com.fasterxml.jackson.annotation.ObjectIdGenerator Maven / Gradle / Ivy
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 Type of Object Identifiers produced.
*/
@SuppressWarnings("serial")
public abstract class ObjectIdGenerator
implements java.io.Serializable
{
/*
/**********************************************************
/* 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);
/**
* Accessor that needs to be overridden to return true
* if the Object Id may be serialized as JSON Object; used by, for example,
* JSOG handling.
* The reason accessor is needed is because handling such Object Ids is
* more complex and may incur additional buffering or performance overhead,
* avoiding of which makes sense for common case of scalar object ids
* (or native object ids some formats support).
*
* Default implementation returns false, so needs to be overridden
* by Object-producing generators.
*
* @since 2.5
*/
public boolean maySerializeAsObject() {
return false;
}
/**
* Accessor that may be called (after verifying (via {@link #maySerializeAsObject()})
* whether given name
*
* @param name Name of property to check
* @param parser Parser that points to property name, in case generator needs
* further verification (note: untyped, because JsonParser is defined
* in `jackson-core`, and this package does not depend on it).
*
* @since 2.5
*/
public boolean isValidReferencePropertyName(String name, Object parser) {
return false;
}
/*
/**********************************************************
/* Factory methods
/**********************************************************
*/
/**
* Factory method to create a blueprint instance for specified
* scope. Generators that do not use scope may return 'this'.
*/
public abstract ObjectIdGenerator 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).
*
* Note that actual type of 'context' is
* com.fasterxml.jackson.databind.SerializerProvider,
* 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
* com.fasterxml.jackson.databind.SerializerProvider;
* may be needed by more complex generators to access contextual
* information such as configuration.
*/
public abstract ObjectIdGenerator 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
implements java.io.Serializable
{
private static final long serialVersionUID = 1L;
/**
* Type of {@link ObjectIdGenerator} used for generating Object Id
*/
public final Class type;
/**
* Scope of the Object Id (may be null, to denote global)
*/
public final Class scope;
/**
* Object for which Object Id was generated: can NOT be null.
*/
public final Object key;
/**
* Hash code
*/
private final int hashCode;
public IdKey(Class type, Class scope, Object key) {
if (key == null) {
throw new IllegalArgumentException("Can not construct IdKey for null 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);
}
@Override
public String toString() {
return String.format("[ObjectId: key=%s, type=%s, scope=%s]", key,
(type == null) ? "NONE" : type.getName(),
(scope == null) ? "NONE" : scope.getName());
}
}
}