePath = new Path("D:/temp/en/log.dat");
Path tocrawlPath = new Path("D:/temp/crw/url.dat");


FSDataOutputStream enhancedOs = fs.create(enhancePath);
FSDataOutputStream tocrawlOs = fs.create(tocrawlPath);


return new EnhanceRecordWriter(enhancedOs, tocrawlOs);
}


/**
* 构造一个自己的recordwriter
* 
* @author
* 
*/
static class EnhanceRecordWriter extends RecordWriter<Text, NullWritable> {
FSDataOutputStream enhancedOs = null;
FSDataOutputStream tocrawlOs = null;


public EnhanceRecordWriter(FSDataOutputStream enhancedOs, FSDataOutputStream tocrawlOs) {
super();
this.enhancedOs = enhancedOs;
this.tocrawlOs = tocrawlOs;
}


@Override
public void write(Text key, NullWritable value) throws IOException, InterruptedException {
String result = key.toString();
// 如果要写出的数据是待爬的url，则写入待爬清单文件 /logenhance/tocrawl/url.dat
if (result.contains("tocrawl")) {
tocrawlOs.write(result.getBytes());
} else {
// 如果要写出的数据是增强日志，则写入增强日志文件 /logenhance/enhancedlog/log.dat
enhancedOs.write(result.getBytes());
}


}


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


}


}

}

//在客户端注明

// 要控制不同的内容写往不同的目标路径，可以采用自定义outputformat的方法
job.setOutputFormatClass(LogEnhanceOutputFormat.class);


FileInputFormat.setInputPaths(job, new Path("D:/srcdata/webloginput/"));


// 尽管我们用的是自定义outputformat，但是它是继承制fileoutputformat
// 在fileoutputformat中，必须输出一个_success文件，所以在此还需要设置输出path
FileOutputFormat.setOutputPath(job, new Path("D:/temp/output/"));


// 不需要reducer
job.setNumReduceTasks(0);