org.apache.cayenne.ObjectId Maven / Gradle / Ivy
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.cayenne;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.cayenne.util.EqualsBuilder;
import org.apache.cayenne.util.HashCodeBuilder;
import org.apache.cayenne.util.IDUtil;
import org.apache.cayenne.util.Util;
/**
* A portable global identifier for persistent objects. ObjectId can be temporary (used
* for transient or new uncommitted objects) or permanent (used for objects that have been
* already stored in DB). A temporary ObjectId stores object entity name and a
* pseudo-unique binary key; permanent id stores a map of values from an external
* persistent store (aka "primary key").
*
*/
public class ObjectId implements Serializable {
protected String entityName;
protected Map objectIdKeys;
private String singleKey;
private Object singleValue;
// key which is used for temporary ObjectIds only
protected byte[] key;
protected Map replacementIdMap;
// hash code is transient to make sure id is portable across VM
transient int hashCode;
// exists for deserialization with Hessian and similar
@SuppressWarnings("unused")
private ObjectId() {
}
/**
* Creates a TEMPORARY ObjectId. Assigns a generated unique key.
*
* @since 1.2
*/
public ObjectId(String entityName) {
this(entityName, IDUtil.pseudoUniqueByteSequence8());
}
/**
* Creates a TEMPORARY id with a specified entity name and a binary key. It is a
* caller responsibility to provide a globally unique binary key.
*
* @since 1.2
*/
public ObjectId(String entityName, byte[] key) {
this.entityName = entityName;
this.key = key;
}
/**
* Creates a portable permanent ObjectId.
*
* @param entityName The entity name which this object id is for
* @param key A key describing this object id, usually the attribute name for the
* primary key
* @param value The unique value for this object id
* @since 1.2
*/
public ObjectId(String entityName, String key, int value) {
this(entityName, key, Integer.valueOf(value));
}
/**
* Creates a portable permanent ObjectId.
*
* @param entityName The entity name which this object id is for
* @param key A key describing this object id, usually the attribute name for the
* primary key
* @param value The unique value for this object id
* @since 1.2
*/
public ObjectId(String entityName, String key, Object value) {
this.entityName = entityName;
this.singleKey = key;
this.singleValue = value;
}
/**
* Creates a portable permanent ObjectId as a compound primary key.
*
* @param entityName The entity name which this object id is for
* @param idMap Keys are usually the attribute names for each part of the primary key.
* Values are unique when taken as a whole.
* @since 1.2
*/
public ObjectId(String entityName, Map idMap) {
this.entityName = entityName;
if (idMap == null || idMap.size() == 0) {
}
else if (idMap.size() == 1) {
Map.Entry e = idMap.entrySet().iterator().next();
this.singleKey = String.valueOf(e.getKey());
this.singleValue = e.getValue();
}
else {
// we have to create a copy of the map, otherwise we may run into
// serialization
// problems with hessian
this.objectIdKeys = new HashMap(idMap);
}
}
/**
* Is this is temporary object id (used for objects which are not yet persisted to the
* data store).
*/
public boolean isTemporary() {
return key != null;
}
/**
* @since 1.2
*/
public String getEntityName() {
return entityName;
}
/**
* Get the binary temporary object id. Null if this object id is permanent (persisted
* to the data store).
*/
public byte[] getKey() {
return key;
}
/**
* Returns an unmodifiable Map of persistent id values, essentially a primary key map.
* For temporary id returns replacement id, if it was already created. Otherwise
* returns an empty map.
