DATACMNS-1251 - Added methods returning Instant to Revision.

Revision and RevisionMetadata now have methods returning Instant instead of LocalDateTime. The existing methods returning LocalDateTime are now deprecated.

Original pull request: #270.

src/main/java/org/springframework/data/history/AnnotationRevisionMetadata.java

@@ -16,7 +16,10 @@
 package org.springframework.data.history;
 
 import java.lang.annotation.Annotation;
+import java.time.Instant;
 import java.time.LocalDateTime;
+import java.time.ZoneOffset;
+import java.time.temporal.TemporalAccessor;
 import java.util.Optional;
 
 import org.springframework.data.util.AnnotationDetectionFieldCallback;
@@ -26,15 +29,17 @@ import org.springframework.util.ReflectionUtils;
 
 /**
  * A {@link RevisionMetadata} implementation that inspects the given object for fields with the configured annotations
- * and returns the field's values on calls to {@link #getRevisionDate()} and {@link #getRevisionNumber()}.
+ * and returns the field's values on calls to {@link #getRevisionDate()}, {@link #getRevisionInstant()} and
+ * {@link #getRevisionNumber()}.
  *
  * @author Oliver Gierke
+ * @author Jens Schauder
  */
 public class AnnotationRevisionMetadata<N extends Number & Comparable<N>> implements RevisionMetadata<N> {
 
 	private final Object entity;
 	private final Lazy<Optional<N>> revisionNumber;
-	private final Lazy<Optional<LocalDateTime>> revisionDate;
+	private final Lazy<Optional<TemporalAccessor>> revisionDate;
 
 	/**
 	 * Creates a new {@link AnnotationRevisionMetadata} inspecting the given entity for the given annotations. If no
@@ -68,8 +73,44 @@ public class AnnotationRevisionMetadata<N extends Number & Comparable<N>> implem
 	 * (non-Javadoc)
 	 * @see org.springframework.data.history.RevisionMetadata#getRevisionDate()
 	 */
+	@Deprecated
 	public Optional<LocalDateTime> getRevisionDate() {
-		return revisionDate.get();
+
+		return revisionDate.get().map(this::convertToLocalDateTime);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.history.RevisionMetadata#getRevisionDate()
+	 */
+	public Optional<Instant> getRevisionInstant() {
+		return revisionDate.get().map(this::convertToInstant);
+	}
+
+	private LocalDateTime convertToLocalDateTime(TemporalAccessor temporalAccessor) {
+
+		if (temporalAccessor instanceof LocalDateTime) {
+			return (LocalDateTime) temporalAccessor;
+		}
+
+		if (temporalAccessor instanceof Instant) {
+			return LocalDateTime.ofInstant((Instant) temporalAccessor, ZoneOffset.systemDefault());
+		}
+
+		throw new IllegalArgumentException(String.format("Can't convert %s to LocalDateTime", temporalAccessor));
+	}
+
+	private Instant convertToInstant(TemporalAccessor temporalAccessor) {
+
+		if (temporalAccessor instanceof Instant) {
+			return (Instant) temporalAccessor;
+		}
+
+		if (temporalAccessor instanceof LocalDateTime) {
+			return ((LocalDateTime) temporalAccessor).atZone(ZoneOffset.systemDefault()).toInstant();
+		}
+
+		throw new IllegalArgumentException(String.format("Can't convert %s to LocalDateTime", temporalAccessor));
 	}
 
 	/*

src/main/java/org/springframework/data/history/Revision.java

@@ -22,6 +22,7 @@ import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 import lombok.Value;
 
+import java.time.Instant;
 import java.time.LocalDateTime;
 import java.util.Optional;
 
@@ -33,6 +34,7 @@ import org.springframework.lang.Nullable;
  * @author Oliver Gierke
  * @author Philipp Huegelmeyer
  * @author Christoph Strobl
+ * @author Jens Schauder
  */
 @Value
 @RequiredArgsConstructor(access = AccessLevel.PRIVATE)
@@ -80,21 +82,43 @@ public final class Revision<N extends Number & Comparable<N>, T> implements Comp
 	/**
 	 * Returns the revision date of the revision.
 	 *
-	 * @return
+	 * @return Guaranteed to be not {@literal null}.
+	 * @deprecated Use {@link #getRevisionInstant()} instead.
 	 */
+	@Deprecated
 	public Optional<LocalDateTime> getRevisionDate() {
 		return metadata.getRevisionDate();
 	}
 
+	/**
+	 * Returns the timestamp of the revision.
+	 *
+	 * @return Guaranteed to be not {@literal null}.
+	 */
+	public Optional<Instant> getRevisionInstant() {
+		return metadata.getRevisionInstant();
+	}
+
 	/**
 	 * Returns the revision date of the revision, immediately failing on absence.
 	 *
 	 * @return the revision date.
+	 * @deprecated Use {@link #getRequiredRevisionInstant()} instead.
 	 */
+	@Deprecated
 	public LocalDateTime getRequiredRevisionDate() {
 		return metadata.getRequiredRevisionDate();
 	}
 
+	/**
+	 * Returns the timestamp of the revision, immediately failing on absence.
+	 *
+	 * @return the revision {@link Instant}. May be {@literal null}.
+	 */
+	public Instant getRequiredRevisionInstant() {
+		return metadata.getRequiredRevisionInstant();
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see java.lang.Comparable#compareTo(java.lang.Object)

src/main/java/org/springframework/data/history/RevisionMetadata.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.history;
 
+import java.time.Instant;
 import java.time.LocalDateTime;
 import java.util.Optional;
 
@@ -23,6 +24,7 @@ import java.util.Optional;
  *
  * @author Philipp Huegelmeyer
  * @author Oliver Gierke
+ * @author Jens Schauder
  */
 public interface RevisionMetadata<N extends Number & Comparable<N>> {
 
@@ -48,20 +50,43 @@ public interface RevisionMetadata<N extends Number & Comparable<N>> {
 	 * Returns the date of the revision.
 	 *
 	 * @return will never be {@literal null}.
+	 * @deprecated use {@link #getRevisionInstant()} instead.
 	 */
+	@Deprecated
 	Optional<LocalDateTime> getRevisionDate();
 
+	/**
+	 * Returns the timestamp of the revision.
+	 *
+	 * @return will never be {@literal null}.
+	 */
+	Optional<Instant> getRevisionInstant();
+
 	/**
 	 * Returns the revision date of the revision, immediately failing on absence.
 	 *
 	 * @return will never be {@literal null}.
-	 * @throw IllegalStateException if no revision date is available.
+	 * @throws IllegalStateException if no revision date is available.
+	 * @deprecated Use {@link #getRevisionInstant()} instead.
 	 */
+	@Deprecated
 	default LocalDateTime getRequiredRevisionDate() {
 		return getRevisionDate().orElseThrow(
 				() -> new IllegalStateException(String.format("No revision date found on %s!", (Object) getDelegate())));
 	}
 
+
+	/**
+	 * Returns the timestamp of the revision, immediately failing on absence.
+	 *
+	 * @return will never be {@literal null}.
+	 * @throws IllegalStateException if no revision date is available.
+	 */
+	default Instant getRequiredRevisionInstant() {
+		return getRevisionInstant().orElseThrow(
+				() -> new IllegalStateException(String.format("No revision date found on %s!", (Object) getDelegate())));
+	}
+
 	/**
 	 * Returns the underlying revision metadata which might provider more detailed implementation specific information.
 	 *