org.apache.nutch.metadata
Class MetaWrapper

java.lang.Object
  org.apache.hadoop.io.GenericWritable
      org.apache.nutch.util.GenericWritableConfigurable
          org.apache.nutch.crawl.NutchWritable
              org.apache.nutch.metadata.MetaWrapper

All Implemented Interfaces:

Configurable, Writable

public class MetaWrapper
extends NutchWritable

This is a simple decorator that adds metadata to any Writable-s that can be serialized by NutchWritable. This is useful when data needs to be temporarily enriched during processing, but this temporary metadata doesn't need to be permanently stored after the job is done.

Author:

Andrzej Bialecki

Constructor Summary

MetaWrapper()

MetaWrapper(Metadata metadata, Writable instance, Configuration conf)

MetaWrapper(Writable instance, Configuration conf)

Method Summary

void	addMeta(String name, String value) Add metadata.
String	getMeta(String name) Get metadata.
Metadata	getMetadata() Get all metadata.
String[]	getMetaValues(String name) Get multiple metadata.
void	readFields(DataInput in)
void	setMeta(String name, String value) Set metadata.
void	write(DataOutput out)

Methods inherited from class org.apache.nutch.crawl.NutchWritable

getTypes

Methods inherited from class org.apache.nutch.util.GenericWritableConfigurable

getConf, setConf

Methods inherited from class org.apache.hadoop.io.GenericWritable

get, set, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

MetaWrapper

public MetaWrapper()

MetaWrapper

public MetaWrapper(Writable instance,
                   Configuration conf)

MetaWrapper

public MetaWrapper(Metadata metadata,
                   Writable instance,
                   Configuration conf)

Method Detail

getMetadata

public Metadata getMetadata()

Get all metadata.

addMeta

public void addMeta(String name,
                    String value)

Add metadata. See Metadata.add(String, String) for more information.

Parameters:

name - metadata name

value - metadata value

setMeta

public void setMeta(String name,
                    String value)

Set metadata. See Metadata.set(String, String) for more information.

Parameters:

name -

value -

getMeta

public String getMeta(String name)

Get metadata. See Metadata.get(String) for more information.

Parameters:

name -

Returns:

metadata value

getMetaValues

public String[] getMetaValues(String name)

Get multiple metadata. See Metadata.getValues(String) for more information.

Parameters:

name -

Returns:

multiple values

readFields

public void readFields(DataInput in)
                throws IOException

Specified by:

readFields in interface Writable

Overrides:

readFields in class GenericWritableConfigurable

Throws:

IOException

write

public void write(DataOutput out)
           throws IOException

Specified by:

write in interface Writable

Overrides:

write in class GenericWritable

Throws:

IOException