Move to enum representation of dialect values.

Author: schauder

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/jdbc/JdbcDataProperties.java

@@ -31,14 +31,13 @@ public class JdbcDataProperties {
 	/**
 	 * Dialect to use. By default, the dialect is determined by inspecting the database connection.
 	 */
-	private Class<? extends Dialect> dialect;
+	private JdbcDatabaseDialect dialect;
 
-	public Class<? extends Dialect> getDialect() {
+	public JdbcDatabaseDialect getDialect() {
 		return this.dialect;
 	}
 
-	public void setDialect(Class<? extends Dialect> dialect) {
+	public void setDialect(JdbcDatabaseDialect dialect) {
 		this.dialect = dialect;
 	}
-
 }

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/jdbc/JdbcDatabaseDialect.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2012-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.data.jdbc;
+
+import java.util.function.Supplier;
+
+import org.springframework.data.jdbc.core.dialect.JdbcDb2Dialect;
+import org.springframework.data.jdbc.core.dialect.JdbcMySqlDialect;
+import org.springframework.data.jdbc.core.dialect.JdbcPostgresDialect;
+import org.springframework.data.jdbc.core.dialect.JdbcSqlServerDialect;
+import org.springframework.data.relational.core.dialect.Db2Dialect;
+import org.springframework.data.relational.core.dialect.Dialect;
+import org.springframework.data.relational.core.dialect.H2Dialect;
+import org.springframework.data.relational.core.dialect.HsqlDbDialect;
+import org.springframework.data.relational.core.dialect.MariaDbDialect;
+import org.springframework.data.relational.core.dialect.OracleDialect;
+
+/**
+ * List of database dialects that can be configured in Boot for use with Spring Data JDBC.
+ *
+ * @author Jens Schauder
+ * @since 3.3
+ */
+public enum JdbcDatabaseDialect implements Supplier<Dialect> {
+
+	DB2 {
+		@Override
+		public Dialect get() {
+			return JdbcDb2Dialect.INSTANCE;
+		}
+	},
+	H2{
+		@Override
+		public Dialect get() {
+			return H2Dialect.INSTANCE;
+		}
+	},
+	HSQL{
+		@Override
+		public Dialect get() {
+			return HsqlDbDialect.INSTANCE;
+		}
+	},
+	MARIA{
+		@Override
+		public Dialect get() {
+			return MariaDbDialect.INSTANCE;
+		}
+	},
+	MYSQL{
+		@Override
+		public Dialect get() {
+			return JdbcMySqlDialect.INSTANCE;
+		}
+	},
+	ORACLE{
+		@Override
+		public Dialect get() {
+			return OracleDialect.INSTANCE;
+
+		}
+	},
+	POSTGRESQL{
+		@Override
+		public Dialect get() {
+			return JdbcPostgresDialect.INSTANCE;
+		}
+	},
+	SQL_SERVER{
+		@Override
+		public Dialect get() {
+			return JdbcSqlServerDialect.INSTANCE;
+		}
+	}
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/jdbc/JdbcRepositoriesAutoConfiguration.java

@@ -149,16 +149,9 @@ public DataAccessStrategy dataAccessStrategyBean(NamedParameterJdbcOperations op
 		@Bean
 		@ConditionalOnMissingBean
 		public Dialect jdbcDialect(NamedParameterJdbcOperations operations) {
-			if (this.properties.getDialect() != null
-			) {
-				Class<?> dialectType = this.properties.getDialect();
-				try {
-					return (Dialect)dialectType.getDeclaredConstructor().newInstance();
-				}
-				catch (InstantiationException | IllegalAccessException |
-					   InvocationTargetException | NoSuchMethodException e) {
-					throw new BeanCreationException("Couldn't create instance of type " + dialectType, e);
-				}
+			JdbcDatabaseDialect dialectEnum = this.properties.getDialect();
+			if (dialectEnum != null) {
+				return dialectEnum.get();
 			}
 			return super.jdbcDialect(operations);
 		}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/jdbc/JdbcRepositoriesAutoConfigurationTests.java

@@ -186,7 +186,7 @@ void allowsUserToDefineCustomDialect() {
 	@Test
 	void allowsConfigurationOfDialectByProperty() {
 		this.contextRunner.with(database())
-				.withPropertyValues("spring.data.jdbc.dialect:" + JdbcPostgresDialect.class.getName())
+				.withPropertyValues("spring.data.jdbc.dialect=postgresql" )
 				.withConfiguration(AutoConfigurations.of(JdbcTemplateAutoConfiguration.class,
 						DataSourceTransactionManagerAutoConfiguration.class))
 				.withUserConfiguration(TestConfiguration.class)