HHH-15781 make @GenericGenerator typesafe by adding type() member

this annotation is not deprecated, so we should at least make it typesafe

hibernate-core/src/main/java/org/hibernate/annotations/GenericGenerator.java

@@ -6,6 +6,8 @@
  */
 package org.hibernate.annotations;
 
+import org.hibernate.id.IdentifierGenerator;
+
 import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;
@@ -18,10 +20,16 @@ import static java.lang.annotation.RetentionPolicy.RUNTIME;
 
 /**
  * Defines a named identifier generator, an instance of the interface
- * {@link org.hibernate.id.IdentifierGenerator}. A named generator may be
- * associated with an entity class by:
+ * {@link org.hibernate.id.IdentifierGenerator}. This allows the use of
+ * custom identifier generation strategies beyond those provided by the
+ * four basic JPA-defined {@linkplain jakarta.persistence.GenerationType
+ * generation types}.
+ * <p>
+ * A named generator may be associated with an entity class by:
  * <ul>
- * <li>defining a named generator using this annotation, then
+ * <li>defining a named generator using this annotation, specifying an
+ *     implementation of {@code IdentifierGenerator} using {@link #type},
+ *     then
  * <li>annotating the identifier property of the entity with the JPA-defined
  *     {@link jakarta.persistence.GeneratedValue @GeneratedValue} annotation,
  *     and
@@ -29,10 +37,15 @@ import static java.lang.annotation.RetentionPolicy.RUNTIME;
  *     to specify the {@link #name()} of the generator defined using this
  *     annotation.
  * </ul>
+ * If neither {@link #type} not {@link #strategy} is specified, Hibernate asks
+ * {@linkplain org.hibernate.dialect.Dialect#getNativeIdentifierGeneratorStrategy
+ * the dialect} to decide an appropriate strategy. This is equivalent to using
+ * {@link jakarta.persistence.GenerationType#AUTO AUTO} in JPA.
+ * <p>
  * For example, if we define a generator using:
  * <pre>{@code
  * @GenericGenerator(name = "custom-generator",
- *                   strategy = "org.hibernate.eg.CustomStringGenerator")
+ *                   type = org.hibernate.eg.CustomStringGenerator.class)
  * }</pre>
  * Then we may make use of it by annotating an identifier field as follows:
  * <pre>{@code
@@ -61,13 +74,18 @@ public @interface GenericGenerator {
 	 */
 	String name();
 	/**
-	 * The type of identifier generator, either:
+	 * The type of identifier generator, a class implementing
+	 * {@link org.hibernate.id.IdentifierGenerator}.
+	 */
+	Class<? extends IdentifierGenerator> type() default IdentifierGenerator.class;
+	/**
+	 * The type of identifier generator, the name of either:
 	 * <ul>
- *     <li>the name of a built-in Hibernate id generator, or
+	 * <li>a built-in Hibernate id generator, or
 	 * <li>a custom class implementing {@link org.hibernate.id.IdentifierGenerator}.
 	 * </ul>
 	 */
-	String strategy();
+	String strategy() default "native";
 	/**
 	 * Parameters to be passed to {@link org.hibernate.id.IdentifierGenerator#configure}
 	 * when the identifier generator is instantiated.

hibernate-core/src/main/java/org/hibernate/cfg/AnnotationBinder.java

@@ -481,7 +481,10 @@ public final class AnnotationBinder {
 		else if ( generatorAnnotation instanceof GenericGenerator ) {
 			final GenericGenerator genericGenerator = (GenericGenerator) generatorAnnotation;
 			definitionBuilder.setName( genericGenerator.name() );
-			definitionBuilder.setStrategy( genericGenerator.strategy() );
+			final String strategy = genericGenerator.type().equals(IdentifierGenerator.class)
+					? genericGenerator.strategy()
+					: genericGenerator.type().getName();
+			definitionBuilder.setStrategy(strategy);
 			for ( Parameter parameter : genericGenerator.parameters() ) {
 				definitionBuilder.addParam( parameter.name(), parameter.value() );
 			}

hibernate-core/src/main/java/org/hibernate/id/factory/internal/StandardIdentifierGeneratorFactory.java

@@ -146,10 +146,9 @@ public class StandardIdentifierGeneratorFactory
 					AvailableSettings.IDENTIFIER_GENERATOR_STRATEGY_PROVIDER,
 					"supply a org.hibernate.id.factory.spi.GenerationTypeStrategyRegistration Java service"
 			);
-			final IdentifierGeneratorStrategyProvider idGeneratorStrategyProvider = serviceRegistry.getService( StrategySelector.class ).resolveStrategy(
-					IdentifierGeneratorStrategyProvider.class,
-					providerSetting
-			);
+			final IdentifierGeneratorStrategyProvider idGeneratorStrategyProvider =
+					serviceRegistry.getService( StrategySelector.class )
+							.resolveStrategy( IdentifierGeneratorStrategyProvider.class, providerSetting );
 			for ( Map.Entry<String,Class<?>> entry : idGeneratorStrategyProvider.getStrategies().entrySet() ) {
 				register( entry.getKey(), (Class) entry.getValue() );
 			}
@@ -238,20 +237,21 @@ public class StandardIdentifierGeneratorFactory
 		if ( "hilo".equals( strategy ) ) {
 			throw new UnsupportedOperationException( "Support for 'hilo' generator has been removed" );
 		}
-		String resolvedStrategy = "native".equals( strategy )
+		final String resolvedStrategy = "native".equals( strategy )
 				? getDialect().getNativeIdentifierGeneratorStrategy()
 				: strategy;
 
