//$Id: IdentifierValue.java 7017 2005-06-05 04:31:34Z oneovthafew $
package org.hibernate.engine;
import java.io.Serializable;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* A strategy for determining if an identifier value is an identifier of
* a new transient instance or a previously persistent transient instance.
* The strategy is determined by the <tt>unsaved-value</tt> attribute in
* the mapping file.
*
* @author Gavin King
*/
public class IdentifierValue {
private static final Log log = LogFactory.getLog(IdentifierValue.class);
private final Serializable value;
/**
* Always assume the transient instance is newly instantiated
*/
public static final IdentifierValue ANY = new IdentifierValue() {
public final Boolean isUnsaved(Serializable id) {
log.trace("id unsaved-value strategy ANY");
return Boolean.TRUE;
}
public Serializable getDefaultValue(Serializable currentValue) {
return currentValue;
}
public String toString() {
return "SAVE_ANY";
}
};
/**
* Never assume the transient instance is newly instantiated
*/
public static final IdentifierValue NONE = new IdentifierValue() {
public final Boolean isUnsaved(Serializable id) {
log.trace("id unsaved-value strategy NONE");
return Boolean.FALSE;
}
public Serializable getDefaultValue(Serializable currentValue) {
return currentValue;
}
public String toString() {
return "SAVE_NONE";
}
};
/**
* Assume the transient instance is newly instantiated if the identifier
* is null.
*/
public static final IdentifierValue NULL = new IdentifierValue() {
public final Boolean isUnsaved(Serializable id) {
log.trace("id unsaved-value strategy NULL");
return id==null ? Boolean.TRUE : Boolean.FALSE;
}
public Serializable getDefaultValue(Serializable currentValue) {
return null;
}
public String toString() {
return "SAVE_NULL";
}
};
/**
* Assume nothing.
*/
public static final IdentifierValue UNDEFINED = new IdentifierValue() {
public final Boolean isUnsaved(Serializable id) {
log.trace("id unsaved-value strategy UNDEFINED");
return null;
}
public Serializable getDefaultValue(Serializable currentValue) {
return null;
}
public String toString() {
return "UNDEFINED";
}
};
protected IdentifierValue() {
this.value = null;
}
/**
* Assume the transient instance is newly instantiated if
* its identifier is null or equal to <tt>value</tt>
*/
public IdentifierValue(Serializable value) {
this.value = value;
}
/**
* Does the given identifier belong to a new instance?
*/
public Boolean isUnsaved(Serializable id) {
if ( log.isTraceEnabled() ) log.trace("id unsaved-value: " + value);
return id==null || id.equals(value) ? Boolean.TRUE : Boolean.FALSE;
}
public Serializable getDefaultValue(Serializable currentValue) {
return value;
}
public String toString() {
return "identifier unsaved-value: " + value;
}
}
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