Package org.apache.hadoop.io

Class AbstractMapWritable

java.lang.Object
org.apache.hadoop.io.AbstractMapWritable
All Implemented Interfaces:
Configurable, Writable
Direct Known Subclasses:
MapWritable, SortedMapWritable
@Public @Stable public abstract class AbstractMapWritable extends Object implements Writable, Configurable
Abstract base class for MapWritable and SortedMapWritable Unlike org.apache.nutch.crawl.MapWritable, this class allows creation of MapWritable<Writable, MapWritable> so the CLASS_TO_ID and ID_TO_CLASS maps travel with the class instead of being static. Class ids range from 1 to 127 so there can be at most 127 distinct classes in any specific map instance.

  • Constructor Details

    • AbstractMapWritable

      protected AbstractMapWritable()
      constructor.

  • Method Details

    • addToMap

      protected void addToMap(Class<?> clazz)
      Add a Class to the maps if it is not already present.
      Parameters:
      clazz - clazz.

    • getClass

      protected Class<?> getClass(byte id)
      the Class class for the specified id.
      Parameters:
      id - id.
      Returns:
      the Class class for the specified id.

    • getId

      protected byte getId(Class<?> clazz)
      get id.
      Parameters:
      clazz - clazz.
      Returns:
      the id for the specified Class.

    • copy

      protected void copy(Writable other)
      Used by child copy constructors.
      Parameters:
      other - other.

    • getConf

      public Configuration getConf()
      Description copied from interface: Configurable
      Return the configuration used by this object.
      Specified by:
      getConf in interface Configurable
      Returns:
      the conf

    • setConf

      public void setConf(Configuration conf)
      Description copied from interface: Configurable
      Set the configuration to be used by this object.
      Specified by:
      setConf in interface Configurable
      Parameters:
      conf - the conf to set

    • write

      public void write(DataOutput out) throws IOException
      Description copied from interface: Writable
      Serialize the fields of this object to out.
      Specified by:
      write in interface Writable
      Parameters:
      out - DataOuput to serialize this object into.
      Throws:
      IOException - any other problem for write.

    • readFields

      public void readFields(DataInput in) throws IOException
      Description copied from interface: Writable
      Deserialize the fields of this object from in.

      For efficiency, implementations should attempt to re-use storage in the existing object where possible.

      Specified by:
      readFields in interface Writable
      Parameters:
      in - DataInput to deseriablize this object from.
      Throws:
      IOException - any other problem for readFields.