Improve database initializers

This commit improves database initializers for Spring Batch and Spring
Session by introducing `AbstractDatabaseInitializer` which eliminates
duplicated logic in existing initializers. Additionally, database
platform resolution now relies on `DatabaseDriver`.

See gh-6543

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/AbstractDatabaseInitializer.java

+/*
+ * Copyright 2012-2016 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
+ *
+ *      http://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;
+
+import javax.annotation.PostConstruct;
+import javax.sql.DataSource;
+
+import org.springframework.boot.jdbc.DatabaseDriver;
+import org.springframework.core.io.ResourceLoader;
+import org.springframework.jdbc.datasource.init.DatabasePopulatorUtils;
+import org.springframework.jdbc.datasource.init.ResourceDatabasePopulator;
+import org.springframework.jdbc.support.JdbcUtils;
+import org.springframework.jdbc.support.MetaDataAccessException;
+import org.springframework.util.Assert;
+
+/**
+ * Abstract base class for database schema initializers.
+ *
+ * @author Vedran Pavic
+ * @since 1.5.0
+ */
+public abstract class AbstractDatabaseInitializer {
+
+	private static final String PLATFORM_PLACEHOLDER = "@@platform@@";
+
+	private DataSource dataSource;
+
+	private ResourceLoader resourceLoader;
+
+	public AbstractDatabaseInitializer(DataSource dataSource, ResourceLoader resourceLoader) {
+		Assert.notNull(dataSource, "DataSource must not be null");
+		Assert.notNull(resourceLoader, "ResourceLoader must not be null");
+		this.dataSource = dataSource;
+		this.resourceLoader = resourceLoader;
+	}
+
+	@PostConstruct
+	protected void initialize() {
+		if (isEnabled()) {
+			ResourceDatabasePopulator populator = new ResourceDatabasePopulator();
+			String schemaLocation = getSchemaLocation();
+			if (schemaLocation.contains(PLATFORM_PLACEHOLDER)) {
+				String platform = customizeDatabaseName(getDatabaseName());
+				schemaLocation = schemaLocation.replace(PLATFORM_PLACEHOLDER, platform);
+			}
+			populator.addScript(this.resourceLoader.getResource(schemaLocation));
+			populator.setContinueOnError(true);
+			DatabasePopulatorUtils.execute(populator, this.dataSource);
+		}
+	}
+
+	protected abstract boolean isEnabled();
+
+	protected abstract String getSchemaLocation();
+
+	protected String customizeDatabaseName(String databaseName) {
+		return databaseName;
+	}
+
+	private String getDatabaseName() {
+		try {
+			String databaseProductName = JdbcUtils.extractDatabaseMetaData(
+					this.dataSource, "getDatabaseProductName").toString();
+			databaseProductName = JdbcUtils.commonDatabaseName(databaseProductName);
+			DatabaseDriver databaseDriver = DatabaseDriver.fromProductName(
+					databaseProductName);
+			if (databaseDriver == DatabaseDriver.UNKNOWN) {
+				throw new IllegalStateException("Unable to detect database type");
+			}
+			return databaseDriver.toString().toLowerCase();
+		}
+		catch (MetaDataAccessException ex) {
+			throw new IllegalStateException("Unable to detect database type", ex);
+		}
+	}
+
+}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/batch/BatchAutoConfiguration.java

@@ -40,6 +40,7 @@ import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfigurat
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.io.ResourceLoader;
 import org.springframework.jdbc.core.JdbcOperations;
 import org.springframework.util.StringUtils;
 
@@ -77,8 +78,9 @@ public class BatchAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	@ConditionalOnBean(DataSource.class)
-	public BatchDatabaseInitializer batchDatabaseInitializer() {
-		return new BatchDatabaseInitializer();
+	public BatchDatabaseInitializer batchDatabaseInitializer(DataSource dataSource,
+			ResourceLoader resourceLoader) {
+		return new BatchDatabaseInitializer(dataSource, resourceLoader, this.properties);
 	}
 
 	@Bean

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/batch/BatchDatabaseInitializer.java

@@ -16,63 +16,45 @@
 
 package org.springframework.boot.autoconfigure.batch;
 
-import javax.annotation.PostConstruct;
 import javax.sql.DataSource;
 
-import org.springframework.batch.support.DatabaseType;
-import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.AbstractDatabaseInitializer;
 import org.springframework.core.io.ResourceLoader;
-import org.springframework.jdbc.datasource.init.DatabasePopulatorUtils;
-import org.springframework.jdbc.datasource.init.ResourceDatabasePopulator;
-import org.springframework.jdbc.support.MetaDataAccessException;
-import org.springframework.stereotype.Component;
+import org.springframework.util.Assert;
 
 /**
  * Initialize the Spring Batch schema (ignoring errors, so should be idempotent).
  *
  * @author Dave Syer
+ * @author Vedran Pavic
  */
-@Component
-public class BatchDatabaseInitializer {
+public class BatchDatabaseInitializer extends AbstractDatabaseInitializer {
 
-	@Autowired
 	private BatchProperties properties;
 
-	@Autowired
-	private DataSource dataSource;
+	public BatchDatabaseInitializer(DataSource dataSource,
+			ResourceLoader resourceLoader, BatchProperties properties) {
+		super(dataSource, resourceLoader);
+		Assert.notNull(properties, "BatchProperties must not be null");
+		this.properties = properties;
+	}
 
-	@Autowired
-	private ResourceLoader resourceLoader;
+	@Override
+	protected boolean isEnabled() {
+		return this.properties.getInitializer().isEnabled();
+	}
 
