package com.fasterxml.jackson.annotation;
/**
* Definition of API used for constructing Object Identifiers
* (as annotated using {@link JsonIdentityInfo}).
* Also defines factory methods used for creating instances
* for serialization, deserialization.
*
* @param <T> Type of Object Identifiers produced.
*/
public abstract class ObjectIdGenerator<T>
{
/*
/**********************************************************
/* Accessors
/**********************************************************
*/
public abstract Class<?> getScope();
/**
* Method called to check whether this generator instance can
* be used for Object Ids of specific generator type and
* scope; determination is based by passing a configured
* "blueprint" (prototype) instance; from which the actual
* instances are created (using {@link #newForSerialization}).
*
* @return True if this instance can be used as-is; false if not
*/
public abstract boolean canUseFor(ObjectIdGenerator<?> gen);
/*
/**********************************************************
/* Factory methods
/**********************************************************
*/
/**
* Factory method to create a blueprint instance for specified
* scope. Generators that do not use scope may return 'this'.
*/
public abstract ObjectIdGenerator<T> forScope(Class<?> scope);
/**
* Factory method called to create a new instance to use for
* serialization: needed since generators may have state
* (next id to produce).
*<p>
* Note that actual type of 'context' is
* <code>com.fasterxml.jackson.databind.SerializerProvider</code>,
* but can not be declared here as type itself (as well as call
* to this object) comes from databind package.
*
* @param context Serialization context object used (of type
* <code>com.fasterxml.jackson.databind.SerializerProvider</code>;
* may be needed by more complex generators to access contextual
* information such as configuration.
*/
public abstract ObjectIdGenerator<T> newForSerialization(Object context);
/**
* Method for constructing key to use for ObjectId-to-POJO maps.
*/
public abstract IdKey key(Object key);
/*
/**********************************************************
/* Methods for serialization
/**********************************************************
*/
/**
* Method used for generating a new Object Identifier to serialize
* for given POJO.
*
* @param forPojo POJO for which identifier is needed
*
* @return Object Identifier to use.
*/
public abstract T generateId(Object forPojo);
/*
/**********************************************************
/* Helper classes
/**********************************************************
*/
/**
* Simple key class that can be used as a key for
* ObjectId-to-POJO mappings, when multiple ObjectId types
* and scopes are used.
*/
public final static class IdKey
{
/**
* Type of {@link ObjectIdGenerator} used for generating Object Id
*/
private final Class<?> type;
/**
* Scope of the Object Id (may be null, to denote global)
*/
private final Class<?> scope;
/**
* Object for which Object Id was generated: can NOT be null.
*/
private final Object key;
/**
* Hash code
*/
private final int hashCode;
public IdKey(Class<?> type, Class<?> scope, Object key) {
this.type = type;
this.scope = scope;
this.key = key;
int h = key.hashCode() + type.getName().hashCode();
if (scope != null) {
h ^= scope.getName().hashCode();
}
hashCode = h;
}
@Override
public int hashCode() { return hashCode; }
@Override
public boolean equals(Object o)
{
if (o == this) return true;
if (o == null) return false;
if (o.getClass() != getClass()) return false;
IdKey other = (IdKey) o;
return (other.key.equals(key)) && (other.type == type) && (other.scope == scope);
}
}
}