hadoop 自定义inputformat和outputformat

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hadoop的inputformat和outputformat

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最好的例子vertica ：虽然是在pig中实现的udf，但是就是hadoop的inputformat和outputformat，在hive里也可以照用，贴个下载的地址：http://blackproof.iteye.com/blog/1791995

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再贴一个项目中，在实现hadoop join时，用的inputformat和outputformat的简单实例：

hadoop join在http://blackproof.iteye.com/blog/1757530

? ?自定义inputformat（泛型是maper的input）

public class MyOutputFormat extends FileOutputFormat<Text, Employee> {@Overridepublic RecordWriter<Text, Employee> getRecordWriter(TaskAttemptContext job) throws IOException, InterruptedException {// TODO Auto-generated method stubConfiguration conf = job.getConfiguration();Path file = getDefaultWorkFile(job, "");FileSystem fs = file.getFileSystem(conf);FSDataOutputStream fileOut = fs.create(file, false);return new MyRecordWriter(fileOut);}public static class MyRecordWriter extends RecordWriter<Text, Employee>{protected DataOutputStream out;private final byte[] keyValueSeparator; public static final String NEW_LINE = System.getProperty("line.separator");public MyRecordWriter(DataOutputStream out){this(out,":");}public MyRecordWriter(DataOutputStream out,String keyValueSeparator){this.out = out;this.keyValueSeparator = keyValueSeparator.getBytes();}@Overridepublic void write(Text key, Employee value) throws IOException,InterruptedException {if(key!=null){out.write(key.toString().getBytes());out.write(keyValueSeparator);}out.write(value.toString().getBytes());out.write(NEW_LINE.getBytes());}@Overridepublic void close(TaskAttemptContext context) throws IOException,InterruptedException {out.close();}}}

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