http://github.com/FasterXML/jackson: General data-binding functionality for Jackson: works on core streaming API (FasterXML)
  • Tatu Saloranta
  • Christopher Currie
  • Paul Brown 
package com.fasterxml.jackson.databind;

import java.io.IOException;


Abstract class that defines API used for deserializing JSON content
field names into Java Map keys. These deserializers are only used
if the Map key class is not String or Object.

/**
 * Abstract class that defines API used for deserializing JSON content
 * field names into Java Map keys. These deserializers are only used
 * if the Map key class is not <code>String</code> or <code>Object</code>.
 */
public abstract class KeyDeserializer
{
    
Method called to deserialize a Map key from JSON property name. 
/**
     * Method called to deserialize a {@link java.util.Map} key from JSON property name.
     */
    public abstract Object deserializeKey(String key, DeserializationContext ctxt)
        throws IOException;

    
This marker class is only to be used with annotations, to
indicate that no deserializer is configured.

 Specifically, this class is to be used as the marker for annotation JsonDeserialize. 
/**
     * This marker class is only to be used with annotations, to
     * indicate that <b>no deserializer is configured</b>.
     *<p>
     * Specifically, this class is to be used as the marker for
     * annotation {@link com.fasterxml.jackson.databind.annotation.JsonDeserialize}.
     */
    public abstract static class None
        extends KeyDeserializer { }
}