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package oracle.toplink.essentials.sequencing;
import java.util.Vector;
import java.math.*;
import oracle.toplink.essentials.internal.sessions.AbstractSession;
import oracle.toplink.essentials.internal.databaseaccess.Accessor;
import oracle.toplink.essentials.exceptions.ValidationException;
import oracle.toplink.essentials.exceptions.DatabaseException;
/**
* <p>
* <b>Purpose</b>: An abstract class providing default sequence behavior.
* <p>
*/
public abstract class StandardSequence extends Sequence {
public StandardSequence() {
super();
}
public StandardSequence(String name) {
super(name);
}
public StandardSequence(String name, int size) {
super(name, size);
}
public StandardSequence(String name, int size, int initialValue) {
super(name, size, initialValue);
}
public void onConnect() {
// does nothing
}
public void onDisconnect() {
// does nothing
}
protected abstract Number updateAndSelectSequence(Accessor accessor, AbstractSession writeSession, String seqName, int size);
public abstract boolean shouldAcquireValueAfterInsert();
public abstract boolean shouldUseTransaction();
public Object getGeneratedValue(Accessor accessor, AbstractSession writeSession, String seqName) {
if (shouldUsePreallocation()) {
return null;
} else {
Number value = updateAndSelectSequence(accessor, writeSession, seqName, 1);
if (value == null) {
throw DatabaseException.errorPreallocatingSequenceNumbers();
}
return value;
}
}
public Vector getGeneratedVector(Accessor accessor, AbstractSession writeSession, String seqName, int size) {
if (shouldUsePreallocation()) {
Number value = updateAndSelectSequence(accessor, writeSession, seqName, size);
if (value == null) {
throw DatabaseException.errorPreallocatingSequenceNumbers();
}
return createVector(value, seqName, size);
} else {
return null;
}
}
/**
* INTERNAL:
* Indicates whether existing attribute value should be overridden.
* This method is called in case an attribute mapped to PK of sequencing-using
* descriptor contains non-null value.
* Default implementation is: Always override for "after insert" sequencing,
* override non-positive Numbers for "before insert" sequencing.
* @param seqName String is sequencing number field name
* @param existingValue Object is a non-null value of PK-mapped attribute.
*/
public boolean shouldOverrideExistingValue(String seqName, Object existingValue) {
if (shouldAcquireValueAfterInsert()) {
return true;
} else {
// Check if the stored number is greater than zero (a valid sequence number)
if (existingValue instanceof BigDecimal) {
if (((BigDecimal)existingValue).signum() <= 0) {
return true;
}
} else if (existingValue instanceof BigInteger) {
if (((BigInteger)existingValue).signum() <= 0) {
return true;
}
}
//CR#2645: Fix for String ClassCastException. Now we don't assume
//anything which is not a BigDecimal to be a Number.
else if (existingValue instanceof Number && (((Number)existingValue).longValue() <= 0)) {
return true;
}
return false;
}
}
/**
* INTERNAL:
* given sequence = 10, size = 5 will create Vector (6,7,8,9,10)
* @param seqName String is sequencing number field name
* @param existingValue Object is a non-null value of PK-mapped attribute.
* @param size int size of Vector to create.
*/
protected Vector createVector(Number sequence, String seqName, int size) {
BigDecimal nextSequence;
BigDecimal increment = new BigDecimal(1);
if (sequence instanceof BigDecimal) {
nextSequence = (BigDecimal)sequence;
} else {
nextSequence = new BigDecimal(sequence.doubleValue());
}
Vector sequencesForName = new Vector(size);
nextSequence = nextSequence.subtract(new BigDecimal(size));
// Check for incorrect values return to validate that the sequence is setup correctly.
// PRS 36451 intvalue would wrap
if (nextSequence.doubleValue() < -1) {
throw ValidationException.sequenceSetupIncorrectly(seqName);
}
for (int index = size; index > 0; index--) {
nextSequence = nextSequence.add(increment);
sequencesForName.addElement(nextSequence);
}
return sequencesForName;
}
}
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