*/
public Map getIdSnapshot() {
if (isTemporary()) {
return (replacementIdMap == null) ? Collections.EMPTY_MAP : Collections
.unmodifiableMap(replacementIdMap);
}
if (singleKey != null) {
return Collections.singletonMap(singleKey, singleValue);
}
return objectIdKeys != null
? Collections.unmodifiableMap(objectIdKeys)
: Collections.EMPTY_MAP;
}
@Override
public boolean equals(Object object) {
if (this == object) {
return true;
}
if (!(object instanceof ObjectId)) {
return false;
}
ObjectId id = (ObjectId) object;
if (!Util.nullSafeEquals(entityName, id.entityName)) {
return false;
}
if (isTemporary()) {
return new EqualsBuilder().append(key, id.key).isEquals();
}
if (singleKey != null) {
return Util.nullSafeEquals(singleKey, id.singleKey)
&& valueEquals(singleValue, id.singleValue);
}
if (id.objectIdKeys == null) {
return objectIdKeys == null;
}
if (id.objectIdKeys.size() != objectIdKeys.size()) {
return false;
}
for (Map.Entry entry : objectIdKeys.entrySet()) {
Object entryKey = entry.getKey();
Object entryValue = entry.getValue();
if (entryValue == null) {
if (id.objectIdKeys.get(entryKey) != null
|| !id.objectIdKeys.containsKey(entryKey)) {
return false;
}
}
else {
if (!valueEquals(entryValue, id.objectIdKeys.get(entryKey))) {
return false;
}
}
}
return true;
}
private final boolean valueEquals(Object o1, Object o2) {
if (o1 == o2) {
return true;
}
if (o1 == null) {
return false;
}
if (o1 instanceof Number) {
return o2 instanceof Number
&& ((Number) o1).longValue() == ((Number) o2).longValue();
}
if (o1.getClass().isArray()) {
return new EqualsBuilder().append(o1, o2).isEquals();
}
return Util.nullSafeEquals(o1, o2);
}
@Override
public int hashCode() {
if (this.hashCode == 0) {
HashCodeBuilder builder = new HashCodeBuilder(3, 5);
builder.append(entityName.hashCode());
if (key != null) {
builder.append(key);
}
else if (singleKey != null) {
builder.append(singleKey.hashCode());
// must reconcile all possible numeric types
if (singleValue instanceof Number) {
builder.append(((Number) singleValue).longValue());
}
else {
builder.append(singleValue);
}
}
else if (objectIdKeys != null) {
int len = objectIdKeys.size();
// handle multiple keys - must sort the keys to use with HashCodeBuilder
Object[] keys = objectIdKeys.keySet().toArray();
Arrays.sort(keys);
for (int i = 0; i < len; i++) {
// HashCodeBuilder will take care of processing object if it
// happens to be a primitive array such as byte[]
// also we don't have to append the key hashcode, its index will
// work
builder.append(i);
Object value = objectIdKeys.get(keys[i]);
// must reconcile all possible numeric types
if (value instanceof Number) {
builder.append(((Number) value).longValue());
}
else {
builder.append(value);
}
}
}
this.hashCode = builder.toHashCode();
assert hashCode != 0 : "Generated zero hashCode";
}
return hashCode;
}
/**
* Returns a non-null mutable map that can be used to append replacement id values.
* This allows to incrementally build a replacement GlobalID.
*
* @since 1.2
*/
public Map getReplacementIdMap() {
if (replacementIdMap == null) {
replacementIdMap = new HashMap();
}
return replacementIdMap;
}
/**
* Creates and returns a replacement ObjectId. No validation of ID is done.
*
* @since 1.2
*/
public ObjectId createReplacementId() {
// merge existing and replaced ids to handle a replaced subset of
// a compound primary key
Map newIdMap = new HashMap(getIdSnapshot());
if (replacementIdMap != null) {
newIdMap.putAll(replacementIdMap);
}
return new ObjectId(getEntityName(), newIdMap);
}
/**
* Returns true if there is full or partial replacement id attached to this id. This
* method is preferrable to "!getReplacementIdMap().isEmpty()" as it avoids unneeded
* replacement id map creation.
*/
public boolean isReplacementIdAttached() {
return replacementIdMap != null && !replacementIdMap.isEmpty();
}
/**
* A standard toString method used for debugging. It is guaranteed to produce the same
* string if two ObjectIds are equal.
*/
@Override
public String toString() {
StringBuilder buffer = new StringBuilder();
buffer.append("");
return buffer.toString();
}
}
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