-		Class generatorClass = legacyGeneratorClassNameMap.get( resolvedStrategy );
-		try {
+		Class<? extends IdentifierGenerator> generatorClass = legacyGeneratorClassNameMap.get( resolvedStrategy );
 		if ( generatorClass == null ) {
-				final ClassLoaderService cls = serviceRegistry.getService( ClassLoaderService.class );
-				generatorClass = cls.classForName( resolvedStrategy );
-			}
+			try {
+				return serviceRegistry.getService( ClassLoaderService.class ).classForName( resolvedStrategy );
 			}
 			catch ( ClassLoadingException e ) {
 				throw new MappingException( String.format( "Could not interpret id generator strategy [%s]", strategy ) );
 			}
+		}
+		else {
 			return generatorClass;
 		}
+	}
 }

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/id/entities/Bunny.java

@@ -14,7 +14,6 @@ import jakarta.persistence.CascadeType;
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.OneToMany;
 
@@ -27,11 +26,10 @@ import org.hibernate.annotations.GenericGenerator;
  * @author Andrew C. Oliver andyspam@osintegrators.com
  */
 @Entity
-@SuppressWarnings("serial")
 public class Bunny implements Serializable {
 	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY, generator = "java5_uuid")
-	@GenericGenerator(name = "java5_uuid", strategy = "org.hibernate.orm.test.annotations.id.UUIDGenerator")
+	@GeneratedValue(generator = "java5_uuid")
+	@GenericGenerator(name = "java5_uuid", type = org.hibernate.orm.test.annotations.id.UUIDGenerator.class)
 	@Column(name = "id", precision = 128, scale = 0)
 	private BigDecimal id;
 

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/id/entities/PointyTooth.java

@@ -12,7 +12,6 @@ import java.math.BigDecimal;
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
@@ -27,11 +26,10 @@ import org.hibernate.annotations.GenericGenerator;
  * @author Andrew C. Oliver andyspam@osintegrators.com
  */
 @Entity
-@SuppressWarnings("serial")
 public class PointyTooth implements Serializable {
 	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY, generator = "java5_uuid")
-	@GenericGenerator(name = "java5_uuid", strategy = "org.hibernate.orm.test.annotations.id.UUIDGenerator")
+	@GeneratedValue(generator = "java5_uuid")
+	@GenericGenerator(name = "java5_uuid", type = org.hibernate.orm.test.annotations.id.UUIDGenerator.class)
 	@Column(name = "id", precision = 128, scale = 0)
 	private BigDecimal id;
 

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/id/entities/TwinkleToes.java

@@ -12,7 +12,6 @@ import java.math.BigDecimal;
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
@@ -27,11 +26,10 @@ import org.hibernate.annotations.GenericGenerator;
  * @author Andrew C. Oliver andyspam@osintegrators.com
  */
 @Entity
-@SuppressWarnings("serial")
 public class TwinkleToes implements Serializable {
 	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY, generator = "java5_uuid")
-	@GenericGenerator(name = "java5_uuid", strategy = "org.hibernate.orm.test.annotations.id.UUIDGenerator")
+	@GeneratedValue(generator = "java5_uuid")
+	@GenericGenerator(name = "java5_uuid", type = org.hibernate.orm.test.annotations.id.UUIDGenerator.class)
 	@Column(name = "id", precision = 128, scale = 0)
 	private BigDecimal id;
 

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/id/sequences/entities/Bunny.java

@@ -14,7 +14,6 @@ import jakarta.persistence.CascadeType;
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.OneToMany;
 
@@ -27,11 +26,10 @@ import org.hibernate.annotations.GenericGenerator;
  * @author Andrew C. Oliver andyspam@osintegrators.com
  */
 @Entity
-@SuppressWarnings("serial")
 public class Bunny implements Serializable {
 	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY, generator = "java5_uuid")
-	@GenericGenerator(name = "java5_uuid", strategy = "org.hibernate.orm.test.annotations.id.UUIDGenerator")
+	@GeneratedValue(generator = "java5_uuid")
+	@GenericGenerator(name = "java5_uuid", type = org.hibernate.orm.test.annotations.id.UUIDGenerator.class)
 	@Column(name = "id", precision = 128, scale = 0)
 	private BigDecimal id;
 

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/id/sequences/entities/PointyTooth.java

@@ -12,7 +12,6 @@ import java.math.BigDecimal;
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
@@ -27,11 +26,10 @@ import org.hibernate.annotations.GenericGenerator;
  * @author Andrew C. Oliver andyspam@osintegrators.com
  */
 @Entity
-@SuppressWarnings("serial")
 public class PointyTooth implements Serializable {
 	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY, generator = "java5_uuid")
-	@GenericGenerator(name = "java5_uuid", strategy = "org.hibernate.orm.test.annotations.id.UUIDGenerator")
+	@GeneratedValue(generator = "java5_uuid")
+	@GenericGenerator(name = "java5_uuid", type = org.hibernate.orm.test.annotations.id.UUIDGenerator.class)
 	@Column(name = "id", precision = 128, scale = 0)
 	private BigDecimal id;
 

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/id/sequences/entities/TwinkleToes.java

@@ -12,7 +12,6 @@ import java.math.BigDecimal;
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
@@ -27,11 +26,10 @@ import org.hibernate.annotations.GenericGenerator;
  * @author Andrew C. Oliver andyspam@osintegrators.com
  */
 @Entity
-@SuppressWarnings("serial")
 public class TwinkleToes implements Serializable {
 	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY, generator = "java5_uuid")
-	@GenericGenerator(name = "java5_uuid", strategy = "org.hibernate.orm.test.annotations.id.UUIDGenerator")
+	@GeneratedValue(generator = "java5_uuid")
+	@GenericGenerator(name = "java5_uuid", type = org.hibernate.orm.test.annotations.id.UUIDGenerator.class)
 	@Column(name = "id", precision = 128, scale = 0)
 	private BigDecimal id;