-	@PostConstruct
-	protected void initialize() {
-		if (this.properties.getInitializer().isEnabled()) {
-			String platform = getDatabaseType();
-			if ("hsql".equals(platform)) {
-				platform = "hsqldb";
-			}
-			if ("postgres".equals(platform)) {
-				platform = "postgresql";
-			}
-			if ("oracle".equals(platform)) {
-				platform = "oracle10g";
-			}
-			ResourceDatabasePopulator populator = new ResourceDatabasePopulator();
-			String schemaLocation = this.properties.getSchema();
-			schemaLocation = schemaLocation.replace("@@platform@@", platform);
-			populator.addScript(this.resourceLoader.getResource(schemaLocation));
-			populator.setContinueOnError(true);
-			DatabasePopulatorUtils.execute(populator, this.dataSource);
-		}
+	@Override
+	protected String getSchemaLocation() {
+		return this.properties.getSchema();
 	}
 
-	private String getDatabaseType() {
-		try {
-			return DatabaseType.fromMetaData(this.dataSource).toString().toLowerCase();
-		}
-		catch (MetaDataAccessException ex) {
-			throw new IllegalStateException("Unable to detect database type", ex);
+	@Override
+	protected String customizeDatabaseName(String databaseName) {
+		if ("oracle".equals(databaseName)) {
+			return "oracle10g";
 		}
+		return databaseName;
 	}
 
 }

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/session/JdbcSessionConfiguration.java

@@ -47,9 +47,9 @@ class JdbcSessionConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	public JdbcSessionDatabaseInitializer jdbcSessionDatabaseInitializer(
-			SessionProperties properties, DataSource dataSource,
-			ResourceLoader resourceLoader) {
-		return new JdbcSessionDatabaseInitializer(properties, dataSource, resourceLoader);
+			DataSource dataSource, ResourceLoader resourceLoader,
+			SessionProperties properties) {
+		return new JdbcSessionDatabaseInitializer(dataSource, resourceLoader, properties);
 	}
 
 	@Configuration

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/session/JdbcSessionDatabaseInitializer.java

@@ -16,18 +16,10 @@
 
 package org.springframework.boot.autoconfigure.session;
 
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
-
-import javax.annotation.PostConstruct;
 import javax.sql.DataSource;
 
+import org.springframework.boot.autoconfigure.AbstractDatabaseInitializer;
 import org.springframework.core.io.ResourceLoader;
-import org.springframework.jdbc.datasource.init.DatabasePopulatorUtils;
-import org.springframework.jdbc.datasource.init.ResourceDatabasePopulator;
-import org.springframework.jdbc.support.JdbcUtils;
-import org.springframework.jdbc.support.MetaDataAccessException;
 import org.springframework.util.Assert;
 
 /**
@@ -36,64 +28,25 @@ import org.springframework.util.Assert;
  * @author Vedran Pavic
  * @since 1.4.0
  */
-public class JdbcSessionDatabaseInitializer {
-
-	private static Map<String, String> ALIASES;
-
-	static {
-		Map<String, String> aliases = new HashMap<String, String>();
-		aliases.put("apache derby", "derby");
-		aliases.put("hsql database engine", "hsqldb");
-		aliases.put("microsoft sql server", "sqlserver");
-		ALIASES = Collections.unmodifiableMap(aliases);
-	}
+public class JdbcSessionDatabaseInitializer extends AbstractDatabaseInitializer {
 
-	private SessionProperties properties;
+	private SessionProperties.Jdbc properties;
 
-	private DataSource dataSource;
-
-	private ResourceLoader resourceLoader;
-
-	public JdbcSessionDatabaseInitializer(SessionProperties properties,
-			DataSource dataSource, ResourceLoader resourceLoader) {
+	public JdbcSessionDatabaseInitializer(DataSource dataSource,
+			ResourceLoader resourceLoader, SessionProperties properties) {
+		super(dataSource, resourceLoader);
 		Assert.notNull(properties, "SessionProperties must not be null");
-		Assert.notNull(dataSource, "DataSource must not be null");
-		Assert.notNull(resourceLoader, "ResourceLoader must not be null");
-		this.properties = properties;
-		this.dataSource = dataSource;
-		this.resourceLoader = resourceLoader;
-	}
-
-	@PostConstruct
-	protected void initialize() {
-		if (this.properties.getJdbc().getInitializer().isEnabled()) {
-			ResourceDatabasePopulator populator = new ResourceDatabasePopulator();
-			String schemaLocation = this.properties.getJdbc().getSchema();
-			schemaLocation = schemaLocation.replace("@@platform@@", getPlatform());
-			populator.addScript(this.resourceLoader.getResource(schemaLocation));
-			populator.setContinueOnError(true);
-			DatabasePopulatorUtils.execute(populator, this.dataSource);
-		}
+		this.properties = properties.getJdbc();
 	}
 
-	private String getPlatform() {
-		String databaseName = getDatabaseName();
-		if (ALIASES.containsKey(databaseName)) {
-			return ALIASES.get(databaseName);
-		}
-		return databaseName;
+	@Override
+	protected boolean isEnabled() {
+		return this.properties.getInitializer().isEnabled();
 	}
 
-	private String getDatabaseName() {
-		try {
-			String databaseProductName = JdbcUtils
-					.extractDatabaseMetaData(this.dataSource, "getDatabaseProductName")
-					.toString();
-			return JdbcUtils.commonDatabaseName(databaseProductName).toLowerCase();
-		}
-		catch (MetaDataAccessException ex) {
-			throw new IllegalStateException("Unable to detect database type", ex);
-		}
+	@Override
+	protected String getSchemaLocation() {
+		return this.properties.getSchema();
 	}
 
 }